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Title: The Accuracy of the National Hurricane Center's United States Tropical Cyclone Landfall Forecasts in the Atlantic Basin (2004–2012).
Creator: Keclik, Alexandra, Department of Earth, Ocean and Atmospheric Sciences
Abstract/Description: This study examined the position, timing, and intensity of each National Hurricane Center's (NHC) Official Forecasts (OFCL) for Atlantic tropical storms and hurricanes that made landfall in the United States from 2004 to 2012. During that time period, one hundred and fifty tropical cyclones developed in the Atlantic basin. Thirty-two of the cyclones made landfall in the United States as tropical storms or hurricanes. Accurate predictions of the location, timing, and intensity of tropical...
Show moreThis study examined the position, timing, and intensity of each National Hurricane Center's (NHC) Official Forecasts (OFCL) for Atlantic tropical storms and hurricanes that made landfall in the United States from 2004 to 2012. During that time period, one hundred and fifty tropical cyclones developed in the Atlantic basin. Thirty-two of the cyclones made landfall in the United States as tropical storms or hurricanes. Accurate predictions of the location, timing, and intensity of tropical cyclone landfalls are important, so that people in a storm's track can prepare adequately for heavy to catastrophic wind, rain, and storm surge. The errors of each of the OFCL for Atlantic tropical storms and hurricanes that made landfall in the United States during 2004–2012 are acquired from the Best Track data set. The ELTOPO1 landmask is used to find the forecasted landfall point using sequential locations from the OFCL offshore and onshore points of each forecast. The great circle distance between the forecasted and actual landfall constitutes the location error. The official landfall time is subtracted from the forecasted landfall time to find the timing error, and the official landfall wind speed is subtracted from the closest to onshore wind speed to find intensity error. There is a trend of decreasing error in location, timing, and intensity forecasting with decreasing lead time. An improvement in tropical cyclone landfall forecasting is found from comparing the 2004–2012 Atlantic landfall forecast errors to those in a study of 1976-2000 forecasts.
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Date Issued: 2014
Identifier: FSU_migr_uhm-0324
Format: Thesis

Title: Analysis of Convective Transport of Biomass Burning Emissions in Southeast Asia.
Creator: Ahern, Kyle, Department of Earth, Ocean and Atmospheric Sciences
Abstract/Description: Biomass burning and anthropogenic emissions affect the composition of the atmosphere, thereby impacting global climate and health. Deep convective processes can loft emissions from the boundary layer into the upper troposphere or lower stratosphere (UTLS). Strong upper-level winds can potentially transport the emissions over long distances. This study focused on the deep convective transport of biomass burning emissions near the Strait of Malacca during summer. The Weather Research and...
Show moreBiomass burning and anthropogenic emissions affect the composition of the atmosphere, thereby impacting global climate and health. Deep convective processes can loft emissions from the boundary layer into the upper troposphere or lower stratosphere (UTLS). Strong upper-level winds can potentially transport the emissions over long distances. This study focused on the deep convective transport of biomass burning emissions near the Strait of Malacca during summer. The Weather Research and Forecasting (WRF) and Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT_4) models were used to investigate deep convection and the transport of emissions from fires in the region. Fire data from the Moderate-resolution Imaging Spectroradiometer (MODIS) sensors onboard the Aqua and Terra satellites provided locations of fire emissions. These fire datasets were obtained from the University of Maryland's Fire Information for Resource Management System (FIRMS). To investigate the deep convective processes thoroughly, this study used high resolution modeling (4 km grid spacing) to resolve the convection explicitly. Explicit resolution allows the thunderstorms to be simulated more realistically than would parameterization, thus making it ideal for this research. Results showed that deep convection occurring in the Strait of Malacca is driven primarily by diurnal heating patterns and the region's topography. Convection in the region is frequent and scattered, but follows a cyclic diurnal pattern: convection over land during daytime and over the Strait during nighttime. When emissions from fires encounter areas of deep convection, they are quickly lofted to the UTLS where winds then transport them elsewhere.
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Date Issued: 2013
Identifier: FSU_migr_uhm-0216
Format: Thesis

Title: The Increasing Intensity and Frequency of ENSO and its Impacts to the Southeast U.S.
Creator: McNaught, Carlysle, Department of Earth, Ocean and Atmospheric Sciences
Abstract/Description: The El Niño Southern Oscillation (ENSO) is an important natural climate variation that affects large portions of the world. The changing magnitude and frequency of ENSO reveals that it is getting stronger as measured by the maximum anomaly in sea surface temperature (SST). Principal component analysis of the ENSO is conducted to estimate the spectrum of the SST of the time series. The intensity of the ENSO events during the period 1970—2010 is statistically significantly higher when compared...
Show moreThe El Niño Southern Oscillation (ENSO) is an important natural climate variation that affects large portions of the world. The changing magnitude and frequency of ENSO reveals that it is getting stronger as measured by the maximum anomaly in sea surface temperature (SST). Principal component analysis of the ENSO is conducted to estimate the spectrum of the SST of the time series. The intensity of the ENSO events during the period 1970—2010 is statistically significantly higher when compared to the period 1930—1970, with a broad spectral peak centered around 4 years. When we compare the SST spectrum for the period 1930—1970 with the spectrum for 1970—2010, we find the latter period to be much stronger in power. The resultant impact of more powerful and frequent ENSO events on the Southeast United States is examined through a spatial and temporal statistical analysis of precipitation and temperatures between the two time periods. Our analysis reveals statistically significant changes in precipitation during El Niño where the rainfall is much more widespread across the Southeast during the 1970—2010 period than the 1930—1970 period. The La Niña rainfall deficit is mainly confined to Florida in the latter period than the former. Finally, the temperature distribution, through an analysis of the first four statistical moments, showed conventional responses to the changes in ENSO precipitation such as an anomalous decrease in maximum temperatures during El Niño and an overall anomalous increase in temperatures during La Niña.
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Date Issued: 2014
Identifier: FSU_migr_uhm-0356
Format: Thesis

Title: Examining Shifts in Warm-Season Near-Surface Moisture Trends in Florida.
Creator: Swearingen, Aaron D., Department of Earth, Ocean and Atmospheric Sciences
Abstract/Description: Warm-season (1 June–31 August) near-surface moisture trends have been examined across Florida. Data was used from 86 National Weather Service cooperative stations, 24 NWS first-order stations, and the European Centre for Medium-Range Weather Forecasts' ERA-Interim satellite reanalysis. Seventy-five out of eighty-six NWS cooperative stations depicted high counts of maximum low temperature records being set or broken since 1990. Twenty-four NWS hourly stations were used in conjunction with the...
Show moreWarm-season (1 June–31 August) near-surface moisture trends have been examined across Florida. Data was used from 86 National Weather Service cooperative stations, 24 NWS first-order stations, and the European Centre for Medium-Range Weather Forecasts' ERA-Interim satellite reanalysis. Seventy-five out of eighty-six NWS cooperative stations depicted high counts of maximum low temperature records being set or broken since 1990. Twenty-four NWS hourly stations were used in conjunction with the Pettitt test to calculate a change point of 1990 over a 40-year period (1973–2012). Using the Pettitt results, a significant amount of NWS first-order stations depicted a rise in both early morning temperatures and dew points (Td) since 1990. A rise in total column water vapor (TCWV) was detected through the ERA-Interim reanalysis, indicating a possible increase in mid-level moisture in addition to that near the surface. A reversal in 850 hPa wind patterns and a potential shift in the Azores High were present in the reanalysis as well. An increase in atmospheric moisture levels is present and may be driven by synoptic-scale changes in wind patterns due to a shift in the Azores High.
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Date Issued: 2015
Identifier: FSU_migr_uhm-0528
Format: Thesis

