Search results

Title: Spatiotemporal Variability and Prediction of Rainfall over the Eastern Caribbean.
Creator: Pologne, Lawrence, Cai, Ming, Krishnamurti, T. N., Hart, Robert, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Recent, recurrent, and extreme weather events have been a cause for concern over the Eastern Caribbean (EC). Given the dependence on rainfall of agriculture, the main stay of the fragile economies throughout the region, accurate and timely forecasts of seasonal rainfall need to be issued to facilitate decision making in Water Resource Management. Understanding the causes of climate variability can lead to the development of more robust models for climate prediction. So as a diagnostic...
Show moreRecent, recurrent, and extreme weather events have been a cause for concern over the Eastern Caribbean (EC). Given the dependence on rainfall of agriculture, the main stay of the fragile economies throughout the region, accurate and timely forecasts of seasonal rainfall need to be issued to facilitate decision making in Water Resource Management. Understanding the causes of climate variability can lead to the development of more robust models for climate prediction. So as a diagnostic approach, different techniques are employed. Empirical Orthogonal Function (EOF) analysis is performed in order to isolate the different modes of rainfall variability as well as investigating their amplitudinal modulations. The evolution of external forcing mechanisms that impact on precipitation extremes is also investigated with the use of composites. Based on the strength of the relationship between Sea Surface Temperature Anomalies (SSTA) and EC rainfall, a statistical model is subsequently developed using multivariate Canonical Correlation Analysis (CCA) to predict rainfall over the region on seasonal time scales. The CCA model demonstrated useful skill in predicting seasonal rainfall over the EC up to six months lead. The highest average predictive skill is realized for the June-July-August (JJA) season at one-month lead, while the lowest average skill is realized for the March-April-May (MAM) season at five months lead. The December-January-February (DJF) season maintained steady skill throughout six months lead. Below normal conditions are forecasted by the CCA model for the 2004/2005 dry season (DJF/2004-05, MAM/2005). This outlook is in part, verified from seasonal rainfall totals at two stations within the EC. The outlook for the coming rainy season is for above normal conditions.
Show less
Date Issued: 2005
Identifier: FSU_migr_etd-0510
Format: Thesis

Title: Assessment of Groundwater Discharge to Lake Barco via Radon Tracing.
Creator: Stringer, Christina Elaine, Burnett, William C., Chanton, Jeffrey P., Sturges, Wilton, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Groundwater-surface water interactions in lakes have been gaining attention in recent years as scientists have recognized the potential significance that groundwater has as a source of nutrients and contaminants to aquatic ecosystems. Such interactions need to be understood in order for us to protect important ecosystems and quantify nutrient loading into lakes. This project set out to test the idea that good estimates could be made of groundwater inputs into Florida lakes using a simple...
Show moreGroundwater-surface water interactions in lakes have been gaining attention in recent years as scientists have recognized the potential significance that groundwater has as a source of nutrients and contaminants to aquatic ecosystems. Such interactions need to be understood in order for us to protect important ecosystems and quantify nutrient loading into lakes. This project set out to test the idea that good estimates could be made of groundwater inputs into Florida lakes using a simple geochemical tracer technique. We hypothesize that a relatively small number of measurements would be sufficient to provide a reasonably good (a factor of 2) estimate of groundwater discharge. Naturally occurring 222Rn makes an ideal tracer because it exists in enriched concentrations in groundwater relative to surface water. We used Lake Barco, a small seepage lake in the Katherine Ordway Preserve, for a detailed pilot study in order to test this hypothesis. The preserve is located about 34 km east of Gainesville, Florida and makes an excellent research site because it is maintained in a pristine state as it is closed off to public access. Two intensive samplings were completed, one in the "dry" season (March 2002) and one in the "wet" season (August 2003). In addition, periodic sampling trips were made to the lake every few weeks to evaluate the spatial and temporal patterns of radon distribution. A 222Rn mass balance was constructed for the lake to evaluate radon fluxes. Once the 222Rn fluxes were determined, groundwater inputs were estimated by dividing these fluxes by the concentration of radon in the water seeping into the lake. The radon concentration is estimated by sediment equilibration experiments using grab samples of sediment and radon activity measurements from monitor wells. We also constructed a traditional hydrologic water budget for Lake Barco. All hydrological variables were either measured or estimated and substituted into a water balance equation, which was then solved for the net groundwater flow term. These estimates were then compared to those from the 222Rn model. Our 222Rn measurements show little discernible spatial variation of radon inventories in the lake on any given day of sampling. Inventories measured at five different stations during the two different intensive sampling trips were all within ±13% of the mean value for each sampling. This amount of variation is considered insignificant, as the estimated analytical variation for the radon measurements is ±10%. We also found that we can estimate the lake inventory at any one station by collecting triplicate samples approximately one meter over the bottom at a single central sampling station. However, our results did display significant temporal variability, responding to rainfall trends that can influence the recharge rates. So, in a lake the size of Lake Barco (12 ha), reasonable groundwater discharge estimates at any given time can be made by triplicate analysis of radon in near-bottom waters and collection and processing of a few sediment samples. The estimations of groundwater discharge to the lake over the period of our study were, on average, 13,000 m3/month and 18,000 m3/month for the radon model and hydrologic budget, respectively. The water balance based estimate might be somewhat low due to differences in hydrogeologic movement under such dry conditions or the large error associated with budget estimations. Considering the large uncertainties in estimating groundwater flow via a hydrologic budget, agreement within a factor of two is considered satisfactory.
Show less
Date Issued: 2004
Identifier: FSU_migr_etd-0395
Format: Thesis

Title: Metabolic Pathways in Natural Systems: A Tracer Study of Carbon Isotopes.
Creator: Prater, James L., Chanton, Jeffrey P., Wang, Yang, Kostka, Joel E., Mortazavi, Behzad, Burnett, William C., Winchester, John W., Department of Earth, Ocean and Atmospheric...
Show morePrater, James L., Chanton, Jeffrey P., Wang, Yang, Kostka, Joel E., Mortazavi, Behzad, Burnett, William C., Winchester, John W., Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Show less
Abstract/Description: The δ13C value of foliage respiration has been considered a constant in the past and modeling efforts have assumed that the δ13C value of foliage respiration is constant and is directly related to substrate without any fractionation. Consecutive δ13C measurements of foliage dark-respired CO2 (δ13Cr) for slash pine trees (Pinus elliottii) over several diel cycles were used to test the hypothesis that significant variation in δ13Cr would be observed. δ13Cr values collected in daylight from all...
Show moreThe δ13C value of foliage respiration has been considered a constant in the past and modeling efforts have assumed that the δ13C value of foliage respiration is constant and is directly related to substrate without any fractionation. Consecutive δ13C measurements of foliage dark-respired CO2 (δ13Cr) for slash pine trees (Pinus elliottii) over several diel cycles were used to test the hypothesis that significant variation in δ13Cr would be observed. δ13Cr values collected in daylight from all time series showed mid- day 13C enrichment (5 – 10‰) relative to bulk biomass, but values become more 13C depleted following shading and at night and approach bulk-biomass δ13C values by dawn. Assimilation model results suggest that respiration during daylight has the potential to significantly affect ∆13C by as much as 1.6‰, but night dark respiration has little impact on 24-hour integrated ∆13C (0.1‰). We also sampled methane and CO2 from collapse scar bogs (transient permafrost degradation features in permafrost peatlands) to test the hypotheses that microbial respiration and methane production are stimulated by permafrost degradation and collapse and that the fen-like vegetation (i.e. Carex andxi Eriophorum) found in collapse scar bogs near the collapsing edge stimulates acetate fermentation. Our results show that collapse scar bogs have an evolution of spatial variation in methanogenic pathways that is related to surface vegetation cover type. We also demonstrate that changes in stable-isotope fractionation caused by shifts from acetate fermentation and CO2 reduction occur over long time scales (> annual) and are dependent on changes in wetland morphology and surface vegetation cover. We also used radiocarbon as a tracer to test the hypothesis that melting permafrost surrounding the collapse scar bog provides nutrients to the bog-moat location, stimulating the production of radiocarbon-depleted methane. Our results show that the radiocarbon content of methane and DIC at these sites is highly variable and may depend on groundwater input, surface vegetation, and morphological factors associated with the melting permafrost plateau. We conclude that the younger, more labile, carbon stimulating acetate fermentation at one of the sites is supplied by the fen-like surface vegetation, while the older, more recalcitrant, carbon stimulating CO2 reduction at the other site may be supplied by melting permafrost plateau..
Show less
Date Issued: 2005
Identifier: FSU_migr_etd-0429
Format: Thesis

Title: Morphological Barrier Island Changes and Recovery of Dunes after Hurricane Dennis, St. George Island, Florida.
Creator: Priestas, Anthony Michael, Fagherazzi, Sergio, Stallins, J. Anthony, Kish, Stephen, Georgen, Jennifer, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: A robust dune system is one of the principal factors in the protection of recreational and residential property within barrier islands. Storm surge from significantly large storm events may remove some or all of the dunes during overwash processes and deposit sediment as washover fans or terraces in the back-barrier. During the summer of 2005, Hurricane Dennis greatly overwashed much of the northwest barrier island chain along the Florida panhandle. The post-storm recovery of dunes and...
Show moreA robust dune system is one of the principal factors in the protection of recreational and residential property within barrier islands. Storm surge from significantly large storm events may remove some or all of the dunes during overwash processes and deposit sediment as washover fans or terraces in the back-barrier. During the summer of 2005, Hurricane Dennis greatly overwashed much of the northwest barrier island chain along the Florida panhandle. The post-storm recovery of dunes and morphological changes occurring after Hurricane Dennis within St. George Island State Park is investigated, in addition to the application of numerical methods as a supplemental tool in determining the post-storm "recovery state" of the barrier and envision morphologic trends. Dune recovery rates are estimated by calculating sediment volume changes of profiles through time. One-dimensional, spatial-series Fourier analysis of individual profiles are used to quantify the recovery and morphologic nature of secondary dunes. Two-dimensional Fourier analysis of elevation data were attempted to be used as a tool to discriminate geomorphic trends in the barrier. Digital elevation models are used to describe post-storm morphologic changes, and the future recovery state of the barrier may be supplemented by analyzing the distributions of curvature and gradients calculated numerically from LIDAR data. Results show that secondary dunes recovered at an average rate of ~3-4 cm per month, and sediment volume changes across transects varied between -1.5 m3/m to1.2 m3/m depending on the presence of vegetation, storm-debris pavement, and proximity to washover deposits. Despite some transects having a net sediment volume loss, all dunes in the presence of vegetation had increased in height. Vegetation did not propagate where storm-debris pavement existed during the one-year duration of the study. The presence of vegetation inhibited dune migration thus favoring dune growth or decreasing the effect of erosion from strong wind events. Fourier analysis of profiles captured changes in dune height at specific wavelengths. The highest energies from the spectra were usually at 30 to 40 meter wavelengths for each profile in time, which reflects the immobility of the dunes and may also reflect the controls of vegetation on dune spacing. The results of two-dimensional Fourier analysis on terrain data were difficult to interpret, but may prove a potential use in terrain analysis. Overwash was prevalent throughout the barrier. For the studied area, St. George Island had experienced inundation overwash with an estimated 100,000 ft3/ft net loss of sediment following the hurricane. Nearly the entire foredune complex was removed, save a few remnants. Storm surge had likely penetrated first in areas where foredunes were either low or discontinuous; in these areas, beach widening was less prevalent. In contrast, the beach widening (~30ft) occurred in areas where the foredunes were higher and more continuous.
Show less
Date Issued: 2009
Identifier: FSU_migr_etd-0458
Format: Thesis

Title: Ecology of Phytoplankton, Acartia Tonsa, and Microzooplankton in Apalachicola Bay, Florida.
Creator: Putland, Jennifer Nancy, Iverson, Richard, Wise, Sherwood, Marcus, Nancy, Kostka, Joel, Mortazavi, Behzad, Department of Earth, Ocean and Atmospheric Sciences, Florida State...
Show morePutland, Jennifer Nancy, Iverson, Richard, Wise, Sherwood, Marcus, Nancy, Kostka, Joel, Mortazavi, Behzad, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Show less
Abstract/Description: Apalachicola Bay is a productive estuary located in the northern Gulf of Mexico. The high productivity is, in part, the result of the Apalachicola River delivering freshwater and nutrients to the Bay. Nutrient input supports high levels of phytoplankton productivity, which supports the Bay's secondary productivity. Diversion of water from headwaters of the Apalachicola River during summer has been proposed to satisfy upstream freshwater requirements for recreation and agriculture. Knowledge...
Show moreApalachicola Bay is a productive estuary located in the northern Gulf of Mexico. The high productivity is, in part, the result of the Apalachicola River delivering freshwater and nutrients to the Bay. Nutrient input supports high levels of phytoplankton productivity, which supports the Bay's secondary productivity. Diversion of water from headwaters of the Apalachicola River during summer has been proposed to satisfy upstream freshwater requirements for recreation and agriculture. Knowledge of the ecology of phytoplankton and zooplankton in the Bay is needed to help predict the effects of upstream water diversion on Apalachicola Bay. In this study, the temporal and spatial distribution of phytoplankton size composition, growth, biomass, productivity, microzooplankton bacterivory, herbivory, production, and Acartia tonsa herbivory, carnivory, egg production rate, and egg production efficiency were determined in Apalachicola Bay during 2003 and 2004. Phytoplankton growth, biomass, productivity, total ingestion rates and production rates of microzooplankton, and total ingestion rates and egg production rates of Acartia tonsa peaked during summer within lower salinity (psu) waters. Microzooplankton ingested, on average, ten times more phytoplankton productivity than A. tonsa. Compared to the 24 year average river discharge, river discharge into Apalachicola Bay was above average during 2003 and below average during 2004. On average, 100% and about 50% of the surface salinity of the Bay was 2004, respectively. Nutrient concentrations, at a specific salinity, were higher during 2003 than during 2004. Phytoplankton growth and productivity, as well as total ingestion rates and production rates of microzooplankton, at a specific salinity, were higher during summer 2003 than during summer 2004. It is expected that withdrawal of freshwater from the Apalachicola River during summer will lead to reduced higher trophic level production in Apalachicola Bay because of (1) reduced productivity of phyto- and microzooplankton at a specific salinity and (2) increased areal extent of higher salinity water (>20 psu) where phytoplankton growth, biomass, and productivity and zooplankton productivity is low. Implications of these results are also discussed with respect to our understanding of estuarine planktonic food web structure.20 psu) where phytoplankton growth, biomass, and productivity and zooplankton productivity is low. Implications of these results are also discussed with respect to our understanding of estuarine planktonic food web structure.
Show less
Date Issued: 2005
Identifier: FSU_migr_etd-0505
Format: Thesis

Title: Multiple Isotopic Tracers for Study of Coastal Hydrological Processes.
Creator: Dulaiova, Henrieta, Burnett, William C., Donoghue, Joseph F., Chanton, Jeffrey P., Landing, William M., Moore, Willard S., Kostka, Joel E., Department of Earth, Ocean and...
Show moreDulaiova, Henrieta, Burnett, William C., Donoghue, Joseph F., Chanton, Jeffrey P., Landing, William M., Moore, Willard S., Kostka, Joel E., Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Show less
Abstract/Description: This study focused on the combined use of radon and radium isotopes as tracers of near-shore geophysical processes including submarine groundwater discharge (SGD), water exchange rates, and atmospheric evasion. Methods were developed for easier measurement of long-lived radium isotopes in natural waters and for continuous radon surveying over larger areas in the coastal zone. These tracer techniques were used to study the mentioned processes at study sites in Shelter Island Sound (New York),...
Show moreThis study focused on the combined use of radon and radium isotopes as tracers of near-shore geophysical processes including submarine groundwater discharge (SGD), water exchange rates, and atmospheric evasion. Methods were developed for easier measurement of long-lived radium isotopes in natural waters and for continuous radon surveying over larger areas in the coastal zone. These tracer techniques were used to study the mentioned processes at study sites in Shelter Island Sound (New York), the Gulf of Thailand, and Apalachicola Bay, Florida. Groundwater fluxes calculated for Shelter Island using isotopic techniques produced results consistent with those measured directly via seepage meters. Groundwater discharge in the Chao Phraya Estuary (Thailand) was shown to be in the range of 2 to 20 m3/s, small compared to river discharge but much higher than seepage rates measured in nearby locations. An experimental assessment of Rn-222 evasion to the atmosphere was performed using radon and Ra-224 profiles in the Chao-Phraya Estuary in Thailand. The different trends in radium and radon isotopes measured in the estuary provided an estimate of atmospheric exchange that agreed with a theoretical approach. Short-lived radium isotopes were applied in a seasonal study of water residence time in Apalachicola Bay, Florida. The water transport within different sectors of the bay was evaluated as a result of advective (estuarine) and dispersive physical mixing. The distribution of the radium isotope ratios was used to determine apparent radium ages of the water within the bay. The results clearly showed how the water-residence time in the bay changes seasonally and that the winds and tides influence the water circulation in the bay. The radium tracer approach gave turnover times of 6 to 12 days in Apalachicola Bay during the studied periods.
Show less
Date Issued: 2005
Identifier: FSU_migr_etd-0643
Format: Thesis