Title: A High Resolution Atmospheric Chemistry Simulation of Hurricane Sandy (2012).
Creator: Freeman, Sean, Department of Earth, Ocean and Atmospheric Sciences
Abstract/Description: Hurricane Sandy (2012) had one of the greatest economic impacts of any hurricane in United States history. However, its broader scientific impacts, especially its impacts on the chemistry of the upper troposphere and lower stratosphere, have not been documented. This study uses the Weather Research and Forecasting with Chemistry model (WRF-Chem), run at a convective-permitting resolution, to examine the transport of pollutants inside Hurricane Sandy as it made landfall along the Eastern...
Show moreHurricane Sandy (2012) had one of the greatest economic impacts of any hurricane in United States history. However, its broader scientific impacts, especially its impacts on the chemistry of the upper troposphere and lower stratosphere, have not been documented. This study uses the Weather Research and Forecasting with Chemistry model (WRF-Chem), run at a convective-permitting resolution, to examine the transport of pollutants inside Hurricane Sandy as it made landfall along the Eastern Seaboard. Although several pollutants were examined, the concentrations of CO throughout the atmosphere and the transport of CO from sources along the coast in Hurricane Sandy's convective region were primary focus. A forward-trajectory analysis also was performed using the high-resolution WRF-Chem data as input to the Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT). The results of this high-resolution chemical and meteorological simulation will be presented with a focus on transport to the upper troposphere and lower stratosphere. To our knowledge, such high-resolution chemical and meteorological simulations of tropical cyclones have not been reported in the previous literature.
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Date Issued: 2015
Identifier: FSU_migr_uhm-0477
Format: Thesis

Title: Stratospheric Polar Vortex Warming and Cold Air Outbreaks: A Case Study.
Creator: Perrini, Nikki, Department of Earth, Ocean and Atmospheric Sciences
Abstract/Description: The predictability of the stratospheric circulations and the connection between the stratospheric branch and cold air branch allow us to predict large continental-scale cold air outbreaks with ample lead-time. Based on this, we have made experimental sub-seasonal forecasts for cold air outbreaks across the mid-latitude regions of North America, Europe, and Eastern Asia. The forecasts made in this winter have provided the public with a lead-time of 20-45 days for individual cold air outbreak...
Show moreThe predictability of the stratospheric circulations and the connection between the stratospheric branch and cold air branch allow us to predict large continental-scale cold air outbreaks with ample lead-time. Based on this, we have made experimental sub-seasonal forecasts for cold air outbreaks across the mid-latitude regions of North America, Europe, and Eastern Asia. The forecasts made in this winter have provided the public with a lead-time of 20-45 days for individual cold air outbreak events. This thesis also made a case study of a strong stratospheric circulation event called "STRAT_E", which had the longest duration and was the most intense cold air outbreak episode. The case study helps to further explain the processes behind cold air outbreaks.
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Date Issued: 2015
Identifier: FSU_migr_uhm-0535
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.
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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.
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Date Issued: 2014
Identifier: FSU_migr_uhm-0564
Format: Thesis

Title: Investigating Relationships Between Rising Temperatures and Heavy Rainfall Events in the Southeastern U.S. Using Analog Methods.
Creator: Zuromski, Lauren, Department of Earth, Ocean and Atmospheric Sciences
Abstract/Description: This study examines how extreme precipitation influences temperatures, and how temperature extremes influence precipitation in the Southeastern U.S., seasonally, using observational data. For the precipitation influencing temperature approach, three precipitation regimes are created (wet, dry, and neutral) to observe possible shifts in the distributions of seasonal average daily maximum and minimum temperatures based on precipitation extremes. Similarly, for the temperature influencing...
Show moreThis study examines how extreme precipitation influences temperatures, and how temperature extremes influence precipitation in the Southeastern U.S., seasonally, using observational data. For the precipitation influencing temperature approach, three precipitation regimes are created (wet, dry, and neutral) to observe possible shifts in the distributions of seasonal average daily maximum and minimum temperatures based on precipitation extremes. Similarly, for the temperature influencing precipitation, three temperature regimes are created (warm, cool, and neutral), to observe how the frequency of rainfall events of 1.00" or more shifts in each temperature regime. For the precipitation influencing temperature approach, most notably, it is found that in summer, spring, and fall, in a wet precipitation regime, the maximum temperatures are typically warmer (cooler) than the average maximum temperatures in a neutral regime; the opposite pattern is observed for winter. It is also found that these temperature distributions do not shift in a uniform way across the Southeast, though several regional continuities exist. For the temperature influencing precipitation approach, it is found that spring, summer, and winter show the largest differences in the frequency of rainfall events of 1.00" or more between the cool and warm temperature regimes. This study also examines five case study stations in the Southeast to observe regional nuances in temperature and precipitation patterns.
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Date Issued: 2015
Identifier: FSU_migr_uhm-0511
Format: Thesis

Title: IC to CG Lightning Relationships over the Tallahassee CWA.
Creator: Jackson, Karly M., Department of Earth, Ocean and Atmospheric Sciences
Abstract/Description: The formation of and the relationship between intra-cloud (IC) and cloud-to-ground (CG) lightning flashes have not been thoroughly studied. Understanding how these flash types interact in different types of thunderstorms can lead to a better understanding of lightning characteristics and how these characteristics can be applied to operational forecasting practices. Results of this study show that the IC:CG ratio varies greatly each day throughout the summer season over the County Warning Area...
Show moreThe formation of and the relationship between intra-cloud (IC) and cloud-to-ground (CG) lightning flashes have not been thoroughly studied. Understanding how these flash types interact in different types of thunderstorms can lead to a better understanding of lightning characteristics and how these characteristics can be applied to operational forecasting practices. Results of this study show that the IC:CG ratio varies greatly each day throughout the summer season over the County Warning Area (CWA) of the Tallahassee National Weather Service Forecast Office. The summer season is dominated by daily thunderstorms that form due to sea breeze fronts and their resulting outflow boundaries. Eleven case study storms reveal how IC and CG flash counts and rates in non-severe thunderstorms differ from those of severe storms such as those examined by Williams et al. (1999). Results of the present study reveal that the timing of CG lightning and the frequency of its strikes differ from those of severe storms. This is most likely due to severe storms producing stronger updrafts for longer periods of time than those of non-severe storms. The IC:CG ratios varied greatly among these case studies indicating that further studies must be done to determine a statistically significant understanding of how flash rates change and how the relationship between IC and CG flashes relate to the ratios they produce.
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Date Issued: 2015
Identifier: FSU_migr_uhm-0552
Format: Thesis

Title: Remotely Sensed Validation of Numerical Weather Prediction Estimates of Wind Speed Near Tropical Cyclones.
Creator: Dacey, Connor, Department of Earth, Ocean and Atmospheric Sciences
Abstract/Description: This study examined the tendencies of the European Center for Medium-Range Weather Forecasting Ensemble Prediction System (ECMWF-EPS) control forecast of wind speeds near two rapidly intensifying tropical cyclones (TCs) in the Indian Ocean. The ECMWF-EPS control forecasts were compared with the Advanced Scatterometer (ASCAT) wind speed measurements, which were considered comparison and "truth" data for this study. In total, 6 days of model forecast and ASCAT data were collected and analyzed...
Show moreThis study examined the tendencies of the European Center for Medium-Range Weather Forecasting Ensemble Prediction System (ECMWF-EPS) control forecast of wind speeds near two rapidly intensifying tropical cyclones (TCs) in the Indian Ocean. The ECMWF-EPS control forecasts were compared with the Advanced Scatterometer (ASCAT) wind speed measurements, which were considered comparison and "truth" data for this study. In total, 6 days of model forecast and ASCAT data were collected and analyzed for severe tropical cyclones Phet and Giri. Differences in the magnitudes of the wind speeds near the TCs were calculated. From these, areas can be seen in which the ECMWF-EPS control over-forecasted and under-forecasted the wind speeds. These results also help explain how the model tendencies changed throughout the lifespan of the TCs. Overall, wind speed errors were greatly associated with errors in storm location, storm shape, and storm size. No exact conclusion about the tendencies of the ECMWF-EPS control forecasts could be made due to a lack of patterns or clear biases associated with the wind speed difference results. A more in-depth study must be completed to further comment on specific tendencies of the model. Nevertheless, this study could begin the investigation into how to improve wind speed forecasts for TCs in the Indian Ocean in an effort to better save life and property in the future.
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Date Issued: 2015
Identifier: FSU_migr_uhm-0548
Format: Thesis

Title: An Examination of the Differences in Tropical Cyclone Pressure-Wind Relationships Among Observations, Model Analyses, and Model Forecasts.
Creator: Visin, Lauren, Department of Earth, Ocean and Atmospheric Sciences
Abstract/Description: Despite significant advances in tropical cyclone (TC) track forecasting over the past few decades, intensity forecasts remain problematic, even for high-resolution computer models uniquely developed and tailored to TC prediction. This study examines the ability of two of these models, the Geophysical Fluid Dynamics Laboratory (GFDL) model and the Hurricane Weather Research and Forecasting (HWRF) model, to analyze and predict one measure of TC structure in the Atlantic Basin. Instead of more...
Show moreDespite significant advances in tropical cyclone (TC) track forecasting over the past few decades, intensity forecasts remain problematic, even for high-resolution computer models uniquely developed and tailored to TC prediction. This study examines the ability of two of these models, the Geophysical Fluid Dynamics Laboratory (GFDL) model and the Hurricane Weather Research and Forecasting (HWRF) model, to analyze and predict one measure of TC structure in the Atlantic Basin. Instead of more conventional evaluations based solely on a TC's maximum wind speed or minimum sea level pressure (MSLP), the relationship between these two variables is used: a TC's pressure-wind relationship (PWR), which gives a more detailed look at how well each model analyzes and forecasts TC structure. The analysis begins in 2007, the year the GFDL was initially "frozen" (development and improvements were ceased) and also the first year that the HWRF was used for operational forecasting. Comparison of both GFDL and HWRF analyses and forecasts to the National Hurricane Center's (NHC) "best track" (database of 6-hourly observations of vital statistics such as maximum wind speed and MSLP for all TCs) revealed that, while both models produced errors in their analyses and forecasts, the GFDL outperformed the HWRF in both analysis and forecasting of TC PWR's for Atlantic Basin hurricanes from 2007-2013.. There was a subsection of particularly strong TCs (maximum winds above 120kt, MSLP lower than 950mb) whose structure was forecast especially poorly. The forecast PWR's produced by the HWRF fell largely outside the "best track" for this set of intense TCs, suggesting that the structures produced by the HWRF are inconsistent with our best estimates of observations in the Atlantic Basin and given current climate conditions. The PWR distribution evolved considerably for the HWRF over time, presumably as model improvements were made (including a decrease in model gridspacing). This has led to the model analysis PWR becoming more consistent with the model forecast PWR envelope. Nonetheless, both often fall outside the best-track estimates of PWR and potential explanations for this disparity are presented.
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Date Issued: 2014
Identifier: FSU_migr_uhm-0386
Format: Thesis

Title: Structural Emplacement and Stratigraphic Setting of Eastern Blue Ridge Plutonic Complexes and Associated Lithologies, Alabama Appalachians.
Creator: Pazel, John, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: pending
Date Issued: 2012
Identifier: FSU_migr_etd-5101
Format: Thesis

Title: Diabatic Processes Modifying the Structure and Evolution of Idealized Baroclinic Life Cycle Simulations.
Creator: Glasser, Daisy, Chagnon, Jeffrey M., Cai, Ming, Liu, Guosheng, Florida State University, College of Arts and Sciences, Department of Earth, Ocean, and Atmospheric Science
Abstract/Description: Diabatic processes including latent heating and radiation are parameterized in numerical weather prediction (NWP) models and constitute a major source of error. Isolating the extent of diabatic modification in an extratropical cyclone in observational atmospheric data is difficult. This study analyzes four idealized Advanced Weather Research and Forecasting (WRF-ARW) model sensitivity experiments in which radiation or moisture are either included or withheld. The experiments consist of the...
Show moreDiabatic processes including latent heating and radiation are parameterized in numerical weather prediction (NWP) models and constitute a major source of error. Isolating the extent of diabatic modification in an extratropical cyclone in observational atmospheric data is difficult. This study analyzes four idealized Advanced Weather Research and Forecasting (WRF-ARW) model sensitivity experiments in which radiation or moisture are either included or withheld. The experiments consist of the following: no radiation and no moisture (NRNM), radiation and no moisture (RNM), moisture and no radiation (NRM), and radiation and moisture (RM). Simulations are of an idealized baroclinic wave in the midlatitudes. Because baroclinic waves are associated with synoptic scale weather events, these WRF-ARW simulations are the ideal platform to better understand the interactions of diabatic and dynamic processes. Inclusion of moisture and radiation has a significant impact on baroclinic wave structure and evolution. On the synoptic scale, the RM experiment demonstrates greatest amplification/depth, earliest growth, and was the only experiment with cyclonic breaking in the troposphere and high amplitude anticyclonic breaking in the lower stratosphere. On the sub-synoptic scale, vertical dipoles in isentropic potential vorticity (IPV) and cloud-scale anomalies developed in the middle to upper troposphere as the wave matured. While radiation alone yields no anomaly, and moisture alone yields a small anomaly, the inclusion of radiation and moisture together yields a significantly larger IPV anomaly. Anomalies may be due to constructive interference or nonlinear feedbacks between radiative cooling and latent heating. Results of this study have important implications for NWP, especially in the representation of physical processes via parameterization schemes. Knowledge gained about physical processes and their feedbacks on resolved flow might help to better understand error and bias in NWP models.
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Date Issued: 2016
Identifier: FSU_2016SU_Glasser_fsu_0071N_13462
Format: Thesis