Title: Interannual Flow off Southern California and Its Influence on Water Properties and Marine Life.
Creator: Dottori, Marcelo, Clarke, Allan J., Tam, Christopher, Nof, Doron, Weatherly, Georges, Dittmar, Thorsten, Department of Earth, Ocean and Atmospheric Sciences, Florida State...
Show moreDottori, Marcelo, Clarke, Allan J., Tam, Christopher, Nof, Doron, Weatherly, Georges, Dittmar, Thorsten, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Show less
Abstract/Description: Lagged correlation of dynamic height from the gappy California Cooperative Oceanic Fisheries Investigation (CalCOFI) with monthly San Diego sea level for the period 1949-2001 shows that the dynamic height propagates westward at 4.10 cm/s, about double the speed of the large-scale low frequency Rossby wave (2.2 cm/s). TOPEX/Poseidon/Jason1 along-track sea level height estimates since January 1993, filtered interannually, propagate westward at 4.3 cm/s, verifying that observed westward...
Show moreLagged correlation of dynamic height from the gappy California Cooperative Oceanic Fisheries Investigation (CalCOFI) with monthly San Diego sea level for the period 1949-2001 shows that the dynamic height propagates westward at 4.10 cm/s, about double the speed of the large-scale low frequency Rossby wave (2.2 cm/s). TOPEX/Poseidon/Jason1 along-track sea level height estimates since January 1993, filtered interannually, propagate westward at 4.3 cm/s, verifying that observed westward propagation is about double that expected. Including the effect of the mean California current on the Rossby wave propagation does not explain the discrepancy but rather slightly increases it. Because of the westward propagation, interannual variations in alongshore geostrophic surface current are proportional to the time derivative of sea level. This means that such large scale interannual current variability can be monitored with appropriate lag, by the time derivative of coastal sea level. The anomalous alongshore flow advects particles, the anomalous alongshore particle displacement being proportional to sea level. Since nutrient concentration is lower in the south, the anomalous alongshore displacement results in lower nutrient concentration when sea level is anomalously high and higher nutrient concentration when the sea level is anomalously low. Vertical displacement also results in a similar relationship between nutrients and sea level. The anomalous alongshore and vertical particle displacements associated with the Rossby waves also act on the mean temperature and salinity fields to produce temperature and salinity anomalies. Theory suggests that these anomalies should be proportional to the anomalous dynamic height. Consistent with this, observed salinity anomalies at depths of 100-200 m are well correlated with dynamic height anomalies. At depths greater than 200 m the observed anomalies are small and, consistent with a smaller signal to noise ratio, the correlation falls. At depths shallower than 100 m the correlation between salinity and dynamic height anomalies also falls rapidly. The flow anomalies can similarly be used to explain the temperature fluctuations except that the correlation between temperature and dynamic height fluctuations does not fall rapidly in the surface layer as in the salinity case.
Show less
Date Issued: 2007
Identifier: FSU_migr_etd-0684
Format: Thesis

Title: Statistical Prediction of Tropical Cyclone Intensity Using Dynamical and Thermodynamical Inner-Core Parameters Derived from Hwrf Analysis and Forecasts.
Creator: Zelinsky, David A., Co-, T.N. Krishnamurti, Co-, Paul Ruscher, Misra, Vasu, Hart, Robert, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: A new multiple linear regression model for short range tropical cyclone intensity prediction is developed. Four new dynamical and thermodynamical predictors based on HWRF output are considered: (1) the horizontal advection of relative angular momentum, (2) energy exchange from the divergent to the rotational kinetic energy (Psi-Chi interactions), (3) the conversion of shear vorticity to curvature vorticity, and (4) the vertical differential of heating in the complete potential vorticity...
Show moreA new multiple linear regression model for short range tropical cyclone intensity prediction is developed. Four new dynamical and thermodynamical predictors based on HWRF output are considered: (1) the horizontal advection of relative angular momentum, (2) energy exchange from the divergent to the rotational kinetic energy (Psi-Chi interactions), (3) the conversion of shear vorticity to curvature vorticity, and (4) the vertical differential of heating in the complete potential vorticity equation. Predictors were calculated using Hurricane Research Weather and Forecast (HWRF) model initial fields. Each predictor was determined to exhibit a statistically significant relationship with 12 hour intensity change in tropical cyclones by an F-test. The predictors were then used as the basis for a multiple linear regression model, following the methodology of the operational Statistical Hurricane Intensity Prediction Scheme (SHIPS). Four additional predictors, intended to represent basic storm information and environmental conditions, were included in the development of a second model. Retrospective forecasts of hurricanes in 2004, 2005, and 2006 were created for both models, and compared to operational SHIPS and HWRF forecasts. Despite relying on HWRF fields for the calculation of predictors, the new model produces better forecasts than HWRF for short term (less than 48-hr) forecasts. Additional methods were developed to extend forecasts beyond 48 hours. This resulted in a systematic improvement of HWRF forecasts. It is proposed that the new model could be used operationally as a new version of the "early" HWRF.
Show less
Date Issued: 2011
Identifier: FSU_migr_etd-0585
Format: Thesis

Title: Effect Hypoxia Has on Feeding and Egg Production Rates of Acartia Tonsa Dana 1849 (Copepoda: Calanoida).
Creator: Sedlacek, Chris, Marcus, Nancy, Thistle, David, Kostka, Joel, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Low oxygen conditions in the water column or hypoxia occur in estuaries and impact more than just the obvious commercially important species. Copepods are an important link in the food web and the influence of hypoxia upon them is relatively unstudied. Using the copepod Acartia tonsa, a study of the impact of hypoxia on egg production and feeding was conducted. A. tonsa decreased egg production at lower dissolved oxygen concentrations (DO), with the lowest egg production occurring at 0.53-ml...
Show moreLow oxygen conditions in the water column or hypoxia occur in estuaries and impact more than just the obvious commercially important species. Copepods are an important link in the food web and the influence of hypoxia upon them is relatively unstudied. Using the copepod Acartia tonsa, a study of the impact of hypoxia on egg production and feeding was conducted. A. tonsa decreased egg production at lower dissolved oxygen concentrations (DO), with the lowest egg production occurring at 0.53-ml/l O2 concentration. However as the DO decreased the amount of chlorophyll a in the gut of the copepods increased. Also as DO decreased the number of fecal pellets decreased, indicating that feeding was being suppressed. Another experiment was conducted to determine if by increasing food concentration the affect of hypoxia could be mitigated. The results indicate that increased food did not offset the impact hypoxia has on egg production of A. tonsa. These results suggest that as A. tonsa experiences hypoxia in the wild, population numbers will decrease. Thus if hypoxic conditions increase in scope and duration declines in copepod abundance may very well lead to a decline in the abundance of species that depend on them as food. These species may be of commercial importance.
Show less
Date Issued: 2003
Identifier: FSU_migr_etd-0285
Format: Thesis

Title: The Impacts of Macrobenthos on the Rates and Pathways of Organic Matter Mineralization in Two Coastal Marine Ecosystems of the Southeastern United States.
Creator: Smith, April Christine, Kostka, Joel E., Balkwill, David, Thistle, David, Marcus, Nancy, Devereux, Richard, Furukawa, Yoko, Department of Earth, Ocean and Atmospheric Sciences,...
Show moreSmith, April Christine, Kostka, Joel E., Balkwill, David, Thistle, David, Marcus, Nancy, Devereux, Richard, Furukawa, Yoko, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Show less
Abstract/Description: Coastal ecosystems are among the most productive in the world, and they serve as an invaluable resource to society. Despite many decades of biogeochemical research in the coastal zone, carbon and nutrient budgets remain uncertain largely due to the inherent complexity and spatiotemporal variability observed in coastal ecosystems. This dissertation addresses the rates, pathways, and microorganisms responsible for organic-matter mineralization and nutrient release in the sediments of coastal...
Show moreCoastal ecosystems are among the most productive in the world, and they serve as an invaluable resource to society. Despite many decades of biogeochemical research in the coastal zone, carbon and nutrient budgets remain uncertain largely due to the inherent complexity and spatiotemporal variability observed in coastal ecosystems. This dissertation addresses the rates, pathways, and microorganisms responsible for organic-matter mineralization and nutrient release in the sediments of coastal marine ecosystems. In particular, the research herein focuses on the role of macrobenthos and spatial/ temporal variability in impacting organic matter and nutrient cycles in such ecosystems. The common theme throughout the dissertation research was to combine ecology with biogeochemistry to explore the impacts of benthic organisms in the macroscale on microbial processes that mediate organic matter mineralization and nutrient release over the microscale. Sulfate-reducing prokaryotes (SRP) play a key role in carbon and nutrient cycles of coastal marine, vegetated ecosystems, but interactions of SRP communities with aquatic plants remain little studied. In the subtidal zone of Santa Rosa Sound, Florida, SRP abundance, activity, and community composition were studied in relation to sediment geochemical gradients and plant growth state in a Thalassia testudinum seagrass bed and in adjacent unvegetated areas (Chapter 1). The community composition of SRP was determined using restriction fragment length polymorphism (RFLP) screening and amino acid sequence comparisons inferred from partial dissimilatory bisulfite reductase (dsrA and B) genes that were PCR-amplified and cloned from DNA extracted from sediment samples. Our results indicate that seagrass growth state affects the abundance and activity of SRP, while SRP community composition remains relatively stable across the environmental parameters tested. Sequence data from this study may be used to direct future cultivation efforts and to design new genetic probes for sulfate-reducers in seagrass sediments. The remaining dissertation research focused on a second coastal marine ecosystem, the saltmarsh, on Skidaway Island near Savannah, Georgia. The Georgia saltmarsh contrasts with seagrass beds from the west coast of Florida in that it exists in the intertidal zone, contains a large tidal range of 2-3 m, and the sediments are exposed to extensive burrowing and feeding activities by macrofauna. In addition, larger seasonal change may be observed in the Georgia marsh because it is intertidal and exposed to slightly larger annual temperature extremes. In chapter two, extensive biogeochemical field characterization was combined with state-of-the-art diagenetic modeling to elucidate feedbacks between macrobenthic organisms (macrophyte plants, bioturbating macrofauna) and the controls of organic matter mineralization in saltmarsh sediments. A multicomponent, inverse model was used to support the field work by quantifying properties and processes that in some cases could not be experimentally determined. Modeled rates of organic matter diagenesis were determined by attempting to find the best agreement with measured profiles of major redox species. Results indicated that sulfate reduction is the dominant degradation pathway for sites with less bioturbation, while iron reduction outcompeted sulfate reduction where intense bioturbation activity caused the rapid recycling of Fe(III)-oxyhydroxides. These results were fairly consistent across seasons, however, the magnitude of degradation rates decreased dramatically in the winter, and microbial sulfate reduction was more greatly affected by changes in temperature than microbial iron reduction. The objective of the third and final study was to scale up biogeochemical measurements over an entire ecosystem (saltmarsh basin) in order to address spatial variability that has confounded estimates of organic matter and nutrient mineralization at the whole ecosystem level. A 100,000 m2 area of Georgia marsh was mapped using a combination of aerial photography, Geographic Information Systems (GIS), and localized identification of plant types. Major habitats were delineated according to the predominant vegetation, including the short form of Spartina alterniflora (SS), the tall form of S. alterniflora (TS) and unvegetated creekbank (CB). Spatial variability was addressed across all major habitats with a statistically-sound experimental design to carry out determinations of porewater and solid-phase geochemistry, sulfate reduction rates (SRR), bacterial abundances, macrofaunal burrow size/density, plant stem height/density, and above/belowground plant biomass. Habitat type had a large influence on the rates and pathways of carbon oxidation. Consideration of spatial variability revealed that overall carbon oxidation rates in saltmarsh ecosystems may be higher than previously thought. Surprisingly, microbial Fe(III) reduction (and not sulfate reduction) was observed to be the predominant terminal-electron-accepting process coupled to carbon oxidation for the majority of the marsh basin studied. Together with the observation that most of the Georgia marsh studied was not sulfidic, results indicate that our perceptions of the redox poise, and the impacts of redox poise on biogeochemical cycles, need to be revised for marsh ecosystems taking into account spatial variability driven by macrobenthic activities. Typically, coastal sediments rapidly become anaerobic just below the sediment surface, and the flux of oxidants into sediments is limited. Under these conditions, anaerobic bacteria are responsible for the majority of organic matter remineralization. Increased solute and particle transport via macroorganismal activities (bioturbation, bioirrigation, and phytoirrigation) aids in mixing reactants throughout sediments, thereby encouraging microbial activities, and increasing organic matter remineralization rates. The following research employed an array of new and diverse multidisciplinary approaches from molecular biological techniques and GIS mapping to state-of-the-art diagenetic modeling in order to elucidate the impacts of macrobenthos on carbon and nutrient cycles mediated by anaerobic microorganisms in coastal marine ecosystems. In all three studies, geochemical parameters indicated that bacterial activities were stimulated in vegetated sediments, while saltmarsh studies revealed that macrofaunal burrows strongly influenced the pathways of terminal electron acceptor (TEA) usage. The uncertainty of current estimates of carbon and nitrogen cycling in saltmarsh habitats indicates the need for a more comprehensive approach to address the spatial variability that exists in these habitats. From the research reported in this dissertation, it is clear that macrobenthos have a profound impact on the rates and pathways of organic matter mineralization and that the resulting spatial variability in sediment biogeochemical cycles must be incorporated into future studies that attempt to determine elemental budgets in coastal marine ecosystems.
Show less
Date Issued: 2004
Identifier: FSU_migr_etd-0343
Format: Thesis

Title: The Bering Strait and the Southern Ocean Winds' Grip on the World Climate.
Creator: De Boer, Agatha M., Nof, Doron, Hunter, Christopher, Burnett, William, Clarke, Alan J., Speer, Kevin, Weatherly, Georges L., Department of Earth, Ocean and Atmospheric Sciences,...
Show moreDe Boer, Agatha M., Nof, Doron, Hunter, Christopher, Burnett, William, Clarke, Alan J., Speer, Kevin, Weatherly, Georges L., Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Show less
Abstract/Description: The Bering Strait's Grip On The World Climate: The Holocene interglacial period of the last 10,000 years and the penultimate interglacial ~125,000 years ago have been characterized by distinctly stable climates. During the intervening glacial period, climate records are marked by rapid large-amplitude oscillations, general known as Dansgaard-Oeschger events. These millennial-scale cycles are generally believed to be a result of freshwater anomalies in the North-Atlantic, followed by a...
Show moreThe Bering Strait's Grip On The World Climate: The Holocene interglacial period of the last 10,000 years and the penultimate interglacial ~125,000 years ago have been characterized by distinctly stable climates. During the intervening glacial period, climate records are marked by rapid large-amplitude oscillations, general known as Dansgaard-Oeschger events. These millennial-scale cycles are generally believed to be a result of freshwater anomalies in the North-Atlantic, followed by a reorganization of the thermohaline circulation. Here, we propose that such long lasting instabilities in the thermohaline circulation are only possible during glacial periods when the Bering Strait (BS) is closed. A semi-global analytical ocean model (which includes both wind and thermohaline processes) is used to show that, during interglacial periods (when the BS is open) perturbations in North Atlantic Deep Water (NADW) formation are rapidly damped out because of a novel BS freshwater feedback mechanism. This new feedback mechanism is due to the strong winds in the Southern Ocean (SO) which, with an open BS, quickly [O(10)years)] flush any low salinity anomalies out of the Atlantic and into the Pacific Ocean. During glacial periods, the stabilizing feedback is prevented by the closure of the BS which traps the anomalies within the Atlantic, causing long lasting perturbations. The sensitivity of the mean stable state to steady changes in the external forcing, namely the wind or the precipitation field, is also tested. A relevant example is a prolonged increase in precipitation due to anthropogenic warming, (predicted by global circulation models). We find that both stronger winds (especially the SO Winds) and a decrease in precipitation over the North Atlantic (NA) will lead to a new (stable) enhanced overturning. Conversely, weaker winds or increased precipitation will reduce the overturning to a slower stable state. The Island Wind-Bouyancy Paradox: In reent years, a variety of studies have suggested that the meridional overturning circulation is at least partially controlled by the Southern Ocean winds. The paraadoxical implication is that a link exists between the surface bouyancy flux to the ocean (which is needed for the density transfor4matio between surface and deep water) and the wind. These forcings have traditionally been viewed as independent drivers of the ocean circulation. Here, the paradox is formally stated in the framework of a gigantic island that lies between latitude bands free of continents (such as the land mass of the Americas). The choice of such an island on a sphere was made because it enables one to obtain analytical solutions and it circumvents the need to calculate the torque exerted on zonal sills adjacent to the island tips (e.g., the Bering Strait). The torque calculation is notoriously difficult and is avoided here by the clockwise integration which goes twice through the western boundary of the island (in opposite directions) eliminating any unknown pressure torques. The derived wind-driven overturning is shown to be consistent with Godfrey's Island Rule when the rule is extended to include the sinking or upwelling adjacent to the island. In addition, the consideration of vertical exchange in the Island Rule eliminates the need to make the level-of-no-motion assumption. The paradox is resolved quanlitatively, using salinity and temperature mixed dynamical-box models and a temperature slab model, and quantitatively, employing a numerical model. We show that in all cases the ocean stratification and thermocline depth adjust themselves to allow the overturning imposed by the wind. The salinity and temperature box model suggests that stronger southern winds will tend to weaken the virtical and horizontal salinity stratfication so that it is esier for the conversion of deep to surface water (and vice versa) to take place. A temperature slab model (i.e., y-dependent)offers a more detailed picture;stronger southern winds flatten the meridional temperature profile and shift it northwards (so that it lags the atmospheric temperature). The (process orientated) numericl model is adapted to include a thermodynamic parameterization for the surface heat and freshwater fluxes. In response to stronger southern winds, the thermocline thickens in the north, releases more heat to the atmosphere and, therefore, converts more surface to deep water.
Show less
Date Issued: 2003
Identifier: FSU_migr_etd-0336
Format: Thesis