Title: Relationship Between Meridional Mass Circulation and Extreme Temperature Events in the Southern Hemisphere.
Creator: Yan, Ruikai, Cai, Ming, Chagnon, Jeffrey M., Liu, Guosheng, Florida State University, College of Arts and Sciences, Department of Earth, Ocean, and Atmospheric Science
Abstract/Description: This study explores extreme surface temperature events in Southern Hemisphere winter (June – August) from 1979 to 2011 and their relation with meridional mass circulation by using daily ERA-interim Re-Analysis data from European Center for Medium-Range Weather Forecasts (ECMWF). Meridional mass circulation indices are developed to quantitatively represent the warm air mass being transported into the polar region in the upper atmosphere and the cold air mass being transported out of the polar...
Show moreThis study explores extreme surface temperature events in Southern Hemisphere winter (June – August) from 1979 to 2011 and their relation with meridional mass circulation by using daily ERA-interim Re-Analysis data from European Center for Medium-Range Weather Forecasts (ECMWF). Meridional mass circulation indices are developed to quantitatively represent the warm air mass being transported into the polar region in the upper atmosphere and the cold air mass being transported out of the polar region in the lower atmosphere. Our results show that weaker poleward warm air mass transport aloft is associated with weaker cold air transport toward equator in the lower troposphere, resulting in cold air being confined in the polar regions. Similarly, stronger poleward warm air mass transport in the upper atmosphere is related to stronger cold air transport out of the polar regions, causing enormous cold air outbreaks in the mid-latitude regions. We find that regions to the south of 45S exhibit a robust relationship between surface air temperature anomalies and meridional mass circulation. Weaker circulation is associated with abnormally cold in Antarctica and abnormally warm in regions from 45S to 60S. Conversely, stronger circulation is related to anomalously warm in Antarctica and anomalously cold in the surrounding continental shelf, particularly over Weddell-Scotia Sea and north Ross Sea where are the two preferred routes for cold air coming out of Antarctica. On the other hand, temperature anomalies over the regions north of 45S are not sensitive to the meridional circulation variability. The fact that surface air temperature anomalies over the Southern Ocean rarely exceed 4C suggests that cold air coming out of Antarctic has limited impacts on the Southern Ocean due to its large thermal inertia. In summary, the meridional mass circulation indices provide a robust diagnostics for extreme cold events in 45S - 90S domain very well, but may not be adequate to describe all cold events over the vast mid-latitude regions in the Southern Hemisphere.
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Date Issued: 2016
Identifier: FSU_2016SP_Yan_fsu_0071N_13259
Format: Thesis

Title: Trophic Ecology and Bioaccumulation of Mercury in the Three Hagfish (Myxinidae) Species from the Gulf of Mexico.
Creator: Mickle, Alejandra, Chanton, Jeffrey P., Landing, William M., Florida State University, College of Arts and Sciences, Department of Earth, Ocean, and Atmospheric Science
Abstract/Description: Hagfishes (Myxinidae) are common in deep waters of the Gulf of Mexico (GOM). Two of the species found in the GOM are endemic to the area and potentially provide key ecosystem services (e.g. generate substrate turnover and recycling of organic matter by consuming carrion falls) to the deep environments of the Gulf. Yet, very little is known about hagfish life histories and ecology. I investigated inter and intraspecific variations in trophic structure of Eptatretus springeri, Eptatretus minor,...
Show moreHagfishes (Myxinidae) are common in deep waters of the Gulf of Mexico (GOM). Two of the species found in the GOM are endemic to the area and potentially provide key ecosystem services (e.g. generate substrate turnover and recycling of organic matter by consuming carrion falls) to the deep environments of the Gulf. Yet, very little is known about hagfish life histories and ecology. I investigated inter and intraspecific variations in trophic structure of Eptatretus springeri, Eptatretus minor, Myxine mcmillanae, including variations along relevant environmental gradients. At the time of this study, the Gulf of Mexico had recently experienced an environmental disaster with the Deep Water Horizon (DWH) oil spill. As a result, I also investigated the potential effects of the DWH oil spill on hagfish trophic structure, and the potential for higher bioaccumulation of mercury (Hg) in their muscle tissue. Feeding ecology and trophic structure were investigated using nitrogen (δ15N), carbon (δ13C) and sulfur (δ34S) stable isotopes and variability in the lipid content (Δδ13C) of each species was used as an indicator of periods of feeding and fasting. I was able to differentiate the isotopic niche of each of the species and determine the different feeding ecologies of E. springeri and M. mcmillanae. The isotopic niche of E. minor overlaps with that of E. springeri and M. mcmillanae. The most depleted mean δ15N values were observed in E. springeri (12.8‰), followed by E. minor (13.9 ‰) and M. mcmillanae (14.9‰). Eptatretus springeri had the highest (Δδ13C), lowest trophic level (δ15N) and exhibited the most isotopic variation with depth. This could suggest this species is an active predator that feeds regularly, and potentially relies on scavenging only to supplement its diet. Eptatretus minor had slightly higher Δδ13C, intermediate but depleted δ15N, and higher δ15N isotopic diversity. These characteristics suggest a more opportunistic foraging behavior for this species, potentially feeding on prey items from several trophic levels. Myxine mcmillanae had the highest δ15N but lowest Δδ13C, and no variation in δ15N with depth. These trends indicate this species could be experiencing irregular feeding with periods of fasting, potentially due to a mostly scavenging behavior and occasionally feeding on larger but infrequently available carrion falls of large animals. Spatial analysis showed all hagfish species displayed enriched δ15N and δ13C, and depleted δ34S values on the continental slope off Louisiana than along the North Florida Slope and in DeSoto Canyon. These shifts in isotopic signatures could be attributed to influx from riverine sources from the Mississippi River. Temporal variations were also correlated to the seasonality of nutrient discharge from the river. Isotopic shifts seemed to be a consequence of riverine inputs rather than as a result of changing environmental conditions from the DWH oil spill. This study also determined Total Hg (THg) and Hg species (Methyl-Mercury-MeHg, inorganic Hg-IHg) concentrations in hafish muscle tissue. There was significant intra and interspecific variation in THg concentrations of all three hagfish species. Enriched δ15N and much higher THg concentrations were observed in M. mcmillanae (11.9 ppm) when compared to E. minor (2.1 ppm) and E. springeri (1.1 ppm). Mean MeHg concentrations were highest in M. mcmillanae (10.9 ppm), followed by E. minor (1.4 ppm) and E. springeri (0.8 ppm), while mean IHg concentrations were 1.3 ppm, 0.7 ppm, and 0.4 ppm , respectively. However, Hg species displayed a wide range of variation, with IHg concentrations in muscle tissue accounting for up to 75% to 95% of the THg content for some individuals. THg concentrations were studied in relation to several biological and environmental factors (stable isotopes, depth, total, length, body weight and lipid content, spatial and temporal variations) but most of these relationships were not significant for one or more species, which suggests that more than one uptake and depuration pathway or factors could contribute to the bioaccumulation of Hg in hagfishes.
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Date Issued: 2016
Identifier: FSU_2016SP_Mickle_fsu_0071N_13275
Format: Thesis

Title: The Development of Forecast Confidence Measures Using NCEP Ensembles.
Creator: Durante, Andrew Vincent, Hart, Robert, Fuelberg, Henry, Krishnamurti, T.N., Watson, Andrew I., Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Ensemble model data can provide a wealth of guidance to forecasters, especially in terms of forecast confidence. A model run where members diverge generally corresponds to a low confidence forecast, while a model run where members converge generally corresponds to a forecast of high confidence. The current NWS graphically based forecasts accessible to the public do not show this measure of uncertainty and thus communicate a false sense of confidence or precision. From August 2004 into 2006,...
Show moreEnsemble model data can provide a wealth of guidance to forecasters, especially in terms of forecast confidence. A model run where members diverge generally corresponds to a low confidence forecast, while a model run where members converge generally corresponds to a forecast of high confidence. The current NWS graphically based forecasts accessible to the public do not show this measure of uncertainty and thus communicate a false sense of confidence or precision. From August 2004 into 2006, approximately 2 years of individual GFS model ensemble data were analyzed. The result is a climatology of each ensemble member, which obviously does not match the observed climatology based on the NCEP reanalysis. The GFS model ensemble climatology was normalized so that there is a mapping between the current model ensemble value and the climatological value. Since there is only two years of data, the climatology is calculated on a 45 day temporal window. This method is similar, but more simplistic, to the method that is used in the FSU Superensemble (Krishnamurti 2000) of using temporal windows to increase climatology robustness in the training dataset. The variables analyzed here include 2-m temperature, 10-m wind speed and 10-m vorticity. Normalized climatology distributions have been calculated for each grid point within the ensemble member, with forecast confidence measures developed by comparing the normalized spread of the ensemble members to the model climatological spread, as described below. This normalized spread is compared to the typical spread for that time of year, location, and forecast length to arrive at a relative measure of forecast uncertainty. If the current model uncertainty is greater (less) than the uncertainty of the model climatology, then there is a lower (higher) than average confidence. Confidence graphics have been developed and analyses to see how confidence values behave with certain synoptic situations are ongoing. This overall behavior along with certain case studies will be featured. It has also been seen that there is a statistical significant difference in NWS forecast error between low confidence and high confidence regimes. Average NWS error for the below (above) normal GFS confidence forecasts was 5.20oF (3.08oF). A student t-test on these values revealed that there is a statistically significant difference to 95% confidence of the mean forecast error during low and high confidence GFS forecasts. That is, the mean WFO forecast error is significantly increased during times of low forecast confidence in the GFS ensemble. Therefore, forecasters have a-priori knowledge of the likely human forecast error when they see the GFS ensemble output-- before the NWS forecast even verifies. During cases of extreme low confidence where the current model standard deviation is greater than the 25-year observational standard deviation, a climatology forecast was found to be more accurate than the overall ensemble mean. Although the confidence graphics are only based on the GFS ensembles as of now, more models will be added in the future to see how they behave when compared to each other. The GFS ensembles and the corresponding confidence technique have been used in the FSU-MM5 to see how a mesoscale model affects the overall confidence for a specific case. Recent feedback from NWS employees suggests an additional development of confidence graphics based on the "poor man's ensemble", which is an ensemble of all the operational forecast models. Eventually these graphics of below and above average confidence may be implemented into the Graphical Forecast Editor (GFE) for use in the National Digital Forecast Database (NDFD).
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Date Issued: 2006
Identifier: FSU_migr_etd-0627
Format: Thesis

Title: Development of a Florida High-Resolution Multisensor Precipitation Dataset for 1996-2001 -- Quality Control and Verification.
Creator: Marzen, Joseph Lee, Fuelberg, Henry E., Ruscher, Paul H., Ahlquist, Jon E., Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: The need for a high-resolution precipitation database over Florida is evident by the ever-increasing impact of water resources on society. The Multisensor Precipitation Estimator (MPE) software was developed by the National Weather Service to combine hourly rain gauge- and radar-derived precipitation estimates optimally. The MPE procedure creates hourly rainfall estimates on a 4 x 4 km&178; grid. This research uses the final product from the MPE procedure (MMOSAIC) to create a high-resolution...
Show moreThe need for a high-resolution precipitation database over Florida is evident by the ever-increasing impact of water resources on society. The Multisensor Precipitation Estimator (MPE) software was developed by the National Weather Service to combine hourly rain gauge- and radar-derived precipitation estimates optimally. The MPE procedure creates hourly rainfall estimates on a 4 x 4 km&178; grid. This research uses the final product from the MPE procedure (MMOSAIC) to create a high-resolution rainfall climatology over the Florida peninsula from 1996 through 2001. An objective rain gauge quality control (QC) procedure is developed to minimize the amount of erroneous gauge data that is input to the MPE procedure. This objective scheme compares the gauge data with corresponding raw radar data. A rigorous examination of rain gauge data and the encompassing radar-derived rainfall estimates revealed four main scenarios that are included in the QC procedure. The scenario responsible for removing the most data occurs when a radar-derived estimate reports heavy rainfall (> 1 in./h), while the gauge within that radar grid cell reports a value near zero. The QC procedure removes most of these suspect gauge data, thereby limiting their corrupting effect on the bias calculations within the MPE procedure. The other three QC scenarios removed a smaller number of gauges that would have adversely affected the calculations. 1 in./h), while the gauge within that radar grid cell reports a value near zero. The QC procedure removes most of these suspect gauge data, thereby limiting their corrupting effect on the bias calculations within the MPE procedure. The other three QC scenarios removed a smaller number of gauges that would have adversely affected the calculations. An analysis of the different rainfall products produced by MPE demonstrates the positive impact of the extensive quality control efforts. An independent set of rain gauges is used to evaluate the MPE products statistically for selected periods during 1999 and 2001. Results show that the final MPE product (MMOSAIC) outperforms both the radar and gauge data alone. Gauges alone generally cannot accurately represent the spatial details of warm season convective type precipitation events. Conversely, radar data depict convective precipitation events quite well; however, radars do a poor job of detecting cold season stratiform precipitation events. Analyses reveal that the MMOSAIC product utilizes the strengths of the gauges and the radars in an optimum way. Seasonal case studies comparing the independent set of gauge observations to the final MPE product show that there is good agreement between the two hourly sources (i.e., biases &61; -0.004 in., r &61; 0.78, and RMSD &61; 0.12 in.). Agreements are found to improve over daily and monthly accumulation periods. Results of this study describe the problems and uncertainties associated with quantitatively measuring Florida rainfall through a multisensor analysis
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Date Issued: 2004
Identifier: FSU_migr_etd-2681
Format: Thesis

Title: Detrital Zircon Dating of the Kodiak Accretionary Complex; South Alaska.
Creator: Mahjoor, Amir Sasan, Farris, David, Tull, James F., Odom, A. Leroy, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Southern Alaska crustal exposures provide an excellent opportunity to study the growth of collisional continental margins through the processes of terrane accretion, magmatism, accretionary prism development, and subduction of oceanic spreading ridges. Kodiak Island is one of the world's best exposed accretionary complexes, and is characterized by transport along dominant large-magnitude strike-slip faults of west North America and South Alaska. In this study we focus on detrital zircon...
Show moreSouthern Alaska crustal exposures provide an excellent opportunity to study the growth of collisional continental margins through the processes of terrane accretion, magmatism, accretionary prism development, and subduction of oceanic spreading ridges. Kodiak Island is one of the world's best exposed accretionary complexes, and is characterized by transport along dominant large-magnitude strike-slip faults of west North America and South Alaska. In this study we focus on detrital zircon dating of the Kodiak accretionary complex on Kodiak Island Alaska. Accretionary complexes are an important fundamental element of convergent plate margins and are also important structures in continental crust formation. Their presence in the geologic record is an indicator of past subduction zones. Six graywacke detrital zircon samples from the Kodiak and the Ghost Rocks Formations were analyzed using U/Pb dating of single crystals via laser-ablation inductively coupled plasma mass spectroscopy. The maximum depositional age of the three major formations are as follow: Kodiak Formation 56.2-69.2 Ma, and Ghost Rock 58.5 Ma. The age for the small outcrop of Narrow Cape Formation is 54.1. Kodiak and Ghost Rock Formation detrital zircon age are consistent with fossil ages of these two formations, but the fossil content of Narrow Cape is younger than the detrital zircon age we measured for this formation. Some evidence in our data like resurrection of certain age zircon grains between the accreted sequences, age gaps between the accreted sequences, different rate of sedimentation and etc. are evidenc for episodical accretion in the complex and also displacement of the accreted units along the west North America and Alaska right lateral large magnitude strike slip faults.
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Date Issued: 2011
Identifier: FSU_migr_etd-2788
Format: Thesis