Title: Attributing Contributions to the Seasonal Cycle of Anthropogenic Warming in a Simple Radiative- Convective Global Energy Balance Model.
Creator: Sejas, Sergio A., Cai, Ming, Ellingson, Robert G., Wu, Zhaohua, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: A simple one-dimensional seasonal atmosphere-ocean energy balance model is used to study the seasonal and latitudinal response of the model climate to a doubling of the CO2 concentration. A new climate feedback analysis method, formulated in Lu and Cai (2009a), is used to isolate contributions (partial temperature changes) of the external forcing alone and subsequent feedbacks to the total temperature change experienced by the model climate. In this study, the relative importance of the...
Show moreA simple one-dimensional seasonal atmosphere-ocean energy balance model is used to study the seasonal and latitudinal response of the model climate to a doubling of the CO2 concentration. A new climate feedback analysis method, formulated in Lu and Cai (2009a), is used to isolate contributions (partial temperature changes) of the external forcing alone and subsequent feedbacks to the total temperature change experienced by the model climate. In this study, the relative importance of the external forcing alone (the CO2 doubling), surface ice-albedo feedback, water vapor feedback, changes in poleward heat transport, changes in vertical sensible heat flux, and changes in heat storage are analyzed. The partial temperature change due to the water vapor feedback is substantially the largest contributor to the globally averaged surface warming. The ice-albedo feedback plays a smaller role, but also significantly contributes to the overall warming of the surface. The most important negative feedback, counteracting the surface warming, is the change in the vertical sensible heat flux. However, though the water vapor feedback is most responsible for the overall surface warming, it is not the feedback most responsible for the seasonal and spatial pattern of the surface warming. The climate of this model indicates that there is a surface polar warming amplification, with a maximum occurring in late summer/early fall. The feedback most responsible for this polar warming amplification and seasonal pattern in this model is the surface ice-albedo feedback, which is largest at high latitudes in summer.
Show less
Date Issued: 2011
Identifier: FSU_migr_etd-0278
Format: Thesis

Title: Impacts of Deep-Sea Carbon Sequestration and of Ciliate Epibionts on Harpacticoid Copepods.
Creator: Sedlacek, Linda, Thistle, David, Wulff, Janie, Marcus, Nancy, Huettel, Markus, Burnett, William, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: One way to slow down global warming is to reduce the amount of carbon dioxide released into the atmosphere by capturing carbon dioxide from point sources (e.g., power plants) and storing it out of contact with the atmosphere. One storage site that is being considered is the deep-sea floor. Below ~2600 m, carbon dioxide is a liquid and is denser than seawater, so carbon dioxide poured into a depression would create a carbon dioxide lake. The environmental consequences of this disposal option...
Show moreOne way to slow down global warming is to reduce the amount of carbon dioxide released into the atmosphere by capturing carbon dioxide from point sources (e.g., power plants) and storing it out of contact with the atmosphere. One storage site that is being considered is the deep-sea floor. Below ~2600 m, carbon dioxide is a liquid and is denser than seawater, so carbon dioxide poured into a depression would create a carbon dioxide lake. The environmental consequences of this disposal option are largely unknown. This study tries to address the environmental consquences by studying the effects of carbon dioxide-rich seawater on organisms at various distance from a carbon-dioxide source. Harpacticoids were chosen as the study organism because they are abundant and may be an important prey item in the deep sea. To determine if the carbon dioxide-rich seawater affected the harpacticoids, a seven metrics were used. Overall, none of the metrics indicated that exposure to carbon dioxide-rich seawater had an effect. A previous study found a very different result. A comparison of the two studies revealed that the difference in flow dynamics between the two stations in the two experiments could explain the dichotomy, raising the possibility that deep-sea benthic environments that experience slower flow may be better disposal sites. Harpacticoids in the deep-sea sometimes harbor ciliate epibionts. Their presence may influence a harpacticoid's ability to deal with the stress imposed by carbon-dioxide rich seawater. As a first step in trying to understand the harpacticoid-epibiont relationship, I identified the epibionts and determined whether or not they occurred more frequently on adults, on one host species more than the others, on one host sex more than another, or on one portion of a host more than another portion at the control site. Three epibiont species were abundant enough to analyze, Loricophrya sp., Trachelolophos sp., and Vorticella sp. Loricophrya sp. and Trachelolophos sp. individuals attached only to the antennules of Nitokra sp. and occurred significantly more often on this species than on other species. Vorticella sp. individuals attached significantly more frequently to Ameira sp. and Mesocletodes cf. irrasus than to other species. Individuals of Vorticella sp. were found attached to the side of the cephalosome, to the region of the mouth parts, and to the body between the swimming legs. Specificity in host usage was unexpected because harpacticoid individuals of a given species are sparse in the deep-sea. I did not find that any of the epibiont species occurred on one sex more than the other. One method that epibionts may use in order to be host specific is to attach to species that are relatively abundant. I then examined the potential effect that the epibionts had on their hosts. To do so, I compared the harpacticoids at the 2-m site (treatment area) and 75-m site (control area). I found that only for individuals of Nitokra sp. with individuals of Loricophrya sp. attached was there a significantly higher proportion of host individuals with epibionts in the treatment area than in the control area. None of the host species showed a difference in the average number of epibionts they carried in the control area and the treatment area. These results suggest that individuals of Nitokra sp. were capable of resisting the attachment of the first individual of Loricophrya sp., but that individuals of Nitokra sp. were unable to continue to resist after the first Loricophrya sp. individual attached. Trachelolophos sp. was always with Loricophrya sp., so for the analyses that examined the proportion of host individuals that were alive at the time of collection, the group of harpacticoids that had only Loricophrya sp. (= L.) and those with both Trachelolophos sp. and Loricophrya sp. (= L. + T.) were analyzed together (= L. and L. + T.). In the treatment area, the proportion of individuals of Nitokra sp. that were alive at the time of collection was greater when individuals of L. and L. + T. were attached than when they not. In the control area, the proportion of individuals of Ameira sp. that were alive at the time of collection was greater when individuals of Vorticella sp. were attached than when they were not. In general, the effect of the epibionts on their host harpacticoids appears to be positive, an unexpected result considering that positive effects have not been found before.
Show less
Date Issued: 2007
Identifier: FSU_migr_etd-0284
Format: Thesis

Title: The Biochemical Composition of Naupii Derived from Stored Non-Diapause and Diapause Copepod Eggs and the Biology of Diapausing Eggs.
Creator: Sedlacek, Christopher, Marcus, Nancy, Keller, Laura, Thistle, David, Huettel, Markus, Kostka, Joel, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Mariculture of fish is needed to support our ever growing global population. Copepods are a natural and beneficial source of first feed for many marine fish species, but it can be difficult to hatch enough when the fish are ready to feed. Therefore, storage of copepod eggs for use at a later date increases the potential of nauplii to be used as a commercial food source. There are two types of eggs produced by copepods: diapause and non-diapause (or subitaneous). However, little is known about...
Show moreMariculture of fish is needed to support our ever growing global population. Copepods are a natural and beneficial source of first feed for many marine fish species, but it can be difficult to hatch enough when the fish are ready to feed. Therefore, storage of copepod eggs for use at a later date increases the potential of nauplii to be used as a commercial food source. There are two types of eggs produced by copepods: diapause and non-diapause (or subitaneous). However, little is known about diapause or the effects and duration of storage, either under cold or warm temperature conditions, on the biochemical composition of nauplii. Little is also known about the development of embryos that enter diapause. Diapause requires a refractory period before development of the embryo continues. The refractory period can last for several months regardless of environmental conditions. I studied the effects of both cold storage and cold storage with the addition of antibiotics on non-diapause eggs of the copepod Acartia tonsa and duration of storage for diapause eggs produced by Centropages hamatus and compared those results to nauplii derived from non-diapause eggs. The organic components analyzed to determine if potential changes were occurring during storage were lipids, fatty acids, proteins, free amino acids, and carbohydrates as well as the percent hatch of the eggs and the dry weight of the resultant nauplii. To understand diapause, we utilized two stains, one to determine the number of nuclei present and another to determine intracellular pH of the diapausing eggs. Acartia tonsa eggs stored for up to15 days at 1°C did not indicate any change in the biochemical make-up of the resulting nauplii. The only change we observed was in the viability of the eggs, which decreased at a steady rate over time. The viability of the eggs quickly approached zero percent hatch beyond 15 days. The addition of the antibiotic oxytetracyclin at a 10% concentration did not change the naupliar biochemistry and did not increase viability over the storage time. Centropages hamatus eggs maintained a high level of viability over the course of 13 months of storage under anoxic conditions. The nauplii derived from the diapause eggs stored at 25°C had similar biochemical components regardless of the length of the storage period. My study indicates that storage of A. tonsa and C. hamatus may not affect the nutritional value of the nauplii for aquaculture purposes. We also determined that the embryos of C. hamatus stopped developing after ~7 cleavages. The diapausing embryos also maintained an intracellular pH similar to the surrounding water and acidified when beginning to develop. This is the first time the intracellular pH and only the third time the nuclei of a copepod diapausing egg has been determined. This information could allow future researchers to interrupt diapause and induce the eggs to hatch before the end of the refractory period.
Show less
Date Issued: 2008
Identifier: FSU_migr_etd-0283
Format: Thesis

Title: Assimilation of GPS Radio Occultation Observations.
Creator: Shao, Hui, Zou, Xiaolei, Navon, Ionel M., Liu, Guosheng, Ray, Peter S., Krishnamurti, T. N., Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Unlike conventional and satellite observations, the Global Positioning System (GPS) radio occultation (RO) techniques provide all-weather, high-vertical-resolution observations that require no calibration. In this dissertation, the assimilation of GPS RO data is studied using the National Centers for Environmental prediction (NCEP) three dimensional variational analysis system. Three GPS data assimilation choices are considered and compared. A set of GPS bending angle assimilation (BA)...
Show moreUnlike conventional and satellite observations, the Global Positioning System (GPS) radio occultation (RO) techniques provide all-weather, high-vertical-resolution observations that require no calibration. In this dissertation, the assimilation of GPS RO data is studied using the National Centers for Environmental prediction (NCEP) three dimensional variational analysis system. Three GPS data assimilation choices are considered and compared. A set of GPS bending angle assimilation (BA) experiments is first carried out and sensitivity of BA results to the observational weighting, the quality of the background fields, the variation of the gravity, and the vertical resolution of the GPS data are investigated. The GPS local refractivity assimilation (REF) is then conducted and compared with BA. Although REF is computationally cheaper than BA, the bias and root mean square errors of the background fields are more significantly reduced by BA than REF. Differences between GPS refractivity and bending angle assimilations are larger in thick-layered cloud systems (e.g., convective clouds in the mid-latitudes and cumulus clouds in the tropics) than in thin clouds and clear sky, which are found to be associated with the strength of horizontal gradient of the atmospheric refractivity. Aiming at achieving both accuracy and computational efficiency, a new observation operator that simulates the GPS excess phase delay is proposed and tested for GPS RO data assimilation. Using the excess phase delay, the along-track refractivity and refractivity gradient information can be included while the computational cost is kept low. Numerical results from the forward simulation and data assimilation using the excess phase delay (PHA) are compared with those of REF. PHA tends to produce a warmer and wetter model atmosphere, with finer structures and larger radii of influence than REF. Compared to GPS observations, simulations and analyses produced by PHA are more accurate than those of REF. It is also pointed out that under the assumption of the spherical symmetry of the local refractivity, the observation operator for the excess phase delay simplifies into a point scheme in which only a vertical profile of model refractivity is required.
Show less
Date Issued: 2005
Identifier: FSU_migr_etd-0301
Format: Thesis

Title: Lightning Observations during Tropical Cyclone Intensity Change: A Composite Study of Spatial and Temporal Relationships.
Creator: Austin, Marcus, Fuelberg, Henry, Hart, Robert, Ruscher, Paul, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Although tropical cyclone (TC) track forecasts have improved considerably in recent years, predicting their intensity continues to be a challenge for both meteorologists and numerical models. A storm's path is primarily influenced greatly by large-scale atmospheric circulations; however, its strength appears to be dominated both by large scale influences and small-scale mechanisms within the storm itself. Most previous research on TC intensity change has employed either numerical modeling or...
Show moreAlthough tropical cyclone (TC) track forecasts have improved considerably in recent years, predicting their intensity continues to be a challenge for both meteorologists and numerical models. A storm's path is primarily influenced greatly by large-scale atmospheric circulations; however, its strength appears to be dominated both by large scale influences and small-scale mechanisms within the storm itself. Most previous research on TC intensity change has employed either numerical modeling or diagnostic approaches using traditional meteorological parameters. Only recently have studies begun to examine electrification as a means for assessing the potential for intensification. Several papers have considered lightning as a proxy for storm intensification, mostly using data from Vaisala's National Lightning Detection Network (NLDN) and Long-Range Lightning Detection Network (LLDN). However, they mostly have examined individual TCs. This study uses LLDN data to study 45 Atlantic Basin TCs between the years 2004 and 2008. Using the National Hurricane Center's (NHC) best track dataset, lightning data are collected for each TC out to a 500 km radius. Parameters including storm intensity, intensity change, environmental vertical wind shear, storm motion, and flash count are compiled at each NHC best track position. The data at each position then are categorized in several ways, including change in intensity. These methods allow us to examine relations between composites of storm intensity/intensification and convective distribution and frequency. Distributions of cloud-to-ground (CG) flash density with respect to storm motion and speed show that lightning generally is preferred in the TCs' right front and right rear quadrants. Hurricanes produce the greatest flash densities during relatively slow forward motion, while tropical depressions and tropical storms exhibit greater flash densities during faster forward motion. Storm-relative CG flash distributions during weakening, no pressure change, and slow intensification (-5 to 0 hPa 6 h-1) exhibit the same right front and rear quadrant preference as the TC intensity categories. Flash densities are greatest during periods of faster intensification, with a nearly symmetric presentation in the inner core region. When computing flash densities with respect to environmental deep layer wind shear, TCs exhibit a strong preference for lightning in the downshear left and right quadrants of the inner core (0-100 km) and outer rainbands (100-300 km), respectively. Tropical storms and hurricanes best show this relation, with TDs exhibiting a stronger preference for lightning in the downshear right quadrant. Relatively weak wind shear produces greater flash densities in all TC intensity categories. Conversely, storms experiencing strong shear exhibit smaller flash densities in all TC categories due to the disruption of deep convection. During periods of faster intensification, maximum flash densities are located in the inner core, with weakening, no change, and slow intensification periods containing greatest density in the outer rainbands. Average flash rates and flash densities are found to be greatest for weaker TCs (tropical depressions and tropical storms) with smaller flash rates and densities in hurricanes. Considering intensity change, periods of faster intensification exhibit significantly greater flash rates than periods of weakening, no pressure change, and slow intensification. Only weak relations are found between flash rates and intensity change, with the strongest relationship occurring when lightning lags (occurs after) the pressure change period. Lightning preceding (occurring before) the pressure change period exhibits the weakest relationships in all TC intensities. Correlations between CG lightning and sustained wind speed indicate that there is no preferred timing between maximum lightning activity and maximum sustained winds. Instead, maximum correlations occur during periods when greatest lightning activity both precedes and lags the maximum sustained wind. These results indicate that lightning is poorly correlated with intensity change and can be regarded as a poor choice for intensity forecasting.
Show less
Date Issued: 2011
Identifier: FSU_migr_etd-0261
Format: Thesis

Title: Abundance of Bottlenose Dolphins (Tursiops Truncatus) in the Big Bend of Florida, St. Vincent Sound to Alligator Harbor.
Creator: Tyson, Reny Blue, Nowacek, Douglas, Dewar, William, Wells, Randy, Chanton, Jeffrey, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Mark-recapture surveys implementing photographic identification techniques were used to estimate the abundance of bottlenose dolphins in an area of the Big Bend of Florida, stretching from St. Vincent Sound to Alligator Harbor, in the summer of 2007 and winter of 2008. The current population size of individuals in this region is unknown as the most recent abundance estimates were calculated based on aerial surveys conducted in 1993. Recent large scale mortality events, together with an...
Show moreMark-recapture surveys implementing photographic identification techniques were used to estimate the abundance of bottlenose dolphins in an area of the Big Bend of Florida, stretching from St. Vincent Sound to Alligator Harbor, in the summer of 2007 and winter of 2008. The current population size of individuals in this region is unknown as the most recent abundance estimates were calculated based on aerial surveys conducted in 1993. Recent large scale mortality events, together with an increasing potential for human impacts in this area, warrant an updated and increased understanding of the abundance and stock structure of dolphins in this region. Because the region is large and recent work here suggests that at least two distinct communities exist in these waters, the region was divided into the two areas in which these communities appear to reside (St. Vincent Sound/Apalachicola Bay and St. George Sound/Alligator Harbor) and independent estimates of abundance were calculated for each area and each season. Closed-population models in the program CAPTURE were used to derive the estimates of abundance and the assumptions underlying each model were examined. The estimates calculated from the models selected as being the most appropriate for each data set were similar for each survey area for each season: in the St. Vincent Sound/Apalachicola Bay survey area 182 ± 58 animals inhabited the survey area in the summer and 178 ± 77 animals in the winter; in the St. George Sound/Alligator Harbor survey area 365 ± 164 animals inhabited the survey area in the summer and 359 ± 87 animals in the winter. Results from this study also provided further evidence that at least two communities reside in these waters as only 2.4% of animals captured during the study were captured in both survey areas. If indeed two communities exist in these waters, it appears that site-fidelity and/or residence patterns of individuals may differ between them; in the St. Vincent Sound/Apalachicola Bay survey area 49.6% of the total animals captured were captured more than once and 29.6% were captured both seasons, while in the St. George Sound/Alligator Harbor survey area 35.3% were captured more than once and 13.8% of animals were captured both seasons. In addition, it appears that the St. George Sound/Alligator Harbor survey area supports a greater number of transient animals than the St. Vincent Sound/Apalachicola survey area (46.1% of distinctive animals were seen only once versus 29.9% respectively). This may be due in part to this survey area being more accessible to the open waters of the Gulf of Mexico than the St. Vincent Sound/Apalachicola Bay survey area, which is more protected by barrier islands. The results provided here can be used by the National Marine Fisheries Service to aid in their stock-assessment process and help in the management of the animals in this region.
Show less
Date Issued: 2008
Identifier: FSU_migr_etd-0323
Format: Thesis