Title: Determination of the Quantity of Cloud Liquid in Snow Clouds and Its Effect on Masking the Snow Scattering Signature.
Creator: Smith, John Robert, Liu, Guosheng, Bourassa, Mark, Fuelberg, Henry, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Many studies have been conducted on the satellite remote sensing of rainfall, but not on the remote sensing of snowfall. To obtain a global view of snowfall in a timely matter, passive high frequency microwave satellite measurements must be used. Therefore, an accurate algorithm for detecting and retrieving snowfall on a global scale is needed. In developing this algorithm, it is important to account for the snow scattering signature which reduces the upwelling emission signal from the ocean...
Show moreMany studies have been conducted on the satellite remote sensing of rainfall, but not on the remote sensing of snowfall. To obtain a global view of snowfall in a timely matter, passive high frequency microwave satellite measurements must be used. Therefore, an accurate algorithm for detecting and retrieving snowfall on a global scale is needed. In developing this algorithm, it is important to account for the snow scattering signature which reduces the upwelling emission signal from the ocean surface observed at the top of the atmosphere. However, the emission due to cloud liquid will increase the upwelling radiation, therefore masking the snow scattering signature. Thus, cloud liquid within snow clouds must be understood. In this study, data from the Cloud Profiling Radar on CloudSat and AMSR-E on Aqua are used to investigate the quantity of cloud liquid for snowfall events. The relationship between cloud liquid and echo top, cloud thickness, and two-meter air temperature is determined. The quantity of cloud liquid present in stratiform and convective snowfall events is also compared. Using snowfall profiles obtained from the reflectivity profiles provided by CloudSat, the masking effect of cloud liquid on the snow scattering signature on vertical and horizontal brightness temperature is determined for snow events with various surface snowfall rates. The masking effect on a parameter designed to reduce the emission signal due to cloud liquid, the polarization corrected temperature, is also tested.
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Date Issued: 2010
Identifier: FSU_migr_etd-0369
Format: Thesis

Title: A Marine-Influenced Siliciclastic Unit (Citronelle Formation) in Western Panhandle Florida.
Creator: Means, Guy H., Wise, Sherwood W., Arnold, Anthony J., Donoghue, Joseph F., Kish, Stephen J., Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: The Citronelle Formation is the most widely occurring, surficial geologic unit along the northeast Gulf of Mexico. It is a siliciclastic unit consisting primarily of sands and gravels with varying amounts of clay and minor amounts of mica and heavy minerals. Historically, the unit has been thought to be a fluvial deposit of Pliocene age. Evidence presented here suggests, at least in part, a marine origin. In some pits and exposures in southern Walton and Okaloosa Counties in western Florida,...
Show moreThe Citronelle Formation is the most widely occurring, surficial geologic unit along the northeast Gulf of Mexico. It is a siliciclastic unit consisting primarily of sands and gravels with varying amounts of clay and minor amounts of mica and heavy minerals. Historically, the unit has been thought to be a fluvial deposit of Pliocene age. Evidence presented here suggests, at least in part, a marine origin. In some pits and exposures in southern Walton and Okaloosa Counties in western Florida, sediments that are referred to the Citronelle Formation contain well preserved Ophiomorpha, bivalve mollusk casts, shark teeth, terrestrial vertebrate fossils and other trace fossil remains. Various types of bedding, including cross bedding, occur. These apparent nearshore marine depositional facies are the focus of this investigation which will attempt to determine the paleo- environmental depositional regimes, age, and how this facies relates to the Cirtonelle Formation. Field work was conducted and data were gathered from exposures and outcrops within the study area. Stratigraphic sections were measured and described. Where feasible, sediment samples were collected for sieve analysis. Further sampling of trace fossils (Ophiomorpha) and body fossils was conducted for analysis. Cross-bedding orientation was recorded from one locality to determine predominant paleo-current direction. These data, when combined, support the hypothesis that these sediments that have been mapped as Citronelle Formation represent nearshore, marine facies. However, their placement in the Citronelle Formation still remains questionable due to the lithologic similarity of overlying and underlying units.
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Date Issued: 2009
Identifier: FSU_migr_etd-2508
Format: Thesis

Title: A Numerical Investigation of the Impact of Ice Hydrometeors on the Intensity of Hurricane Isabel.
Creator: Sheermohamed, Jordanna, Krishnamurti, T. N., Hart, Robert, Clayson, Carol Anne, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: The goal of this study is to further investigate the relationship between the microphysical processes of a tropical cyclone and its intensification. Hydrometeors such as rainwater, cloud ice, cloud water, snow, and graupel play a significant role updraft and downdraft characteristics, precipitation, evaporation, ice concentration, and the distribution of latent heat. These processes are the primary heat sources for tropical cyclones. Therefore, it is expected that cloud microphysics may...
Show moreThe goal of this study is to further investigate the relationship between the microphysical processes of a tropical cyclone and its intensification. Hydrometeors such as rainwater, cloud ice, cloud water, snow, and graupel play a significant role updraft and downdraft characteristics, precipitation, evaporation, ice concentration, and the distribution of latent heat. These processes are the primary heat sources for tropical cyclones. Therefore, it is expected that cloud microphysics may directly or indirectly influence the intensity of the hurricane. The first objective of this study is to evaluate the impact of different sophisticated explicit cloud microphysics parameterization schemes available in the PSU/NCAR MM5 model, on the hurricane forecast. Of the four microphysical parameterization schemes, the one that exhibited an intensity pattern closely resembling that of the observed values for the hurricane was selected in order to continue onto the next phase of the project. The second objective is to assess the impact of ice hydrometeors (cloud ice), in the overall performance of the hurricane forecast. This phase further investigates the impact of the selected microphysical processes on the overall forecast of the hurricane, with an emphasis on intensity. This is achieved by suppressing some of the microphysical processes that would allow for ice depletion. By doing so, we indirectly increase the amount of ice in the hurricane. This numerical comparison is done in the selected scheme both before and after ice production terms are modified, in order to substantiate the hypothesis whether or not an increased amount of ice in a tropical cyclone would lead to a more intense storm.
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Date Issued: 2005
Identifier: FSU_migr_etd-1782
Format: Thesis

Title: A Numerical Analysis of the First-Order Closure for Synoptic Eddy and Low-Frequency Flow (Self)-Feedback.
Creator: Lin, Lin, Jin, Feifei, N.Krishnamurti, T., Ellingson, Robert G., Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: The two-way interaction between synoptic eddy and low-frequency flow (SELF), has been recognized to be important for the low-frequency variability of the atmosphere circulation. By considering a stochastic basic flow that captures the observed synoptic eddy statistics, we obtained both first and higher order approximations for a linear closure for the SELF feedback. The validity of the first order approximation depends on the intensity of the eddy variance. The first order approximation...
Show moreThe two-way interaction between synoptic eddy and low-frequency flow (SELF), has been recognized to be important for the low-frequency variability of the atmosphere circulation. By considering a stochastic basic flow that captures the observed synoptic eddy statistics, we obtained both first and higher order approximations for a linear closure for the SELF feedback. The validity of the first order approximation depends on the intensity of the eddy variance. The first order approximation breaks down only when the level of eddy variance is unrealistically large. Under observed level of the synoptic eddy variance, I demonstrated that the first-order approximation is largely as good as high order approximations. Direct numerical ensemble simulations of the linearized model with stochastic basic state also confirm the validity of the first order approximation. Moreover, forced solutions under idealized external forcing are analyzed to delineate the importance of the SELF feedback in generating the patterns of low-frequency modes.
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Date Issued: 2005
Identifier: FSU_migr_etd-1345
Format: Thesis