Title: Post-Processing Improvements to an Ensemble Forecast Using an Archive of Past Forecasts and Verifications.
Creator: Allgood, Adam Douglas, Ahlquist, Jon E., Krishnamurti, T. N., Zou, Xiaolei, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Ensemble forecasts are the primary tool used operationally to assess forecast uncertainty. Studies of ensemble forecasts, however, have shown that forecast verifications too frequently lie outside of the ensemble's range of possibilities, meaning that uncorrected ensemble forecasts suggest more confidence than is justified. To make ensemble forecasts more representative of the actual range of possibilities, we present a technique to post-process ensemble forecasts by replacing member...
Show moreEnsemble forecasts are the primary tool used operationally to assess forecast uncertainty. Studies of ensemble forecasts, however, have shown that forecast verifications too frequently lie outside of the ensemble's range of possibilities, meaning that uncorrected ensemble forecasts suggest more confidence than is justified. To make ensemble forecasts more representative of the actual range of possibilities, we present a technique to post-process ensemble forecasts by replacing member forecasts with verifications of what actually occurred when past forecasts were similar. To maximize the information that can be extracted from an archive of past forecasts and verifications, we allow analogs to come from different locations in space. We evaluated our procedure to post-process NCEP ensemble precipitation forecasts for the United States for 15-day periods in July 2005 and January 2006. Our analog correction technique significantly improved the ensemble's ability to forecast the probability of precipitation, in particular correcting the NCEP Global Ensemble's ``wet' bias at low precipitation amounts. Brier Skill Scores for 6-hour accumulated precipitation during the winter indicated that uncorrected ensemble forecasts were less skillful at predicting the probability of precipitation than forecasting zero precipitation as indicated by negative Brier Skill Scores (roughly -2.5). Post processed forecasts had Brier Skill Scores as high as 0.34. The tendency of the ensemble to underforecast heavy precipitation events, however, was not well corrected by our post-processing technique. Examinations of analog locations during heavy precipitation events indicated that analogs were taken from regions where precipitation patterns differed from those at the forecast point. This indicates that analogs must be chosen using more information than merely the similarity of ensemble precipitation forecasts to past forecasts.
Show less
Date Issued: 2007
Identifier: FSU_migr_etd-0173
Format: Thesis

Title: Improving Hurricane Intensity Forecasts in a Mesoscale Model via Microphysical Parameterization Methods.
Creator: Albers, Cerese Marie, Krishnamurti, Tiruvalam N., Liu, Guosheng, Ruscher, Paul, Hood, Robbie, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Accurate hurricane intensity prediction is at the forefront of atmospheric science today, and improvements to mesoscale modeling of these storms continue to be major components of refining the accuracy of intensity forecasting. The primary goal of this study is to improve mesoscale modeling of hurricane intensity via the comparison of field campaign observations of Hurricane Erin 2001 from the Fourth Convection And Moisture Experiment (CAMEX-4) and Hurricane Dennis 2005 from the Tropical...
Show moreAccurate hurricane intensity prediction is at the forefront of atmospheric science today, and improvements to mesoscale modeling of these storms continue to be major components of refining the accuracy of intensity forecasting. The primary goal of this study is to improve mesoscale modeling of hurricane intensity via the comparison of field campaign observations of Hurricane Erin 2001 from the Fourth Convection And Moisture Experiment (CAMEX-4) and Hurricane Dennis 2005 from the Tropical Cloud Systems and Processes (TCSP) mission with simulated results of improved microphysical parameterization in a mesoscale model that utilizes the Krishnamurti, et al (1991) technique of rain rate initialization (RRI). Comparison of the simulated results with field observations collocated with satellite observations provides a way to validate many different aspects of the simulated hurricane's structure and intensity. The mesoscale model used in this research is the Weather Research & Forecasting (WRF) model version 2.1 (ARW). Much of the existing microphysical parameterization of this model is built from results of mid-latitude observations. Substantial improvement to the model's intensity forecasting in the tropics can be made via proper parameterization of the model microphysics for hurricanes. With a foundation of results from other hurricane mesoscale modeling initial/boundary conditions, dynamics and physics studies, basic options for modeling hurricanes Erin (2001) and Dennis (2005) are chosen and held constant during a series of microphysical sensitivity experiments for each storm. These are specifically designed to isolate the individual effects of altering one microphysical parameter at a time on the hurricane's intensity forecast and are carried out in a doubly or triply nested way. The initial and boundary conditions used in the innermost grid with finer resolution are obtained from the respective outermost grids where rain rate initialization is invoked. All of the results are illustrated for the highest-resolution innermost domain, which is integrated using an explicit microphysics scheme. Each of these experiments are integrated for a forty-eight hour forecast period, adequately capturing the mature and intensification stages of the two hurricanes. Skill scores are obtained from the results of the two sets of experiments. Root Mean Square Errors (RMSE) and Anomaly Correlations (AC) are computed by comparing the model output of each experiment to NCEP's final analysis (fnl) available at one-degree horizontal resolution and six-hour temporal resolution interpolated to the respective model grid. Taking into account the way that each experiment performs in terms of simulated storm intensity as well as optimized RMSE and AC, the optimal combination of microphysical processes (i.e. melting, evaporation, fall speed of hydrometeors) for each storm is determined. Then a final forty-eight hour forecast of each hurricane is made utilizing this optimal microphysical parameterization combination. The results from each final run are compared to observations, skill scores are computed, and the final intensity improvements for both hurricanes Erin and Dennis are shown. The results of this study strengthen the evidence that RRI and proper microphysical parameterization in mesoscale hurricane modeling are both useful and effective techniques, and combine to improve hurricane intensity forecasting in a mesoscale model.
Show less
Date Issued: 2007
Identifier: FSU_migr_etd-0156
Format: Thesis

Title: Dissipation of Mesoscale Energy by Vortex-Topography Interaction.
Creator: Bishnu, Siddhartha, Dewar, William K., Chassignet, Eric P., Clarke, Allan J., Kopriva, David A., Florida State University, College of Arts and Sciences, Department of Earth,...
Show moreBishnu, Siddhartha, Dewar, William K., Chassignet, Eric P., Clarke, Allan J., Kopriva, David A., Florida State University, College of Arts and Sciences, Department of Earth, Ocean, and Atmospheric Science
Show less
Abstract/Description: Energy is introduced into the oceans primarily at large scales by means of wind, tides and surface buoyancy forcing. This energy is transferred to the smaller mesoscale eld through the geostrophic instability processes. The mesoscale eld appears not to have accelerated appreciably over the last several decades, so we can assume that the mesoscale loses energy at roughly the same rate it receives energy. Interestingly, how the mesoscale loses energy is not quite clear. We have been exploring...
Show moreEnergy is introduced into the oceans primarily at large scales by means of wind, tides and surface buoyancy forcing. This energy is transferred to the smaller mesoscale eld through the geostrophic instability processes. The mesoscale eld appears not to have accelerated appreciably over the last several decades, so we can assume that the mesoscale loses energy at roughly the same rate it receives energy. Interestingly, how the mesoscale loses energy is not quite clear. We have been exploring topographic interaction as a pathway by which the mesoscale may lose energy to unbalanced forward cascading flows. To demonstrate this phenomenon, an approximate model theory is developed which consists of solving a reduced set of the momentum equations in density coordinates for any topographic conguration. The equations are solved using a high order spectral element technique and the results are similar to already published MITgcm simulations.
Show less
Date Issued: 2017
Identifier: FSU_FALL2017_Bishnu_fsu_0071N_14263
Format: Thesis

Title: Local Cooling Despite Global Warming.
Creator: Girihagama, Lakshika Nilmini Kumari, Nof, Doron, Tam, Christopher K. W., Bourassa, Mark Allan, Clarke, Allan J., Sura, Philip, Ewald, Brian D., Florida State University, College...
Show moreGirihagama, Lakshika Nilmini Kumari, Nof, Doron, Tam, Christopher K. W., Bourassa, Mark Allan, Clarke, Allan J., Sura, Philip, Ewald, Brian D., Florida State University, College of Arts and Sciences, Program in Geophysical Fluid Dynamics
Show less
Abstract/Description: How much warmer is the ocean surface than the atmosphere directly above it? Part 1 of the present study offers a means to quantify this temperature difference using a nonlinear one-dimensional global energy balance coupled ocean–atmosphere model ("Aqua Planet"). The significance of our model, which is of intermediate complexity, is its ability to obtain an analytical solution for the global average temperatures. Preliminary results show that, for the present climate, global mean ocean...
Show moreHow much warmer is the ocean surface than the atmosphere directly above it? Part 1 of the present study offers a means to quantify this temperature difference using a nonlinear one-dimensional global energy balance coupled ocean–atmosphere model ("Aqua Planet"). The significance of our model, which is of intermediate complexity, is its ability to obtain an analytical solution for the global average temperatures. Preliminary results show that, for the present climate, global mean ocean temperature is 291.1 K whereas surface atmospheric temperature is 287.4 K. Thus, the surface ocean is 3.7 K warmer than the atmosphere above it. Temporal perturbation of the global mean solution obtained for "Aqua Planet" showed a stable system. Oscillation amplitude of the atmospheric temperature anomaly is greater in magnitude to those found in the ocean. There is a phase shift (a lag in the ocean), which is caused by oceanic thermal inertia. Climate feedbacks due to selected climate parameters such as incoming radiation, cloud cover, and CO2 are discussed. Warming obtained with our model compares with Intergovernmental Panel on Climate Change's (IPCC) estimations. Application of our model to local regions illuminates the importance of evaporative cooling in determining derived air-sea temperature offsets, where an increase in the latter increases the systems overall sensitivity to evaporative cooling. In part 2, we wish to answer the fairly complicated question of whether global warming and an increased freshwater flux cause Northern Hemispheric warming or cooling. Starting from the assumption of the ocean as the primary source of variability in the Northern hemispheric ocean–atmosphere coupled system, we employed a simple non–linear one–dimensional coupled ocean–atmosphere model similar to the "Aqua Planet" model but with additional advective heat transports. The simplicity of this model allows us to analytically predict the evolution of many dynamical variables of interest such as, the strength of the Atlantic Meridional overturning circulation (AMOC), temperatures of the ocean and atmosphere, mass transports, salinity, and ocean–atmosphere heat fluxes. Model results show that a reduced AMOC transport due to an increased freshwater flux causes cooling in both the atmosphere and ocean in the North Atlantic (NA) deep–water formation region. Cooling in both the ocean and atmosphere can cause a reduction of the ocean–atmosphere temperature difference, which in turn reduces heat fluxes in both the ocean and atmosphere. For present day climate parameters, the calculated critical freshwater flux needed to arrest AMOC is 0.14 Sv. Assuming a constant atmospheric zonal flow, there is both minimal reduction in the AMOC strength, as well as minimal warming of the ocean and atmosphere. This model provides a conceptual framework for a dynamically sound response of the ocean and atmosphere to AMOC variability as a function of increased freshwater flux. The results are qualitatively consistent with numerous realistic coupled numerical models of varying complexity.
Show less
Date Issued: 2015
Identifier: FSU_2015fall_Girihagama_fsu_0071E_12927
Format: Thesis

Title: Characterization of Metal-Reducing Microbial Communities from Acidic Subsurface Sediments Contaminated with Uranium(VI).
Creator: Edwards, Ellen Mclain, Kostka, Joel E., Balkwill, David, Krumholz, Lee R., Burnett, Bill, Chanton, Jeff, Department of Earth, Ocean and Atmospheric Sciences, Florida State...
Show moreEdwards, Ellen Mclain, Kostka, Joel E., Balkwill, David, Krumholz, Lee R., Burnett, Bill, Chanton, Jeff, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Show less
Abstract/Description: Extraction and processing of uranium ore during the Cold-War era have left many sites around the world contaminated with uranium. Leaching of uranium into the groundwater is of major concern because oxidized uranium, U(VI), is toxic, soluble, and therefore mobile in subsurface environments where the majority of contamination resides. Uranium [U(VI)] can be immobilized from water by its reduction from UO22+ to insoluble U(IV) oxide, and biostimulation by the addition of carbon substrates has...
Show moreExtraction and processing of uranium ore during the Cold-War era have left many sites around the world contaminated with uranium. Leaching of uranium into the groundwater is of major concern because oxidized uranium, U(VI), is toxic, soluble, and therefore mobile in subsurface environments where the majority of contamination resides. Uranium [U(VI)] can be immobilized from water by its reduction from UO22+ to insoluble U(IV) oxide, and biostimulation by the addition of carbon substrates has been shown to stimulate the microbial reduction of U(VI) in contaminated subsurface environments. However, in order to develop effective bioremediation strategies for contaminant metals, the microbial communities and mechanisms controlling metal reduction need to be better understood, especially in acidic subsurface environments. This dissertation research used an array of microbiological and geochemical techniques to examine metal reduction in materials from the U.S. Department of Energy (DOE) Natural and Accelerated Bioremediation Research (NABIR)'s Field Research Center (FRC), in Oak Ridge, Tennessee, where subsurface sediments are cocontaminated with high levels of U(VI) and nitrate. The combination of low pH and high concentrations of nitrate and radionuclides in an aerobic subsurface environment is representative of many sites within the U.S. nuclear weapons complex managed by the DOE. Thus, results are not only important for bioremediation research at the FRC but can also be applied to other sites. Iron(III)-reducing bacteria (FeRB) have been demonstrated to rapidly catalyze U(VI) reduction and Fe(III) is an abundant electron acceptor in uranium-contaminated subsurface sediments. Thus, FeRB communities were the focus of this dissertation. The abundance, diversity, and activity of indigenous metal-reducing microbial communities likely to contribute to uranium reduction was examined in the field and under more controlled conditions in the laboratory. In chapter one, a combination of cultivation-dependent and cultivation-independent microbiological techniques were utilized to characterize metal-reducing bacteria in FRC subsurface sediments. Iron(III)-reducing enrichment cultures were initiated from pristine and contaminated (high in uranium, nitrate; low pH) subsurface sediments at pH 7 and pH (4-5). In selected enrichments, nitrate contamination was removed from the sediment by washing. Using a most probable number (MPN) approach and a range of different carbon sources (glycerol, acetate, lactate, or glucose), sediments of lower pH typically yielded lower counts of FeRB except when glucose was utilized as an electron donor in acidic enrichments. Phylogenetic analysis of the 16S rRNA gene sequences extracted from the highest positive MPN dilutions revealed that the predominant members of Fe(III)-reducing consortia cultured from pristine background sediments were closely related to the family Geobacteraceae, whereas a recently characterized Fe(III)-reducer (Anaeromyxobacter) and organisms not previously shown to reduce Fe(III) (Paenibacillus, Brevibacillus) predominated the Fe(III)-reducing consortia of contaminated sediments. Analysis of enrichment cultures using terminal restriction fragment length polymorphism (T-RFLP) strongly supported the cloning and sequencing results. Enrichment cultures of Fe(III)-reducers from contaminated sites were also shown to rapidly reduce millimolar amounts of U(VI) in comparison to killed controls. Using DNA extracted directly from the subsurface sediments, quantitative analysis of 16S rRNA gene sequences with MPN-PCR indicated that Geobacteraceae sequences were one to two orders of magnitude less abundant in contaminated as compared to pristine environments. In contrast, Anaeromyxobacter sequences were more abundant in contaminated sediments. Thus, results from a combination of cultivation-based and cultivation-independent approaches indicate that the abundance/ community composition of Fe(III)-reducing consortia in subsurface sediments is dependent upon geochemical parameters (pH, nitrate concentration) and microorganisms capable of producing spores (gram positives) or spore-like bodies (Anaeromyxobacter) were representative of acidic subsurface environments. In chapter two, microbial communities were studied in sediment microcosms under near in situ conditions in order to establish rates of respiration and to assess which environmental parameters might be governing activity. Rates of nitrate reduction, metal reduction, and electron donor utilization were measured in acidic subsurface sediments across a range of environmental variables (pH, nitrate) relevant to bioremediation. Microbial activity was minimal at pH 5 or below and in the absence of added electron donor, indicating that acidity is a master variable controlling microbial metabolism in FRC sediments, while high nitrate concentrations were not found to be toxic to microorganisms. In microcosms of neutral pH sediment and neutralized acidic sediment, similar, rapid rates of terminal-electron-accepting pathways were observed. The pathways of nitrate reduction were dictated by sediment pH, as denitrification predominated in glucose-amended sediments originating from neutral pH zones, whereas in neutralized acidic microcosms, metabolism shifted to dissimilatory nitrate reduction (to ammonium). Electron donors were determined to stimulate microbial metabolism leading to metal reduction in the following order: glucose > ethanol > lactate > hydrogen. A mass balance of carbon equivalents was obtained in glucose- and ethanol-amended microcosms. In neutralized acidic sediments amended with glucose, 50 to 60 % of carbon equivalents were recovered as fermentation products (mainly as acetate) and glucose-amended microcosms showed the highest iron reduction activity, while the extended presence of ethanol seemed to hinder iron reduction. The presence of bicarbonate greatly increased both nitrate and iron reduction activity in glucose-amended microcosms, more so than raising the pH by washing. Washing did increase iron reduction in glucose-amended microcosms as compared to neutralized acidic sediments, indicating that soluble toxins may somehow decrease iron reduction potential. ethanol > lactate > hydrogen. A mass balance of carbon equivalents was obtained in glucose- and ethanol-amended microcosms. In neutralized acidic sediments amended with glucose, 50 to 60 % of carbon equivalents were recovered as fermentation products (mainly as acetate) and glucose-amended microcosms showed the highest iron reduction activity, while the extended presence of ethanol seemed to hinder iron reduction. The presence of bicarbonate greatly increased both nitrate and iron reduction activity in glucose-amended microcosms, more so than raising the pH by washing. Washing did increase iron reduction in glucose-amended microcosms as compared to neutralized acidic sediments, indicating that soluble toxins may somehow decrease iron reduction potential. lactate > hydrogen. A mass balance of carbon equivalents was obtained in glucose- and ethanol-amended microcosms. In neutralized acidic sediments amended with glucose, 50 to 60 % of carbon equivalents were recovered as fermentation products (mainly as acetate) and glucose-amended microcosms showed the highest iron reduction activity, while the extended presence of ethanol seemed to hinder iron reduction. The presence of bicarbonate greatly increased both nitrate and iron reduction activity in glucose-amended microcosms, more so than raising the pH by washing. Washing did increase iron reduction in glucose-amended microcosms as compared to neutralized acidic sediments, indicating that soluble toxins may somehow decrease iron reduction potential. hydrogen. A mass balance of carbon equivalents was obtained in glucose- and ethanol-amended microcosms. In neutralized acidic sediments amended with glucose, 50 to 60 % of carbon equivalents were recovered as fermentation products (mainly as acetate) and glucose-amended microcosms showed the highest iron reduction activity, while the extended presence of ethanol seemed to hinder iron reduction. The presence of bicarbonate greatly increased both nitrate and iron reduction activity in glucose-amended microcosms, more so than raising the pH by washing. Washing did increase iron reduction in glucose-amended microcosms as compared to neutralized acidic sediments, indicating that soluble toxins may somehow decrease iron reduction potential. For the first time, rates of metal reduction and electron donor utilization were measured in acidic subsurface sediments across a range of environmental variables (pH, nitrate) relevant to bioremediation. In concurrence with previous studies of neutrophilic uranium-contaminated subsurface environments, metal reduction in the acidic subsurface did not occur until after nitrate was depleted to low levels in response to pH neutralization and carbon substrate addition. Through quantification of the rates and pathways of terminal-electron-accepting pathways in acidic subsurface sediments, we provide important inputs for reaction-based biogeochemical models that will greatly aid in the development of in situ radionuclide remediation strategies. In chapter 3, a pure culture of Fe(III)-reducing bacteria isolated from the FRC subsurface was further examined for its ability to reduce U(VI). Uranium measurements were conducted using a Kinetic Phosphorescence Analyzer, which was cross-calibrated using alpha spectrometry. The uranium reduction ability of isolate FRC32, was compared to a known uranium-reducing organism, Geobacter metallireducens. FRC32 was tested under various cultivation conditions, including a range of uranium and cell concentrations and up to 90% of 0.1-5 mM uranium was reduced. However, reduction in killed-control cultures suggests either a strong potential for abiotic reduction or the ability to form spores. Thus, the potential for uranium reduction was observed, but further research is necessary to determine which environmental parameters are controlling uranium transformation by this organism.
Show less
Date Issued: 2005
Identifier: FSU_migr_etd-0599
Format: Thesis

Title: Development of New Techniques for Assimilating Satellite Altimetry Data into Ocean Models.
Creator: Yu, Peng, O'Brien, James J., Zou, Xiaolei, Dewar, William K., Clarke, Allan J., Iverson, Richard, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: State of the art fully three-dimensional ocean models are very computationally expensive and their adjoints are even more resource intensive. However, many features of interest are approximated by the first baroclinic mode over much of the ocean, especially in the lower and mid latitude regions. Based on this dynamical feature, a new type of data assimilation scheme to assimilate sea surface height (SSH) data, a reduced-space adjoint technique, is developed and implemented with a three...
Show moreState of the art fully three-dimensional ocean models are very computationally expensive and their adjoints are even more resource intensive. However, many features of interest are approximated by the first baroclinic mode over much of the ocean, especially in the lower and mid latitude regions. Based on this dynamical feature, a new type of data assimilation scheme to assimilate sea surface height (SSH) data, a reduced-space adjoint technique, is developed and implemented with a three-dimensional model using vertical normal mode decomposition. The technique is tested with the Navy Coastal Ocean Model (NCOM) configured to simulate the Gulf of Mexico. The assimilation procedure works by minimizing the cost function, which generalizes the misfit between the observations and their counterpart model variables. The "forward" model is integrated for the period during which the data are assimilated. Vertical normal mode decomposition retrieves the first baroclinic mode, and the data misfit between the model outputs and observations is calculated. Adjoint equations based on a one-active-layer reduced gravity model, which approximates the first baroclinic mode, are integrated backward in time to get the gradient of the cost function with respect to the control variables (velocity and SSH of the first baroclinic mode). The gradient is input to an optimization algorithm (the limited memory Broyden-Fletcher-Goldfarb-Shanno (BFGS) method is used for the cases presented here) to determine the new first baroclinic mode velocity and SSH fields, which are used to update the forward model variables at the initial time. Two main issues in the area of ocean data assimilation are addressed: 1. How can information provided only at the sea surface be transferred dynamically into deep layers? 2. How can information provided only locally, in limited oceanic regions, be horizontally transferred to ocean areas far away from the data-dense regions, but dynamically connected to it? The first problem is solved by the use of vertical normal mode decomposition, through which the vertical dependence of model variables is obtained. Analyses show that the first baroclinic mode SSH represents the full SSH field very closely in the model test domain, with a correlation of 93% in one of the experiments. One common way to solve the second issue is to lengthen the assimilation window in order to allow the dynamic model to propagate information to the data-sparse regions. However, this dramatically increases the computational cost, since many oceanic features move very slowly. An alternative solution to this is developed using a mapping method based on complex empirical orthogonal functions (EOF), which utilizes data from a much longer period than the assimilation cycle and deals with the information in space and time simultaneously. This method is applied to map satellite altimeter data from the ground track observation locations and times onto a regular spatial and temporal grid. Three different experiments are designed for testing the assimilation technique: two experiments assimilate SSH data produced from a model run to evaluate the method, and in the last experiment the technique is applied to TOPEX/Poseidon and Jason-1 altimeter data. The assimilation procedure converges in all experiments and reduces the error in the model fields. Since the adjoint, or "backward", model is two-dimensional, the method is much more computationally efficient than if it were to use a fully three-dimensional backward model.
Show less
Date Issued: 2006
Identifier: FSU_migr_etd-0789
Format: Thesis

Title: Using Chemical Tracers to Evaluate Feeding Habits in Coastal Marine Ecosystems: Stable Isotopes and Organic Contaminants.
Creator: Wilson, Rachel Marie, Chanton, Jeffrey P., Cooper, William T., Nowacek, Douglas P., Kucklick, John R., Wang, Yang, Burnett, William C., Department of Earth, Ocean and...
Show moreWilson, Rachel Marie, Chanton, Jeffrey P., Cooper, William T., Nowacek, Douglas P., Kucklick, John R., Wang, Yang, Burnett, William C., Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Show less
Abstract/Description: The use of chemical tracers to understand ecosystem interactions in the marine environment has gained increasing popularity over the past three decades. Carbon isotope abundances in organic matter sources in the marine system vary significantly making them a useful tracer for discriminating among such sources. Once taken up by primary producers, carbon isotope abundances are conservative throughout the food web. This allows us to measure carbon isotope abundances in secondary (and above)...
Show moreThe use of chemical tracers to understand ecosystem interactions in the marine environment has gained increasing popularity over the past three decades. Carbon isotope abundances in organic matter sources in the marine system vary significantly making them a useful tracer for discriminating among such sources. Once taken up by primary producers, carbon isotope abundances are conservative throughout the food web. This allows us to measure carbon isotope abundances in secondary (and above) consumers and infer organic matter source utilization in the system. Nitrogen isotope abundances, unlike carbon, are not conservative throughout the food web. However, they do fractionate predictably providing a tool by which to measure trophic level of consumer species. Sulfur isotopes, like carbon, differ among sources and are also conservative within the food web providing an additional tracer with which to estimate source contributions. However, concerns about the "dirtiness" of sulfur for analysis purposes put sulfur on the back burner as an ecosystem tracer. With recent improvements in technology and the need for multiple tracers in multi-source systems, sulfur isotope abundance measurements have experienced a resurgence. In this manuscript we use sulfur isotope abundances as a second tracer (with carbon isotope abundances) to estimate organic matter source utilization by consumers in a variety of habitats along the Florida Big Bend coastline. We begin our isotopic analysis of consumers in a Northwest Gulf of Mexico, freshwater dominated estuarine system, Apalachicola Bay, Florida (USA). In Chapter II we evaluate isotopic variation with body size to determine the smallest trophic unit in our system. In Chapter III we develop a concentration-corrected, dual-isotope, multi-source evaluation of organic matter utilization incorporating sulfur as a secondary tracer. We then go on to apply the results of this model to determine trophic level of consumers in Apalachicola Bay based on nitrogen isotope abundance data. In Chapter IV we demonstrate how isotopic variation of sources within a system can confound our interpretations of trophic structure using these methods. We further demonstrate that, in addition to isotopic variation, source inputs and availability may also vary within a given system. This makes comparison among sites more difficult and highlights the need to evaluate isotopic variation in individual systems prior to making comparisons or widespread generalizations about interactions. In Chapter V we apply these methods to a coastal seagrass community. We evaluate isotopic abundances in sources in consumers from the site. Then we apply the mixing model we develop in Chapter II to determine organic matter source utilization by consumers. Finally, we evaluate trophic level of individual consumers and trophic structure of the system based on nitrogen isotopic abundances. We demonstrate that source isotopic abundances differ from those same sources in the freshwater estuarine habitats. We also show that, while benthic organic matter was an important source in Apalachicola Bay, epiphytes provide the major organic matter source supporting consumers in the seagrass habitat. We use source utilization information and trophic level to assign consumers to trophic guilds in this system. The variety of organic matter source utilization is thought to contribute to the high levels of productivity found in this region. In addition to natural tracers, such as isotope abundances, we have also used organic pollutants as tracers of habitat utilization in the Florida Big Bend region. Organic contaminants found in coastal waters include compounds such as DDTs, PCBs, and chlordanes. Although no longer produced in the U.S., their historically wide-spread use and resistance to degradation contributes to their persistence in marine biota. We present data on chemical concentrations and congener profiles in bottlenose dolphins (Tursiops truncatus) and two abundant fish species from this region in Chapter VI. Although this area has been called "pristine" by previous researchers, we demonstrate the relativeness of this term, revealing that even the "forgotten coast" has been influenced by these ubiquitous contaminants. We use these compounds as tracers to evaluate bottlenose dolphin habitat utilization patterns in Florida Big Bend coastal waters. We found that the dolphins we sampled have differences in concentrations and patterns of contaminant loading indicating preference for feeding in specific areas and bays. Our results agree with suggestions based on sighting information that animals from the east and west regions of our study site rarely comingle and that even in the western site, individual animals express preferences for either St Joseph or St Andrews Bay foraging grounds.
Show less
Date Issued: 2010
Identifier: FSU_migr_etd-0901
Format: Thesis

Title: The Role of Equatorial Pacific Currents in El Nino and El Nino Prediction.
Creator: Zhang, Xiaolin, Clarke, Allan J., Tam, Christopher K. W., Bourassa, Mark Allan, Dewar, William K., Landing, William M., Florida State University, College of Arts and Sciences,...
Show moreZhang, Xiaolin, Clarke, Allan J., Tam, Christopher K. W., Bourassa, Mark Allan, Dewar, William K., Landing, William M., Florida State University, College of Arts and Sciences, Department of Earth, Ocean, and Atmospheric Science
Show less
Abstract/Description: Fundamental to an understanding of El Niño/Southern Oscillation climate fluctuations is an understanding of the interannual equatorial Pacific surface flows, which advect the surface waters and change the sea surface temperature. While some knowledge of the observed interannual flows has already been obtained, some key features are still not fully understood. Using the long records of satellite altimeter data, together with long in situ records of current, salinity and temperature from the...
Show moreFundamental to an understanding of El Niño/Southern Oscillation climate fluctuations is an understanding of the interannual equatorial Pacific surface flows, which advect the surface waters and change the sea surface temperature. While some knowledge of the observed interannual flows has already been obtained, some key features are still not fully understood. Using the long records of satellite altimeter data, together with long in situ records of current, salinity and temperature from the TAO/TRITON array in the equatorial Pacific, the observed interannual surface flows, their dynamics and link to the El Niño Prediction can be understood better. In the first half of the thesis, I used theoretical arguments and a wind-forced ocean model to understand why the equatorial eastern Pacific flow leads sea level, eastern equatorial thermocline displacement and El Niño indices. This half of the thesis is based on the result that for large zonal scales and low frequencies, wind-forced sea level, even near the equator, can be described by wind-forced long Rossby waves. In the eastern equatorial Pacific where the interannual wind forcing is small, these waves are essentially locally unforced and propagate westward from the boundary. At the boundary the wave’s sea level is in phase because of geostrophy and no normal flow to the boundary. However, because the waves propagate more slowly with increasing latitude, west of the boundary lag increases as latitude increases. Consequently a northward sea level gradient is like a time derivative, and the zonal geostrophic flow is like a time derivative of the sea level. This implies that the equatorial flow should lead the equatorial sea level by about 9 months on El Niño time scales. Analysis shows that when dissipation of the large-scale flow is taken into account, this lead is reduced to about 3 months. This lead time is approximately the dissipation time scale of the second vertical mode, which dominates the zonal surface flow. Since the eastern equatorial Pacific sea level is proportional to eastern equatorial thermocline displacement and El Niño, the zonal equatorial flow leads El Niño indices. Analysis further shows that the zonally-averaged equatorial Pacific sea level leads El Niño, and that this lead is associated with the geostrophic zonal velocity and the long Rossby wave physics in the eastern equatorial Pacific. The second part of this work addresses the influence of the heavy precipitation on the Western equatorial Pacific Ocean. Surface and subsurface salinity and temperature measurements at 137oE, 147oE, and 156oE since the late 1990s from the western equatorial Pacific TRITON moored array indicate that the large interannual sea surface salinity (SSS) fluctuations there change little with depth over the top 50 m of the water column. Beneath this surface layer the SSS signal decreases, and is usually much smaller at about 100 m depth. The isothermal layer depth (ILD) ranges from about 50–70 m and estimates of dynamic height relative to the ILD indicate a near-surface salinity-driven contribution to the monthly sea level anomaly that is uncorrelated with, and smaller than, interannual sea surface height (SSH) estimated from altimeter data. Despite the smaller size of , its meridional gradient dominates the total sea level meridional gradient and thus the corresponding shallow equatorially-trapped interannual fresh water jet dominates the near-surface zonal interannual flow. This jet-like flow has a meridional scale of only about 2–3o of latitude, an amplitude of 23cm/s, and is associated with the zonal back and forth displacement of the western equatorial warm/fresh pool that is fundamental to El Niño. The jet is not forced by the interannual fresh water surface flux but rather by wind stress anomalies that are mostly east of the warm/fresh pool edge during La Niña and mostly west of it during El Niño.
Show less
Date Issued: 2017
Identifier: FSU_SUMMER2017_Zhang_fsu_0071E_13691
Format: Thesis

Title: The Influence of Atmospheric Cold Air Outbreaks on the Upper Ocean Thermal Variability of the Florida Straits.
Creator: Rudzin, Johna, Earth, Ocean & Atmospheric Science
Abstract/Description: The purpose of this study is to investigate the impacts of cold air outbreaks (CAOs) on the sea surface temperature (SST) in the Florida Straits (FS) during different configurations (mature or immature) of the Loop Current (LC). A satellite-derived SST data set is used to calculate the difference in SST anomalies between the FS and the Yucatan Channel (YC). The SST anomaly time series is analyzed during the winter season for times of mature and immature LC configurations determined from a...
Show moreThe purpose of this study is to investigate the impacts of cold air outbreaks (CAOs) on the sea surface temperature (SST) in the Florida Straits (FS) during different configurations (mature or immature) of the Loop Current (LC). A satellite-derived SST data set is used to calculate the difference in SST anomalies between the FS and the Yucatan Channel (YC). The SST anomaly time series is analyzed during the winter season for times of mature and immature LC configurations determined from a satellite altimetry-derived time series of LC position. This analysis shows a greater likelihood of anomalous cooling of SSTs in the FS compared to the SSTs in the YC during times of an extended, or mature, LC. This result leads to the hypothesis that surface water is subject to greater cooling during a mature LC (due to the greater residence time of the water under cold air masses) than an immature LC, and this cooler water is advected into the FS. This hypothesis is investigated by computing an approximate heat budget for the Yucatan-Loop-Florida Current (YLFC) under identical atmospheric forcing using twin ocean model simulations with mature and immature LC configurations.
Show less
Date Issued: 2012
Identifier: FSU_migr_uhm-0056
Format: Thesis

Title: Multi-Decadal Variations of Durations of Extreme Temperatures in the Southeastern United States.
Creator: Worsnop, Rochelle, Earth, Ocean & Atmospheric Science
Abstract/Description: The number of extreme temperature occurrences and their durations in the southeast United States varies during three periods: the Warm Regime subset (WRs), the Cold Regime subset (CRs), and the Modern Record (MR). Multidecadal variations in the regional patterns of the counts and durations of summer-day and winter-day extremes reveal that during the MR, the extreme temperature counts and durations in Florida are more consistent with a WRs setup whereas these parameters for the inland states ...
Show moreThe number of extreme temperature occurrences and their durations in the southeast United States varies during three periods: the Warm Regime subset (WRs), the Cold Regime subset (CRs), and the Modern Record (MR). Multidecadal variations in the regional patterns of the counts and durations of summer-day and winter-day extremes reveal that during the MR, the extreme temperature counts and durations in Florida are more consistent with a WRs setup whereas these parameters for the inland states (Alabama, Georgia, North Carolina, and South Carolina) are more consistent with a CRs setup. We also found that during the CRs (WRs), the majority of stations show a statistically significant increase in the likelihood of exactly one winter-day (summer-day) extreme occurrence. During the MR, both inland and coastal stations show a statistically significant increase in the likelihood of exactly one winter-day occurrence. This increased likelihood is not seen during the MR for a summer-day extreme occurrence. Patterns in the behavior of summer-day and winter-day extremes during the CRs and WRs may provide insight about how extreme temperatures will behave in future periods, if the period is forecasted to have similar setups to that of the CRs or WRs. Insight about the duration and counts of extreme temperatures is useful to the agricultural community, power industries, and health officials.
Show less
Date Issued: 2012
Identifier: FSU_migr_uhm-0050
Format: Thesis