Title: North Atlantic Decadal Variability of Ocean Surface Fluxes.
Creator: Hughes, Paul J., Bourassa, Mark A., Kim, Kwang-Yul, Cai, Ming, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: The spatial and temporal variability of the surface turbulent heat fluxes over the North Atlantic is examined using the new objectively produced FSU3 monthly mean 1°x1° gridded wind and surface flux product for 1978-2003. The FSU3 product is constructed from in situ ship and buoy observations via a variational technique. A cost function based on weighted constraints is minimized in the process of determining the surface fluxes. The analysis focuses on a low frequency (basin wide) mode of...
Show moreThe spatial and temporal variability of the surface turbulent heat fluxes over the North Atlantic is examined using the new objectively produced FSU3 monthly mean 1°x1° gridded wind and surface flux product for 1978-2003. The FSU3 product is constructed from in situ ship and buoy observations via a variational technique. A cost function based on weighted constraints is minimized in the process of determining the surface fluxes. The analysis focuses on a low frequency (basin wide) mode of variability where the latent and sensible heat flux anomalies transition from mainly positive to negative values around 1998. It is hypothesized that the longer time scale variability is linked to changes in the large scale circulation patterns possibly associated with the Atlantic Multidecadal Oscillation (AMO; Schlesinger and Ramankutty 1994, Kerr 2000). The changes in the surface heat fluxes are forced by fluctuations in the mean wind speed. Zonal averages show a clear dissimilarity between the turbulent heat fluxes and wind speed for 1982-1997 and 1998-2003 over the region extending from the equator to roughly 40°N. Larger values are associated with the earlier time period, coinciding with a cool phase of the AMO. The separation between the two time periods is much less evident for the humidity and air/sea temperature differences. The largest differences in the latent heat fluxes, between the two time periods, occur over the tropical, Gulf Stream, and higher latitude regions of the North Atlantic, with magnitudes exceeding 15 Wm-2. The largest sensible heat flux differences are limited to areas along the New England coast and poleward of 40°N.
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Date Issued: 2006
Identifier: FSU_migr_etd-3672
Format: Thesis

Title: Network Analysis of Hurricanes Affecting the United States.
Creator: Fogarty, Emily A., Elsner, James B., Hart, Robert, Stallins, J. A., Jagger, Thomas, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Hurricanes affecting the United States cause severe damage and kill people. The risk of future hurricane activity along the coast is the subject of much scientific and public interest. While considerable work had been done to understand the occurrence of hurricanes along the coast, much less has been done to examine the inter-relationships among the hurricanes. This dissertation concerns the relationships of hurricanes affecting the United States using methods of network analysis. Network...
Show moreHurricanes affecting the United States cause severe damage and kill people. The risk of future hurricane activity along the coast is the subject of much scientific and public interest. While considerable work had been done to understand the occurrence of hurricanes along the coast, much less has been done to examine the inter-relationships among the hurricanes. This dissertation concerns the relationships of hurricanes affecting the United States using methods of network analysis. Network analysis has been used in a variety of fields to study relational data, but has yet to be used in the study of hurricane climatology. The present work is largely expository introducing network analysis and showing how it can be applied to possibly better understanding regional hurricane activity as well as hurricane activity overtime. The research is divided into two cases. The first case consists of networks developed based on the relationships of spatial locations of landfalls and the second part consists of networks developed based on the relationships of the temporal occurrence of landfalls. In the first case, the network links coastal locations (termed nodes) with particular hurricanes (termed links). The topology of the network is examined using local and global metrics. Results show that certain regions of the coast (like Louisiana) have high hurricane occurrence rates, but not necessarily high values of network connectivity. Low values of connectivity indicate that hurricanes affecting Louisiana tend not to affect other regions. Regions with the highest values of connectivity include southwest Florida, northwest Florida, and North Carolina. Virginia which has a relatively low occurrence rate is well-positioned in the network having a relatively high value of betweenness. In the second case, the year-to-year variation in U.S. hurricane activity is examined by extending the ideas and concepts of network analysis for time series data. The "visibility" network link years experiencing a hurricane landfall with other hurricane landfall years ``visible" to each other through time. The topology of the visibility network is examined using local and global metrics. Results show that overall the visibility network has few years with many lines of visibility, therefore, many linkages to other years. Years with high hurricane count have more visibility in the network than those years that have less storms. Among years with high counts the years that are surrounded (before and after) with years of low counts will have greater visibility. The years 1886, 1893, 1955 and 2004 are highly visible in the network of U.S. hurricanes. A year is more central if it is a link in more visibility chains between other years in the network. Six conditional networks are constructed for the spatial and temporal networks based on years of below and above average values of important climate variables. Significant differences in the connectivity of the network are noted for different phases of the El Nino-Southern Oscillation. During El Nino years, when the equatorial waters of the eastern Pacific are warm, there tends to be shearing winds and subsidence over large portions of the North Atlantic where hurricanes form. These conditions lead to fewer hurricanes affecting the United States. More work is needed to better understand the details of how climate influences the network of landfalls. The scientific merit of the research is a better understanding of the relationships in the regional risk of hurricane activity. The broader impacts are an introduction of network analysis to hurricane climatology.
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Date Issued: 2009
Identifier: FSU_migr_etd-4430
Format: Thesis

Title: Physical Description and Analysis of the Variability of Salinity and Oxygen in Apalachicola Bay.
Creator: Mortenson, Eric, Speer, Kevin, Chicken, Eric, Dewar, William, Bourassa, Mark, Landing, William, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Apalachicola Bay is a shallow estuarine system enclosed by a chain of barrier islands on the west Florida shelf. It is important both ecologically and economically due to the high biological productivity in the bay. The bay is subject to fluctuations in salinity, temperature, and dissolved oxygen. Salinity fluctuations are beneficial to many organisms in the bay. Measurements in and around the bay are analyzed to give a general description of how the bay's hydrographic properties vary in...
Show moreApalachicola Bay is a shallow estuarine system enclosed by a chain of barrier islands on the west Florida shelf. It is important both ecologically and economically due to the high biological productivity in the bay. The bay is subject to fluctuations in salinity, temperature, and dissolved oxygen. Salinity fluctuations are beneficial to many organisms in the bay. Measurements in and around the bay are analyzed to give a general description of how the bay's hydrographic properties vary in space and time. A salinity model using conservation of mass and salt is constructed in order to describe how the bay's salinity changes due to various forcing mechanisms. The main factors affecting salinity in Apalachicola Bay are freshwater inflow from Apalachicola River, winds in the direction of the major axis of the bay, and to a lesser extent, tides. When smoothed with a ten day filter, the salt model results over the three year study period agree with observations in each side of the bay at a correlation between 0.8 and 0.9. Variations in the concentration of dissolved oxygen with time are also analyzed, and the processes driving these are wind speed, temperature, biological activity, and advection. During one period when tides affect the concentration of dissolved oxygen, a regressive model based on tidal velocity and light measured near the bottom agree with observation at a correlation of > 0.8.
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Date Issued: 2013
Identifier: FSU_migr_etd-7519
Format: Thesis