Title: A Case Study of 2010 Hurricane Karl to Evaluate the Precipitation Forecasts of the Post Updated 2010 Global Ensemble Forecast System.
Creator: Day, Lindsey, Earth, Ocean & Atmospheric Science
Abstract/Description: This research project seeks to evaluate the rainfall forecast accuracy of the GEFS (Global Ensemble Forecast System) following the 2010 model update, analyzing the Atlantic September 2010 Hurricane Karl as a case study. Archived forecasted accumulated precipitation amounts from the GEFS are compared with archived CMORPH (CPC Morphing Technique) precipitation estimates. A sequence of 15 six hour forecasts from 1200 UTC 14 September 2010 to 1200 UTC 18 September 2010 are graphically displayed...
Show moreThis research project seeks to evaluate the rainfall forecast accuracy of the GEFS (Global Ensemble Forecast System) following the 2010 model update, analyzing the Atlantic September 2010 Hurricane Karl as a case study. Archived forecasted accumulated precipitation amounts from the GEFS are compared with archived CMORPH (CPC Morphing Technique) precipitation estimates. A sequence of 15 six hour forecasts from 1200 UTC 14 September 2010 to 1200 UTC 18 September 2010 are graphically displayed using GrADS (Grid Analysis and Display System). Four images were produced for each of the 15 six-hour time frames: A) CMORPH 6-hour accumulated precipitation, B) GEFS 6-hour accumulated precipitation, C) Difference in GEFS and CMORPH 6-hour accumulated precipitation (GEFS-CMORPH), and D) Overlay of outlined areas of medium (≥0.25 inches) and heavy (≥1.0 inches) precipitation for the GEFS and CMORPH. Several errors in the precipitation forecast of the GEFS model post-update were consistent with errors found in the GEFS model prior to its 2010 update from previous studies. For example, the GEFS forecasted the size of the hurricane to be too large for all evaluated times. Although the six hour GEFS track forecast was closely aligned with that of the verified track, major differences between the forecast and verification occurred as the storm approached its second landfall in Mexico. This study highlights that although the model may accurately depict the storm track, other model biases such as a lower resolution, difficulty depicting the atmosphere near land/sea boundaries and over complex terrain—may significantly impact the precipitation forecast.
Show less
Date Issued: 2011
Identifier: FSU_migr_uhm-0011
Format: Thesis

Title: A Case Study of a Hybrid Cyclone: 6-9 September 2009.
Creator: Sliwinski, Timothy, Earth, Ocean & Atmospheric Science
Abstract/Description: Hybrid cyclones, such as subtropical storms and warm seclusions, are generally defined by the fact that they contain characteristics of the main types of cyclones: tropical and extratropical. This case study examines whether a cyclone can be considered hybrid without experiencing a transition from either of these two main types. The case in question occurred between 6 and 9 September 2009 before becoming frontal. The cyclone formed independently of other cyclones and was shallow warm-core at...
Show moreHybrid cyclones, such as subtropical storms and warm seclusions, are generally defined by the fact that they contain characteristics of the main types of cyclones: tropical and extratropical. This case study examines whether a cyclone can be considered hybrid without experiencing a transition from either of these two main types. The case in question occurred between 6 and 9 September 2009 before becoming frontal. The cyclone formed independently of other cyclones and was shallow warm-core at its start. It would go on to exhibit properties of tropical cyclones such as a stacked surface warm-core and even convection occurring at the center. It would also go on to exhibit properties of extratropical cyclones by strengthening whenever an upper-level shortwave came near, increasing baroclinicity. This study looks at the large-scale patterns of development and utilizes the diagnostic properties of the terms of the quasi-geostrophic omega equation to understand the forcings in the area of the cyclone as depicted in the North American Regional Reanalysis. In addition, cyclone phase diagrams were generated for other analyses to determine whether the characteristics depict hybrid, extratropical, tropical, or subtropical development based on the parameters of thermal wind and thermal symmetry. It was found that the system was a hybrid system in that a warm-core surface cyclone did exist from the surface to 500 hPa; however upper-level short waves about an upper-level trough were responsible for providing forcing for the genesis and strengthening of this storm.
Show less
Date Issued: 2011
Identifier: FSU_migr_uhm-0038
Format: Thesis

Title: Determinig the Effects of Stokes Drift on the Movement of Oil in the Gulf of Mexico.
Creator: Heath, Nicolas, Earth, Ocean & Atmospheric Science
Abstract/Description: The impact of Stokes drift, a wave-driven mechanism of mass transport, is investigated for surface oil movement in the Gulf of Mexico. Stokes drift was neglected in trajectory forecasts in the Gulf during the Deepwater Horizon oil spill. The key considerations used in Gulf of Mexico trajectory forecasts were surface currents and wind drift. This study presents a physical argument for the importance of Stokes drift and questions the significance of wind drift over an oil slick. Furthermore,...
Show moreThe impact of Stokes drift, a wave-driven mechanism of mass transport, is investigated for surface oil movement in the Gulf of Mexico. Stokes drift was neglected in trajectory forecasts in the Gulf during the Deepwater Horizon oil spill. The key considerations used in Gulf of Mexico trajectory forecasts were surface currents and wind drift. This study presents a physical argument for the importance of Stokes drift and questions the significance of wind drift over an oil slick. Furthermore, the magnitude and direction of the wind drift (2–5% of the wind speed and 20° to the right in the Northern Hemisphere) is very similar to that of the Stokes drift. For this reason, the differences between Stokes drift and the wind drift are examined using a vector comparison. The directional components of Stokes drift and the wind drift are found to be very similar although the magnitudes of the wind drift are found to be larger. When swell not associated with the local wind is present, however, the two drifts have significantly different directional components. Horizontal surface trajectories are computed for different atmospheric and oceanic conditions. Trajectory results are compared to satellite-derived oil locations using a center of mass comparison method. Analysis of trajectory forecasts and observed oil locations suggests that Stokes drift might play an important role in the movement of oil at the surface and that the magnitude of the wind drift may not be as large as most models presume. Key
Show less
Date Issued: 2011
Identifier: FSU_migr_uhm-0017
Format: Thesis

Title: Analysis of GFDL Intensity Forecasting Performance for Gulf/Caribbean Major Hurricanes from 1998-2008.
Creator: Hazelton, Andrew, Earth, Ocean & Atmospheric Science
Abstract/Description: While both computer model and official track forecasts of Atlantic Basin hurricanes have improved significantly over the past several decades, forecasts of intensity continue to prove difficult. Even specialized hurricane models struggle with predicting intensity. This study analyzes the intensity errors of the Geophysical Fluid Dynamics Laboratory (GFDL) Hurricane Model for 19 major hurricanes over the Gulf of Mexico and Caribbean Sea from 1998 to 2008. Using the measure of skill relative to...
Show moreWhile both computer model and official track forecasts of Atlantic Basin hurricanes have improved significantly over the past several decades, forecasts of intensity continue to prove difficult. Even specialized hurricane models struggle with predicting intensity. This study analyzes the intensity errors of the Geophysical Fluid Dynamics Laboratory (GFDL) Hurricane Model for 19 major hurricanes over the Gulf of Mexico and Caribbean Sea from 1998 to 2008. Using the measure of skill relative to the Statistical Hurricane Intensity Forecast (SHIFOR), the GFDL forecasts generally improved throughout most of the 11-year period, although there were some exceptions to this increase in skill. Comparing the GFDL to the Statistical Hurricane Intensity Prediction Scheme (SHIPS), it is found that the GFDL was slightly outperformed by SHIPS on most of the forecast categories and times. It seems that there is a correlation between higher intensity storms and higher errors (R = 0.53), and there is also a clear relationship between large negative errors and rapid intensification (R = 0.62). This relationship is explored for some of the ―higher-error‖ cases by comparing the GFDL forecast intensity progression with the actual intensity change. Hurricanes Dean (2007) and Felix (2007) are also analyzed in more detail, since both of these storms were exceptions to the general trend in increased skill from 2000-2008. It is hoped that this and further analysis will illuminate reasons for the model's difficulty with the intensity forecasts, and provide a basis for improving model forecasts and official forecasts of tropical cyclone intensity.
Show less
Date Issued: 2011
Identifier: FSU_migr_uhm-0014
Format: Thesis

Title: Separation and Characterization of Copper Binding Ligands in Dissolved Organic Matter in Lake Bradford.
Creator: Prugue, Rodrigo, Earth, Ocean & Atmospheric Science
Abstract/Description: Trace metals are important compounds in aquatic environments. In low concentrations, they can be very beneficial to aquatic life. However, they can be toxic if present in moderate to high concentrations. A growing interest has occurred involving ligands. Trace metals like copper are most commonly found complexed with ligands in fresh and marine waters. Many organisms also produce compounds to help mitigate increases in dissolved copper and prevent toxic environments. However, very little is...
Show moreTrace metals are important compounds in aquatic environments. In low concentrations, they can be very beneficial to aquatic life. However, they can be toxic if present in moderate to high concentrations. A growing interest has occurred involving ligands. Trace metals like copper are most commonly found complexed with ligands in fresh and marine waters. Many organisms also produce compounds to help mitigate increases in dissolved copper and prevent toxic environments. However, very little is known on how these ligands behave and what causes them to complex with trace metals. This project aims to separate and characterize copper binding ligands from a local lake in Tallahassee, FL. The motivation is to improve understanding of this complex process and mitigate future environmental issues dealing with elevated issues of metals in aquatic environments. UV/Vis spectrometry data did not yield any conclusive results since the peaks seen were very similar to what copper and the chelating agent used, EDTA, looked like. However, the data produced by the electrospray ionization mass spectrometer does indicate the presence of specific compounds which were affected by the pH of the solution. Although the data did not yield any characteristic data, we concluded that the IMAC process is capable of fractionating copper binding ligands.
Show less
Date Issued: 2012
Identifier: FSU_migr_uhm-0064
Format: Thesis

Title: An Analysis of the Extratropical Flow Response to Recurving Atlantic Tropical Cyclones.
Creator: Brannan, Allison, Department of Earth, Ocean and Atmospheric Sciences
Abstract/Description: There is a significant frequency of Atlantic tropical cyclones that complete extratropical transition and recurve in the mid-latitudes. Using a climatological approach, this study will analyze the extratropical flow response to recurving Atlantic tropical cyclones and compare the results to those from the Western North Pacific, as examined by Archambault et al. (2013). This investigation includes 54 recurving Atlantic tropical cyclones occurring between 2007 and 2013. The extratropical flow...
Show moreThere is a significant frequency of Atlantic tropical cyclones that complete extratropical transition and recurve in the mid-latitudes. Using a climatological approach, this study will analyze the extratropical flow response to recurving Atlantic tropical cyclones and compare the results to those from the Western North Pacific, as examined by Archambault et al. (2013). This investigation includes 54 recurving Atlantic tropical cyclones occurring between 2007 and 2013. The extratropical flow response will be quantified using potential vorticity. Characteristics of tropical cyclones, the extratropical jet stream, and the dynamical "phasing" of their interaction will be examined to determine the features that lead to significantly amplified extratropical flow. Results show the extratropical flow to be insensitive to the wind speed, latitude, and month of recurvature. However, there is an association between low mean sea level pressure and a larger amplification of flow. Finally, tropical cyclones recurving on the east side of the nearest trough are shown to have "favorable phasing," which yields amplification of the extratropical flow.
Show less
Date Issued: 2015
Identifier: FSU_migr_uhm-0538
Format: Thesis

Title: Hurricane Sandy and New Jersey: The Nature of a Natural Disaster.
Creator: Blaskiewicz, Claire S., Department of Earth, Ocean and Atmospheric Sciences
Abstract/Description: While natural disasters can often be catalysts for change, understanding where to begin changing can be discovered by looking at the science and history of the affected area. Hurricane Sandy's unprecedented landfall in October 2012 began this progression for the state of New Jersey. This study examines the processes affecting the ocean and beaches of New Jersey, looks at the effects of Hurricane Sandy on the state and discusses the changing standards that have been and continue to be enacted...
Show moreWhile natural disasters can often be catalysts for change, understanding where to begin changing can be discovered by looking at the science and history of the affected area. Hurricane Sandy's unprecedented landfall in October 2012 began this progression for the state of New Jersey. This study examines the processes affecting the ocean and beaches of New Jersey, looks at the effects of Hurricane Sandy on the state and discusses the changing standards that have been and continue to be enacted since storm recovery began. Specifically highlighted are the engineering practices of flood mitigation, the effects of the storm on the state's economy and the new policies and standards that have come about in the aftermath.
Show less
Date Issued: 2014
Identifier: FSU_migr_uhm-0564
Format: Thesis

Title: Circulation in the Lau Basin and Havre Trough.
Creator: Simons, Elizabeth G. (Elizabeth Gabrielle), Speer, Kevin G., Cogan, Nicholas G., Dewar, William K., Sura, Philip, Florida State University, College of Arts and Sciences, Program...
Show moreSimons, Elizabeth G. (Elizabeth Gabrielle), Speer, Kevin G., Cogan, Nicholas G., Dewar, William K., Sura, Philip, Florida State University, College of Arts and Sciences, Program in Geophysical Fluid Dynamics
Show less
Abstract/Description: The ridge systems that frame the Lau Basin and Havre Trough, located east of Fiji and north of New Zealand, separating a large counterclockwise gyre at the surface into two smaller gyres at depth. A strong deep western boundary current (DWBC) has been observed flowing northward, following the Tonga and Kermadec Trench systems, transporting bottom water to the North Pacific. Though circulation has been described to some degree around the Lau Basin and the Havre Trough, these sub-basins have...
Show moreThe ridge systems that frame the Lau Basin and Havre Trough, located east of Fiji and north of New Zealand, separating a large counterclockwise gyre at the surface into two smaller gyres at depth. A strong deep western boundary current (DWBC) has been observed flowing northward, following the Tonga and Kermadec Trench systems, transporting bottom water to the North Pacific. Though circulation has been described to some degree around the Lau Basin and the Havre Trough, these sub-basins have largely been ignored, presumed to act as a barrier to flow and separating the western South Pacific from the eastern South Pacific. An analysis of float data from several sources as well as traditional ship-board hydrographic data reveal a DWBC within the Lau Basin and Havre Trough that is fed by westward flowing jets from breaks within the ridge system. A simple analytical model predicts the large-scale dynamics observed in the basin, and indicates that the topographic structure of the ridge modulates the flow patterns. Sources of water into the Lau Basin and Havre Trough indicate intermediate water sources from the eastern South Pacific, while deep water sources originate to the west. This leads to a revised view of the role of the Lau Basin and Havre Trough with respect to circulation in the South Pacific.
Show less
Date Issued: 2018
Identifier: 2018_Sp_Simons_fsu_0071E_14508
Format: Thesis

Title: A quantitative comparison of meiofaunal distributions in an open sand area and a sea grass bed (Thalassia testudinum).
Creator: Ruddell, John Milton
Date Issued: 1976
Identifier: FSU_QL121R8
Format: Thesis

Title: The Origin of the North Atlantic Clod Blob Revisited.
Creator: Bhatrasataponkul, Tachanat, Bourassa, Mark Allan, Elsner, James B., Clarke, Allan J., Dewar, William K., Speer, Kevin G., Florida State University, College of Arts and Sciences,...
Show moreBhatrasataponkul, Tachanat, Bourassa, Mark Allan, Elsner, James B., Clarke, Allan J., Dewar, William K., Speer, Kevin G., Florida State University, College of Arts and Sciences, Department of Earth, Ocean and Atmospheric Science
Show less
Abstract/Description: The cold blob refers to an observationally unprecedented, gyre-scale, record-breaking cold of mean surface temperature over the subpolar North Atlantic. Its anomalous cold feature goes against the rising trend of global mean surface temperature in the context of a warming climate. Observations show that the Atlantic cold blob emerged in early 2014 and can penetrate deeper into the ocean interior beyond 500m depths. A sudden drop in upper ocean heat content is associated with an accumulative...
Show moreThe cold blob refers to an observationally unprecedented, gyre-scale, record-breaking cold of mean surface temperature over the subpolar North Atlantic. Its anomalous cold feature goes against the rising trend of global mean surface temperature in the context of a warming climate. Observations show that the Atlantic cold blob emerged in early 2014 and can penetrate deeper into the ocean interior beyond 500m depths. A sudden drop in upper ocean heat content is associated with an accumulative increase in freshwater content. Prior works pointed out that intense surface forcing during two consecutive winters was a primary driver. We hypothesize that surface forcing alone is insufficient for the cold blob to persist. Our analysis shows, for the first time, that variations in the net surface heat fluxes cannot explain the decline in upper ocean heat content during 2014–2017. Therefore, surface forcing fails to explain the origin of the cold blob. To investigate alternative mechanisms, non-assimilative simulations based on a coupled ocean-sea ice model (GFDL MOM5/SIS1) with two different atmospheric forcings (MERRA2 and ERA-interim) are employed to examine the transports of mass, heat, and freshwater within the cold blob area. Initial diagnosis verified that both model runs can reproduce the cold blob characteristics at similar magnitudes to Argo observations. Model results show a decreasing trend of heat transport at the southern boundary, implying that reduced poleward ocean heat transport likely accounts for the formation and persistence of the cold blob. This cooling signal from the south is accompanied by a freshening signal. Changes in the residual heat fluxes suggest that reduced warming for the subsurface layer at 100–700 m depths apparently occurred since 2006 before turning into enhanced cooling during late 2013. Variations in the residual freshwater fluxes remain positive for the entire past decade and subsequently result in an accumulative surplus of freshwater content in this area. The model run with incorporated Greenland meltwater estimates sheds light on the relative contribution of meltwater advection. To a great extent, Greenland meltwater can amplify the freshening tendency in the subpolar North Atlantic by approximately up to 200% during the present decade. In the long run, upper ocean cooling and freshening would lead to increased stratification and reduced mixing with deeper waters, therefore enhancing the likelihood that the subsurface cold blob persists.
Show less
Date Issued: 2018
Identifier: 2018_Fall_Bhatrasataponkul_fsu_0071E_14875
Format: Thesis

Title: Two-Way Feedback between Air-Sea Turbulent Fluxes and Oceanic Submesoscale Processes.
Creator: Chen, Xu, Dewar, William K., Chassignet, Eric P., Tam, Christopher K. W., Bourassa, Mark Allan, Morey, Steven L., Florida State University, College of Arts and Sciences,...
Show moreChen, Xu, Dewar, William K., Chassignet, Eric P., Tam, Christopher K. W., Bourassa, Mark Allan, Morey, Steven L., Florida State University, College of Arts and Sciences, Department of Earth, Ocean and Atmospheric Science
Show less
Abstract/Description: An accurate representation of air-sea interaction is crucial to the accurate numerical prediction of ocean, weather, and climate. It is known that sea surface temperature (SST) gradients and surface currents in the oceanic mesoscale regime significantly affect air-sea fluxes of momentum and heat, and the mesoscale-modified air-sea fluxes also influence the ocean dynamics on various scales. Previous studies found that resolving the mutual feedbacks between mesoscale processes and the...
Show moreAn accurate representation of air-sea interaction is crucial to the accurate numerical prediction of ocean, weather, and climate. It is known that sea surface temperature (SST) gradients and surface currents in the oceanic mesoscale regime significantly affect air-sea fluxes of momentum and heat, and the mesoscale-modified air-sea fluxes also influence the ocean dynamics on various scales. Previous studies found that resolving the mutual feedbacks between mesoscale processes and the atmosphere improved the accuracy of modeling for ocean, weather, and climate. In the submesoscale regime recently revealed by high-resolution numerical models and observations, the SST gradient and surface currents are found to be much stronger than those in the mesoscale. However, the mutual feedbacks between the submesoscale processes and the atmosphere are not well understood. To quantitatively assess the mutual responses between the air-sea fluxes and the submesoscale processes, a non-hydrostatic ocean model coupled with an atmospheric boundary layer module is implemented making it possible to examine the air-sea interactions over submesoscale regime. We here argue that the inclusion of surface currents in air-sea bulk flux parameterization and the atmospheric thermodynamic adjustments to the ocean surface are determined to be significant for modeling accurate wind stress and air-sea turbulent heat fluxes in the submesoscale regime. The results show that the linear relationship between wind stress curl/divergence and crosswind/downwind SST gradient, revealed in the mesoscale regime, do not exist in the submesoscale regime. Additionally, the magnitudes of positive and negative wind stress curl introduced by submesoscale processes are much greater than the magnitude of wind stress curl introduced by mesoscale processes. This study also finds that the evolution of submesoscale processes is closely associated with the potential vorticity (PV) budget. Because different fields of wind stress and turbulent heat fluxes are introduced by the influence of submesoscale surface velocity field and/or temperature field, these wind stress and heat flux fields can interact with submesoscale surface structures and provide different PV injections into the ocean. Therefore, the evolution of submesoscale processes is significantly influenced by the submesoscale-modified air-sea fluxes. This study serves as a starting point in the investigation of the two-way feedback between the atmosphere and oceanic submesoscale processes. It shows that numerically resolving the two-way air-sea coupling in the submesoscale regime significantly changes air-sea flux and the oceanic submesoscale dynamics.
Show less
Date Issued: 2018
Identifier: 2018_Fall_Chen_fsu_0071E_14913
Format: Thesis

Title: Source Driven Rotating Flow in a Basin with Topography.
Creator: Vijayan Nair Rugminiamma, Linoj, Speer, Kevin G. (Kevin George), Tam, Christopher K. W., Dewar, William K., Florida State University, College of Arts and Sciences, Department of...
Show moreVijayan Nair Rugminiamma, Linoj, Speer, Kevin G. (Kevin George), Tam, Christopher K. W., Dewar, William K., Florida State University, College of Arts and Sciences, Department of Earth, Ocean and Atmospheric Science
Show less
Abstract/Description: Laboratory experiments on a rotating tank of fluid are used to study the fundamental aspects of geophysical fluid flows. The present set of experiments are an attempt to study the effect of a rectangular ridge on the flow of a rotating fluid confined by lateral boundaries and forced by a source. First dye and later Particle Image Velocimetry (PIV) are used to understand the circulation in the domain. A strong southern boundary flow near the western wall of the domain and a cyclonic...
Show moreLaboratory experiments on a rotating tank of fluid are used to study the fundamental aspects of geophysical fluid flows. The present set of experiments are an attempt to study the effect of a rectangular ridge on the flow of a rotating fluid confined by lateral boundaries and forced by a source. First dye and later Particle Image Velocimetry (PIV) are used to understand the circulation in the domain. A strong southern boundary flow near the western wall of the domain and a cyclonic circulation in the trench are observed in these experiments. Overflow from the eastern side to the west of the ridge is seen along the N-S length of the ridge, though the overflow is pronounced near the northern boundary of the domain. Simplified mathematical models are used to describe the observed circulation. Numerical simulations are conducted using the MIT general circulation model on a large scale idealized box domain with a topography similar to the one we used in the laboratory tank as well as a rectangular trench parallel to the eastern wall of the domain. A point mass source contributes to the upwelling at the free surface. This set up represents a homogeneous abyssal layer upwelling slowly due to a polar source. Results indicate a cyclonic sense of circulation and a poleward eastern boundary current over the ridge wall. This intensification can be attributed to the vortex stretching over the slopes of the ridge, as the vertical walls appear in the numerical model as having a steep slope. Friction on vertical walls of the ridge are also a cause of this intensification. Some features of the observed and modeled circulation are compared to the oceanic flow in the deep Pacific Ocean.
Show less
Date Issued: 2019
Identifier: 2019_Spring_VijayanNairRugminiamma_fsu_0071N_15039
Format: Thesis

Title: Impact of Airborne Dust on Sea Surface Temperature Retrievals.
Creator: Bogdanoff, Alec Setnor, Clayson, Carol Anne, Bourassa, Mark A., Liu, Guosheng, Westphal, Douglas L., Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Sea Surface Temperatures (SSTs) are an important measure of our current weather and climate, as well as an essential variable in both short and long term weather forecasting. Infrared SST retrievals are reliant on passive sensors, and retrieval techniques are influenced by changes in atmospheric composition, including aerosols. Many empirically derived retrieval algorithms are based on matching Top of Atmosphere (TOA) Brightness Temperatures (BTs) from the Advanced Very High Resolution...
Show moreSea Surface Temperatures (SSTs) are an important measure of our current weather and climate, as well as an essential variable in both short and long term weather forecasting. Infrared SST retrievals are reliant on passive sensors, and retrieval techniques are influenced by changes in atmospheric composition, including aerosols. Many empirically derived retrieval algorithms are based on matching Top of Atmosphere (TOA) Brightness Temperatures (BTs) from the Advanced Very High Resolution Radiometer (AVHRR) to buoy measurements during clear-sky conditions. Data is cloud-cleared to remove cloud-contaminated data. However, small, but influential, Aerosol Optical Depths (AODs) data may not be flagged as contaminated and the algorithms incorrectly calculate a cold SST due to the radiometer sensing the cooler, elevated aerosol layer temperature. Many studies on aerosol effects on SSTs focus on aerosols due to volcanic eruptions. However, truly operational tropospheric aerosol corrections for daytime and nighttime retrievals have yet to be implemented. This work constitutes a first step to creating an accurate aerosol correction by exploring the sensitivity of aerosols on SSTs. The Santa Barbra DISORT Radiative Transfer model is used to quantify the effects of aerosol contamination on retrieved TOA BTs. The calculated radiances are spectrally averaged over each channel, converted to BTs, and used to calculate an SST using the Naval Oceanographic Office AVHRR algorithms. A radiative transfer model is used to evaluate the SST retrieval error due to varying AOD, height of an aerosol layer, and the satellite zenith angle (or viewing angle). This analysis shows that errors greater than the stated retrieval uncertainty of 0.5 K are observed for AODs greater than 0.25. Two sites with state-of-the-art aerosol measurements are analyzed for AOD variability. The first site, at Anmyon in east Asia, is found to have 14% of the days during the springtime with an AOD greater than 0.25. Based on the AERONET data from a second site in Cape Verde, 65% of the days during the boreal summer are found to have AOD greater than 0.25. Unfortunately, this seasonal peak in dust activity coincides with the active tropical cylogensis season for the region, making accurate SSTs even more vital for prediction purposes.
Show less
Date Issued: 2010
Identifier: FSU_migr_etd-3629
Format: Thesis

Title: Atmospheric Mercury Input to the Pensacola Bay Watershed.
Creator: Cleveland, Sara D., Landing, William M., Froelich, Philip, Huettel, Markus, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: By sampling individual rain events over a 1-year period at three sites situated around a known point source of atmospheric mercury, we have attempted to quantify its influence on local mercury deposition. A suite of trace elements was also analyzed on these rain event samples. A multi-element analytical program was set up using a Thermo-Finnigan "Element" ICP-MS. We identified 46 elements that are significantly enriched in rain samples relative to the method blank, including the alkali metals...
Show moreBy sampling individual rain events over a 1-year period at three sites situated around a known point source of atmospheric mercury, we have attempted to quantify its influence on local mercury deposition. A suite of trace elements was also analyzed on these rain event samples. A multi-element analytical program was set up using a Thermo-Finnigan "Element" ICP-MS. We identified 46 elements that are significantly enriched in rain samples relative to the method blank, including the alkali metals and alkaline earth elements, all three rows of the transition metals, and the rare earth elements. The total mercury concentrations in the rainwater samples ranged from 2-40 ng/L. The volume weighted mean rainfall mercury concentrations ranged from 9.2-9.8 ng/L, and there were no significant differences in the rainfall Hg deposition between the three sites. Principal component factor analysis (PCFA) was used to evaluate co-variance between mercury and trace element deposition. PCFA showed a strong crustal factor, a strong sea-salt factor, a mysterious "P" factor and a strong mercury factor. The mercury factor linked mercury with Bi, Ga, Pb, Sb and V. Plume dispersion modeling and air-mass back trajectory analysis have been conducted for each rain event. The goal of this research was to use mercury and trace element relationships in an effort to identify, and quantify, the impacts from various emission sources in the region on rainfall chemistry. We calculated the annual integrated percent of mercury associated with coal burning ranging between 15-47%. Using models to estimate the impact of local deposition we found that less than 1% of the mercury we measured is from the known point source.
Show less
Date Issued: 2006
Identifier: FSU_migr_etd-3582
Format: Thesis

Title: Applications of Calcareous Nannofossils and Stable Isotopes to Cenozoic Paleoceanography: Examples from the Eastern Equatorial Pacific, Western Equatorial Atlantic and Southern Indian Oceans.
Creator: Jiang, Shijun, Wise, Sherwood W., Iverson, Richard L., Arnold, Anthony J., Donoghue, Joseph F., Wang, Yang, Department of Earth, Ocean and Atmospheric Sciences, Florida State...
Show moreJiang, Shijun, Wise, Sherwood W., Iverson, Richard L., Arnold, Anthony J., Donoghue, Joseph F., Wang, Yang, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Show less
Abstract/Description: This dissertation is a collection of five calcareous nannofossil and one stable isotope studies on materials from Ocean Drilling Program (ODP) Legs 183 (Site 1135), 206 (Site 1256), and 207 (Site 1259) that target two important paleoceanographic events: 1) the middle/late Miocene carbonate crash, and 2) the Paleocene/Eocene Thermal Maximum (PETM). Site 1256 nannofossil biostratigraphy in Chapter 1 refined the author's shore-based shipboard Quaternary-middle-Miocene nannofossil biostratigraphy...
Show moreThis dissertation is a collection of five calcareous nannofossil and one stable isotope studies on materials from Ocean Drilling Program (ODP) Legs 183 (Site 1135), 206 (Site 1256), and 207 (Site 1259) that target two important paleoceanographic events: 1) the middle/late Miocene carbonate crash, and 2) the Paleocene/Eocene Thermal Maximum (PETM). Site 1256 nannofossil biostratigraphy in Chapter 1 refined the author's shore-based shipboard Quaternary-middle-Miocene nannofossil biostratigraphy with 16 zones/combined zones recognized based on 28 nannofossil datums. This chapter provides a chronologic framework for the age calibration of the first occurrence (7.18 Ma) and last occurrence (6.32 Ma) of Reticulofenestra rotaria, calculation of linear sedimentation rates, age determination of basalt basement (~14.5 Ma), and the recognition of the "carbonate crash" paleoceanographic event at the middle/late Miocene boundary. Reworked nannofossils and lithologic changes also allow a reading of a three-episode redepositional history (4.7, 8.3, and 10.7 Ma, respectively) in the eastern Pacific. The detailed examination of the Site 1256 material also yielded well-preserved Discoaster stellulus, for which only the distal view had been depicted in the original description. In Chapter 2, a redescription and re-illustration of both sides of this asterolith is provided. This should prevent misidentification of specimens in proximal view, thereby raising its potential application for middle-late Miocene biostratigraphy. Based on the above age model, in Chapter 3 stable oxygen and carbon isotopes were used for the first time to explore the late/middle Miocene "carbonate crash". This carbonate transition is a widespread (eastern and central equatorial Pacific, Indian, South Atlantic, and the Caribbean), sharp decrease in carbonate mass-accumulation rates, which has previously been considered only a dissolution event. The positive correlation (R2 = 0.75) between d13C and CaCO3 mass accumulation rates during 5-14 Ma at ODP Site 1256 clearly demonstrates that carbonate accumulation is mainly biologically controlled. The coincidence of the carbonate crash with negative excursions in d13C and d18O values suggests a causative mechanism related to surface-water productivity, as a result of surface-water warming and reduced upwelling. Based on these observations, one could speculate that the major middle/late Miocene sea-level drop may have caused the complete closure of the Indonesian Seaway, resulting in a piling-up of surface warm water in the west Pacific. The eastward spread of this nutrient-poor water then would have warmed sea-surface temperatures and reduced upwelling in the central and eastern Pacific, thereby creating a prolonged "El Nino" scenario and reducing biological productivity of phytoplankton. The reduction in carbonate supply to the deep waters consequently caused a rapid shoaling of the carbonate compensation depth, thereby triggering the carbonate crash. The PETM was a catastrophic, rapid greenhouse-forced global warming event ~55 m.y. ago that triggered an abrupt turnover in ocean chemistry and circulation as well as biota. Chapter 4 represents a quantitative study of the response of nannoplankton to the PETM at Demerara Rise, equatorial Atlantic (Site 1259). Toweius, Fasciculithus, and Chiasmolithus sharply decrease at the onset of the PETM, whereas Chiasmolithus, Markalius cf. M. apertus, and Neochiasmolithus thrive immediately after the event, which also signals the successive first appearances of Discoaster araneus, Rhomboaster, and Tribrachiatus. Two main environmental factors were extracted by correspondence analysis of relative abundance data. The time series of the two factors shows that during the PETM, 1) environmental stress (most likely from changes in seawater pH) increased and may well have also induced the evolution of ephemeral nannofossil "excursion taxa"; and 2) surface-water productivity increased at this site presumably due to higher runoff from continental areas. The local phytoplankton opportunist, Markalius cf. M. apertus, is described as a new species in Chapter 5, which will be published under the name Coccolithus bownii. Results presented in Chapter 6 from Site 1135 on the Kerguelen Plateau, Southern Ocean suggest that nannoplankton responded differently to the PETM at southern high latitudes. The onset of the carbon isotope excursion occurs within an 18-cm interval (instead of 1-2 cm as observed in most deep-sea sections) before the peak is reached, displaying a linear mixing curve. This indicates that the release of light carbon was a gradual, single injection, instead of multiple pulses as suggested in previous work, and that this sequence is highly expanded as a result of high sedimentation rates at this relatively shallow oceanic site. This is evidenced by the high numbers of dissolution-susceptible holococcoliths (Zygrhablithus bijugatus) preserved throughout the sequence. Although r- and K-selected specialists exponentially increase in abundance at the onset, Chiasmolithus abruptly drops but then rapidly recovers, whereas Discoaster and Fasciculithus show opposite trends, indicating that in high latitudes, surface-water oligotrophy prevailed at the carbon isotope excursion (CIE) onset but mesotrophic conditions dominated the CIE recovery. These observations confirm previous results from ODP Site 690 on Maud Rise. The intensive dissolution of susceptible holococcoliths and the poor preservation of the assemblages are believed to have been caused by the effects of corrosion caused by the methane release. The different responses of nannoplankton to the PETM and the contrasts evident in previous work from the open ocean vs the continental margins further demonstrate that the response to the PETM can be influenced by local differences in geologic setting and oceanographic conditions.
Show less
Date Issued: 2007
Identifier: FSU_migr_etd-3512
Format: Thesis

Title: The Variability of Certain Life-History Parameters of Early Juvenile Gag Grouper (Mycteroperca Microlepis, Pisces: Serranidae) in the Northern Gulf of Mexico.
Creator: Bourgoin, Stefan, Thistle, David, Koenig, Chris, Huettel, Markus, Chanton, Jeff, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Gag grouper, Mycteroperca microlepis, compose an important recreational and commercial fishery along the Gulf coast and Eastern Seaboard of the United States (Coleman et al. 2000, Morris et al. 2000, and Musick et al. 2000). Like many Serranids, gag have a complex life cycle in which juveniles spend each summer developing within inshore structured habitats before joining the adult population offshore (Heemstra and Randall 1993, Koenig et al. 1996, Grover et al. 1998). As is the case with most...
Show moreGag grouper, Mycteroperca microlepis, compose an important recreational and commercial fishery along the Gulf coast and Eastern Seaboard of the United States (Coleman et al. 2000, Morris et al. 2000, and Musick et al. 2000). Like many Serranids, gag have a complex life cycle in which juveniles spend each summer developing within inshore structured habitats before joining the adult population offshore (Heemstra and Randall 1993, Koenig et al. 1996, Grover et al. 1998). As is the case with most fisheries, heavy fishing pressures have led to a decline in gag abundance (Renan et al. 1996). The most efficient policies to mitigate for these population have as of yet focused on adult gag preservation; this study, however, attempt to use select juvenile gag population metrics (abundance and date of fertilization) to provide crucial data that may one day assist in providing a juvenile-centric population model. Over the course of a three-year study, juveniles were captured in two regions; near the Florida State University Coastal and Marine Laboratory (Turkey Point Shoal and Lanark Reef sites) and inside of Saint Andrew Bay, Panama City. Otolith analysis was performed to determine age and fertilization date of the juveniles, and abundance statistics were determined for each year. It was found that, consistent with previous literature, average fertilization date varied significantly across years and sampling sites (range = 41.9 to 91.8). The 2009 field season exhibited a significantly earlier fertilization date for both regions, and only one specimen was captured in Saint Andrew Bay. The 2009 Turkey Point Shoal field season was the only occurrence where abundance significantly declined during the course of the field season. Various environmental and physical factors may have been responsible for the enormous interannual variation seen in both abundance and fertilization date, such as large-scale current patterns and predator densities in the two regions. While no concrete conclusions may be drawn from the data, this study was essential in expanding on background knowledge of early juvenile gag population dynamics.
Show less
Date Issued: 2011
Identifier: FSU_migr_etd-3483
Format: Thesis

Title: Development of a New Storm Surge Index for Global Prediction of Tropical Cyclone Generated Storm Surge.
Creator: Jordan, Mark Rickman, Clayson, Carol Anne, Georgen, Jennifer, Hart, Robert, Ruscher, Paul, Ray, Peter, Cocke, Steven, Department of Earth, Ocean and Atmospheric Sciences,...
Show moreJordan, Mark Rickman, Clayson, Carol Anne, Georgen, Jennifer, Hart, Robert, Ruscher, Paul, Ray, Peter, Cocke, Steven, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Show less
Abstract/Description: This research involves the creation of a new storm surge index that incorporates many variables important in storm surge generation like maximum winds, radius of maximum winds, pressure, translation speed, and bathymetry. Using a two-dimensional, barotropic ocean model, power laws have been developed that describe the relationship between storm surge and changes in maximum wind, radius of maximum winds, pressure, and bathymetry. Direct curve fitting is used to describe the relationship...
Show moreThis research involves the creation of a new storm surge index that incorporates many variables important in storm surge generation like maximum winds, radius of maximum winds, pressure, translation speed, and bathymetry. Using a two-dimensional, barotropic ocean model, power laws have been developed that describe the relationship between storm surge and changes in maximum wind, radius of maximum winds, pressure, and bathymetry. Direct curve fitting is used to describe the relationship between storm surge and changes in translation speed since a power-law relationship does not exist in that case. A database of 39 landfalling, United States hurricanes between 1986 and 2007 is used to evaluate the quality of the index. Storm parameters for all database storms are compiled using the extended best track dataset, and an index value is calculated for each storm in the database. Correlation analysis is then performed using the index values and observed maximum storm surge heights. Finally, an extensive error analysis is presented to demonstrate uncertainties in the index in both forecast and post-analysis situations.
Show less
Date Issued: 2008
Identifier: FSU_migr_etd-3473
Format: Thesis

Title: Using the Superensemble Method to Improve Eastern Pacific Tropical Cyclone Forecasting.
Creator: Jordan, Mark Rickman, Krishnamurti, T. N., Clayson, Carol Anne, Ray, Peter S., Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: For many years tropical cyclone superensemble has shown remarkable skill in forecasting Atlantic tropical cyclone track and intensity. In this project tropical cyclone superensemble is applied to Eastern Pacific tropical cyclone forecasting for the 2004 Eastern Pacific tropical cyclone season. This task is completed by conducting a collection of model combination tests to discover which models perform best within the superensemble method. Then, the two main questions of this thesis are...
Show moreFor many years tropical cyclone superensemble has shown remarkable skill in forecasting Atlantic tropical cyclone track and intensity. In this project tropical cyclone superensemble is applied to Eastern Pacific tropical cyclone forecasting for the 2004 Eastern Pacific tropical cyclone season. This task is completed by conducting a collection of model combination tests to discover which models perform best within the superensemble method. Then, the two main questions of this thesis are addressed: will a combined Eastern Pacific and Atlantic training set provide superior forecasts over just using an Eastern Pacific training set, and do intensity-specific training sets provide superior forecasts over just using all storms of varying intensities? In the context of the 2004 Eastern Pacific tropical cyclone season, the answer to both questions is yes. However, the ultimate findings are quite perplexing, as an Atlantic training set provides superior forecasts when compared to forecasts using an Eastern Pacific training set or a combined-basin training set. Furthermore, forecasts made using only hurricane training usually outperform forecasts made using combined-intensity training and tropical storm training. The rest of the project uses model bias comparisons and intensity-specific error calculations to try and determine why the results are as they are.
Show less
Date Issued: 2005
Identifier: FSU_migr_etd-3472
Format: Thesis

Title: Two New Diosaccids (Copepoda, Harpacticoida) from the Northern Gulf of Mexico and Their Responses to Winter Storms.
Creator: Bouck, Lori, Thistle, David, Herrnkind, William, Iverson, Richard, Landing, William, Marcus, Nancy, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: The traditional method for producing taxonomic illustrations requires the preparation of inked copies of pencil originals. These individual figures are then grouped into plates for publication. I describe an alternative, computer-based approach. In a preliminary step, a pencil drawing is digitized and imported into an illustration program. The program's tools are then used to trace the image. Each figure is stored as a separate computer file. To make a plate for publication or a slide for...
Show moreThe traditional method for producing taxonomic illustrations requires the preparation of inked copies of pencil originals. These individual figures are then grouped into plates for publication. I describe an alternative, computer-based approach. In a preliminary step, a pencil drawing is digitized and imported into an illustration program. The program's tools are then used to trace the image. Each figure is stored as a separate computer file. To make a plate for publication or a slide for presentation, several figures can be combined. The approach has several advantages. (1) It is easier to master than the pen-and-ink method. (2) Figures can be manipulated electronically, so the size and orientation of a figure is infinitely adjustable, providing great flexibility in the preparation of plates. (3) Multiple "originals" can be printed. (4) Mistakes can be corrected easily. I describe two new species of Diosaccidae (Harpacticoida, Copepoda) from an unvegetated sand at 18 m depth in the northern Gulf of Mexico. One is assigned to the genus Protopsammotopa; the other is assigned to Actopsyllus, and traits in common with Eoschizopera Wells & Rao (1976) are noted. I used the computer-based techniques to produce the figures for these descriptions. The effects of winter storms on the two new diosaccids described here were studied through a reanalysis of data from Thistle et al. (1995a). I found that Actopsyllus sp. nov. did not migrate downward in response to erosive flow. Protopsammotopa sp. nov. males, but not females, did. Protopsammotopa sp. nov. is found at shallower depths in the sediment than Actopsyllus sp. nov., which may explain the difference in response to erosion by two morphologically similar and phylogenetically related species.
Show less
Date Issued: 2003
Identifier: FSU_migr_etd-3492
Format: Thesis

Title: Characterization of Arsenic Upon Liming and Formation of Residual NAPL in the Vadose Zone.
Creator: Das, Nabanita Raha, Dudley, Lynn, Krishnamurti, Ruby, Ye, Ming, Tull, James F., Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Incorporation of lime amendments is an effective treatment to neutralize acidity, reduce soluble metals, and facilitate plant growth in mine wastes. In general, arsenic (As) solubility increases with increasing pH in As laden mine wastes. However, a number of laboratory and field studies have shown the decrease in As solubility with increase in pH. It has been hypothesized that reduction in soluble As was likely due to presence of amorphous oxides of iron, aluminum and manganese. Further, in...
Show moreIncorporation of lime amendments is an effective treatment to neutralize acidity, reduce soluble metals, and facilitate plant growth in mine wastes. In general, arsenic (As) solubility increases with increasing pH in As laden mine wastes. However, a number of laboratory and field studies have shown the decrease in As solubility with increase in pH. It has been hypothesized that reduction in soluble As was likely due to presence of amorphous oxides of iron, aluminum and manganese. Further, in experimental studies it has been seen that the total concentration of Fe+Al+Mn was approximately ten times higher in the mine wastes exhibiting decrease in soluble As. There was no correlation suggested with any single element. This study uses PHREEQC for geochemical modeling to investigate the factors and reaction pathways affecting changes in soluble-As concentrations upon liming acidic metalliferous mine wastes. The results indicate that a change in solubility of As upon liming is mainly affected by the presence of amorphous phases of aluminum. Iron and manganese oxides don't play a significant role. Managing contaminated sites (due to infiltration of NAPL) can be expensive, but multiphase models can be an effective tool to predict the subsurface behavior of contaminants and help reduce associated costs. One of the major deficiencies of such models is the prediction of the amount of residual non-aqueous phase liquids (NAPL). In order to accurately predict the behavior of residual NAPL, it is important to understand the formation of residual NAPL. The presence of residual NAPL in the vadose zone has been demonstrated by many researchers, but the conditions under which residual NAPL is formed are poorly understood. Traditionally permeability-saturation-pressure (k-s-p) relations have been used to demonstrate the formation of residual NAPL. Herein, we use electrical conductivity to investigate the process of formation of residual NAPL. Results from the experiments indicate formation of residual NAPL during drainage of NAPL from the system. Further, experimental studies ware undertaken to validate the model presented by Wipfler and van der Zee (2001) with experimental data set in which both oil and water pressure head are determined. Natural soil sample was used instead of Ottawa sand. Ottawa sand has a more uniform grain size than soils so this series of experiments tests the model in a more complex system. Another difference between previous studies and this experiment was the choice of NAPL. Oleic acid, which is a light NAPL was used herein instead of the dense NAPL used by Hofstee et al. (1997). Results from the experiments indicate that the model failed to predict the formation of the residual NAPL under the experimental conditions.
Show less
Date Issued: 2011
Identifier: FSU_migr_etd-5584
Format: Thesis

Title: Mesoscale Superensemble Forecasts with a Suite of Models over the Continental United States and North America.
Creator: Van Dyke, Donald F., Krishnamurti, T. N., Hart, Robert, Ruscher, Paul, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Using a suite of high resolution models, the forecast skills of the superensemble for precipitation and 2-meter temperature over the continental United States and North America are shown. In this study, models and/or gridded fields such as the ETA, WRFARW, MM5, NDFD, several global models, and their ensemble mean are used. The final resolution for the multimodel superensemble is at 32 km at 3-hourly temporal intervals for temperature and ¼ degree daily intervals for precipitation. The...
Show moreUsing a suite of high resolution models, the forecast skills of the superensemble for precipitation and 2-meter temperature over the continental United States and North America are shown. In this study, models and/or gridded fields such as the ETA, WRFARW, MM5, NDFD, several global models, and their ensemble mean are used. The final resolution for the multimodel superensemble is at 32 km at 3-hourly temporal intervals for temperature and ¼ degree daily intervals for precipitation. The forecast length is 60 hours for temperature and 5 days for precipitation. This study utilizes an optimization for the training length (number of days) to arrive at the best results. The period of the study includes March-September 2006. The metrics for the forecast evaluation include the mean absolute error, rms error, bias, and equitable threat scores. The results show a significant improvement of the multimodel superensemble compared to its member models and their ensemble mean.
Show less
Date Issued: 2007
Identifier: FSU_migr_etd-4585
Format: Thesis

Title: An Ingredients-Based Examination of U.S. Severe Tornado Alleys Using Reanalysis Data.
Creator: Vickers, Grayum, Chassignet, Eric, Hart, Robert, Bourassa, Mark, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: A new metric for identifying severe tornado (F3+) alleys is presented. Regions are distinguished by average F-scale values with a minimum of 15 severe tornado events within 200km. Five distinct "severe tornado alleys" are described across the United States: 1) the Carolinas, 2) "Dixie Alley," 3) Kansas and Oklahoma, 4) Iowa and Nebraska, and 5) Wisconsin, Illinois, Indiana and Michigan. These regions are evaluated using CFSR global reanalysis data to determine the presence of atmospheric...
Show moreA new metric for identifying severe tornado (F3+) alleys is presented. Regions are distinguished by average F-scale values with a minimum of 15 severe tornado events within 200km. Five distinct "severe tornado alleys" are described across the United States: 1) the Carolinas, 2) "Dixie Alley," 3) Kansas and Oklahoma, 4) Iowa and Nebraska, and 5) Wisconsin, Illinois, Indiana and Michigan. These regions are evaluated using CFSR global reanalysis data to determine the presence of atmospheric variables relating to tornadogenesis (as described by prior work) in the pre-tornadic environments. Composite CFSR soundings and composite field charts are created for severe tornado events within each region. A robust comparison of pre-tornadic atmospheric conditions among regions is conducted using a Student t-test at 95% confidence.. An evaluation of the Sigtor parameter, a commonly used significant tornado forecast parameter developed by the Storm Prediction Center, is also conducted to identify regional variability. It is found that each region significantly differs at 95% confidence from each other in terms of many atmospheric variables from pre-tornadic environments, with the most significant differences existing between the two more eastern and two mid-western regions. SigTor values and the individual components, are calculated for severe tornado events and for every time-step for every grid-point within each region over a "peak severe tornado season" for U.S. severe tornadoes in order to compare the event cases to a background mean state. It is shown using linear correlations and covariances of the individual terms of the Sigtor parameter to the Sigtor value that not only is there discrepancy in Sigtor values between regions, but the different components of SigTor contribute to the value of Sigtor in different ways between regions. Some regions show background values of Sigtor terms to be favorable for tornadogenesis even when tornadoes have not occurred. Regional biases in presence of atmospheric variables preceding severe tornado events between regions are described.
Show less
Date Issued: 2012
Identifier: FSU_migr_etd-5452
Format: Thesis

Title: Characteristics and GFS Forecast Accuracy of Intraseasonal Shifts in the Arctic Oscillation Index.
Creator: Visco, Travis Connor, Fuelberg, Henry E., Hart, Robert E., Sura, Philip, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: This study evaluates the characteristics and forecast accuracy of the Arctic Oscillation (AO) Index on an intraseasonal time scale. The Arctic Oscillation is a natural pattern of time varying sea-level pressure anomalies that is one of the leading modes of weather variability in the Northern Hemisphere. Sustained shifts in the AO Index can lead to pronounced and sudden changes in weather patterns that can have dramatic economic and social impacts. Previous studies have described...
Show moreThis study evaluates the characteristics and forecast accuracy of the Arctic Oscillation (AO) Index on an intraseasonal time scale. The Arctic Oscillation is a natural pattern of time varying sea-level pressure anomalies that is one of the leading modes of weather variability in the Northern Hemisphere. Sustained shifts in the AO Index can lead to pronounced and sudden changes in weather patterns that can have dramatic economic and social impacts. Previous studies have described characteristics and trends in the AO, but on seasonal and decadal time scales. Focusing on short time scales that can be depicted by Numerical Weather Prediction models, this study describes the AO's influence on surface temperature and the ability of the Global Forecast System (GFS) and Global Ensemble Forecast System (GEFS) numerical models to forecast changes in the AO index. Forecast performance is investigated over a range of atmospheric conditions from 2000-2011. Evaluation metrics include Probability of Detection, False Alarm Rate, and Critical Success Index. In addition, average forecast error is quantified through the use of absolute error calculations. Together, it is presented which evaluation techniques best enhance the AO Index forecast accuracy of the GFS and GEFS models, along with the expected forecast error that the models and methodologies provide. Results conclude that shorter period forecasts that utilize smoothing filters produce the best model performance with the least forecast error. The GFS and GEFS models have enhanced performance when the strength of the shift in the AO Index is sufficiently large (> 2 standard deviations). In addition, during the highly variable winter, forecast performance is largely diminished.
Show less
Date Issued: 2012
Identifier: FSU_migr_etd-5453
Format: Thesis

Theses and Dissertations (261)	+ -
Undergraduate Honors Theses (9)	+ -
Digitized Theses and Dissertations (1)	+ -

Atmospheric sciences (232)	+ -
Meteorology (124)	+ -
Earth sciences (117)	+ -
Geophysics (109)	+ -
Atmospheric physics (3)	+ -

Climatic changes (2)	+ -
Ecology (2)	+ -
Evolution (Biology) (2)	+ -
Benthos (1)	+ -
Environmental sciences (1)	+ -
Fresh water (1)	+ -
Geography (1)	+ -
Interstitial animals (1)	+ -
Mathematics (1)	+ -

text (270)	+ -
doctoral thesis (4)	+ -
master thesis (2)	+ -

Florida State University (261)	+ -
Department of Earth, Ocean and Atmospheric Sciences (248)	+ -
Hart, Robert (39)	+ -
Liu, Guosheng (39)	+ -
Huettel, Markus (27)	+ -

Search In

Pages

Pages

Sort Results By:

Narrow results by:

Collection

Topical Subject

Genre

Type of Resource

Language

Creator

Owner