Title: Polarization Signature in Micro-Wave Humidity Sounder Window Channels.
Creator: Chen, Xu, Zou, Xiaolei, Ellingson, Robert G., Liu, Guosheng, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Microwave Humidity Sounders (MHS) onboard NOAA-15, -16, -17, -18, -19 and EUMETSAT MetOp-A, -B provide radiance measurements at a single polarization state at any of the five observed frequencies. Microwave Humidity Sounder (MWHS) onboard FengYun-3 (FY-3) satellite has a unique instrument design and provides dual polarization measurements at 150 GHz. In this study, the MWHS polarization signal is investigated using observed and modeled data. It is shown that the quasi-polarization brightness...
Show moreMicrowave Humidity Sounders (MHS) onboard NOAA-15, -16, -17, -18, -19 and EUMETSAT MetOp-A, -B provide radiance measurements at a single polarization state at any of the five observed frequencies. Microwave Humidity Sounder (MWHS) onboard FengYun-3 (FY-3) satellite has a unique instrument design and provides dual polarization measurements at 150 GHz. In this study, the MWHS polarization signal is investigated using observed and modeled data. It is shown that the quasi-polarization brightness temperatures at 150 GHz display a scan angle dependent bias. Under calm ocean conditions, the polarization difference at 150 GHz becomes non-negligible when the scan angle varies from 10 to 45 degrees and reaches a maximum when the scan angle is about 30 degrees. Also, the polarization state is sensitive to surface parameters such as surface wind speed. Under clear-sky conditions, the differences between horizontal and vertical polarization states at 150 GHz increase with decreasing surface wind speed. Therefore, the polarization signals from the cross-track scanning microwave measurements at window channels contain useful information of surface parameters. What is more, cloud liquid water is also proved to be a non-ignorable factor reducing the difference between horizontal and vertical polarization states at 150 GHz. Also, the availability of dual polarization measurements allows a one-to-one conversion from the antenna brightness temperature to sensor brightness temperature if there exit a cross-polarization spill-over.
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Date Issued: 2014
Identifier: FSU_migr_etd-8755
Format: Thesis

Title: Pliocene-Pleistocene Calcareous Nannofossil Biostratigraphy of IODP Hole 1396C Adjacent to Montserrat Island in the Lesser Antilles, Caribbean Sea, Plus Experimentally Induced Diagenesis.
Creator: Aljahdali, Mohammed H., Wise, Sherwood W., Wang, Yang, Parker, William, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Integrated Ocean Drilling Program Hole 1396C, adjacent to Montserrat Island, provides a lower Pliocene to Pleistocene record of calcareous nannofossil assemblages (CN11 to CN15). The nannofossil assemblages are generally common to abundant with moderate preservation in the upper Pleistocene, and very abundant with good preservation in the lower Pleistocene and the Pliocene. The sequence was zoned via the Gartner (1977) scheme for the Pleistocene and the Okada and Bukry (1980) zonation for the...
Show moreIntegrated Ocean Drilling Program Hole 1396C, adjacent to Montserrat Island, provides a lower Pliocene to Pleistocene record of calcareous nannofossil assemblages (CN11 to CN15). The nannofossil assemblages are generally common to abundant with moderate preservation in the upper Pleistocene, and very abundant with good preservation in the lower Pleistocene and the Pliocene. The sequence was zoned via the Gartner (1977) scheme for the Pleistocene and the Okada and Bukry (1980) zonation for the Pliocene using the recent age updates from Backman et al. (2012). Sedimentation rates inferred by nannofossil biostratigraphy suggest low sedimentation rates in the Pleistocene and high sedimentation rates during the Pliocene. This sedimentation pattern was also observed at Site 1000 from Ocean Drilling Program Leg 165 in the central Caribbean Sea, suggesting a regional event caused by the closure of the Central American seaway. During the expedition (IODP, Expedition 340), selected samples from Holes 1396A and C were used to determine the sediment water content by heating them at 105°C at room pressure for 24 hours. This process produced an artificial "late diagenesis" effect with severe overgrowth features on the nannofossils. Further examination of the diagenetic progression in these samples should provide a better understanding of the progression of carbonate diagenesis in cases of high temperatures and pressures.
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Date Issued: 2013
Identifier: FSU_migr_etd-7270
Format: Thesis

Title: Pleistocene Calcareous Nannofossil Biostratigraphy of Site U1352, Canterbury Basin, New Zealand.
Creator: Myers, Nicholas R., Wise, Sherwood W., Parker, William, Wang, Yang, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: During IODP Leg 317 off the east coast of New Zealand, three continental shelf sites (U1351, U1353 and U1354) and one continental slope site were cored. Sedimentary sequences representing shallow water depositional cycles were recovered and ranged from Upper Miocene to recent in age. One of the most widely used tools in the academic and scientific realm by onboard paleontologists to quickly determine such ages, along with foraminifera, are calcareous nannofossils. Adequate ages are highly...
Show moreDuring IODP Leg 317 off the east coast of New Zealand, three continental shelf sites (U1351, U1353 and U1354) and one continental slope site were cored. Sedimentary sequences representing shallow water depositional cycles were recovered and ranged from Upper Miocene to recent in age. One of the most widely used tools in the academic and scientific realm by onboard paleontologists to quickly determine such ages, along with foraminifera, are calcareous nannofossils. Adequate ages are highly dependent on the amount of time the shipboard paleontologist has to scan samples for biozone markers, and in some instances, zonal markers are unable to be found. Therefore, it is sometimes necessary for a secondary, post-cruise analysis of sediments to confirm the biostratigraphy developed during the cruise. Secondary objectives for this project include development of calcareous nannofossil abundance counts to analyze population dynamics, richness, evenness, and diversity as well as examination of ages and abundances of reworked and transported nannofossil assemblages in order to better understand transport mechanisms and sediment sourcing of the area. This additional onshore post-cruise analysis will allow for a more detailed study of the biozonation of the region as well as general assemblages. It is also believed that nannofossil abundances/assemblages undergo a profound change across sequence stratigraphic boundaries. This work aims to analyze these changes and determine the feasibility of using nannofossils to study these depositional cycles. Simple smear-slides have been prepared from ~100 samples and are currently undergoing semi-quantitative analysis using an Axioscope II light microscope. Shipboard biostratigraphic analysis of calcareous nannoplankton is crucial for accurate determination of stratigraphic ages due to their diversity, rapid evolution/mutation, and abundance in marine sediments. Establishing good age control allows for correlation with other proxies to develop precise chronology of cored sediments.
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Date Issued: 2013
Identifier: FSU_migr_etd-7523
Format: Thesis

Title: Modeling Snow Aggregates and Their Single Scattering Properties: Implications to Snowfall Remote Sensing.
Creator: Nowell, Holly Kreutzer, Liu, Guosheng, Ellingson, Robert G., Ruscher, Paul, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Ice and snow particles have a great, yet poorly understood impact on the Earth's climate system. One of the difficulties of studying snow particles is their irregular shape. While spheres and even oblate spheroids backscatter radiation in a consistent manner, irregularly shaped objects do not. Due to the complexities of snowflakes, they are often assumed to be spherical for both satellite retrieval and modeling purposes. This can introduce error in many studies. While there are several...
Show moreIce and snow particles have a great, yet poorly understood impact on the Earth's climate system. One of the difficulties of studying snow particles is their irregular shape. While spheres and even oblate spheroids backscatter radiation in a consistent manner, irregularly shaped objects do not. Due to the complexities of snowflakes, they are often assumed to be spherical for both satellite retrieval and modeling purposes. This can introduce error in many studies. While there are several aggregate snowflake models in existence, many use spheres as a building block for the snowflake. This is inaccurate as most snowflakes are comprised of a combination of bullet rosettes, plates, columns, and dendritic snow crystals. Furthermore, most studies do not have constraints in place to make sure that snowflakes are of the correct size and density as observed from field studies. None of the theoretical models examined in this study analyze the single-scattering properties of the flakes. In order to improve upon previous models, this study creates an aggregate snowflake using 200 ìm and 400 ìm 6-bullet rosette crystals. These crystals and resultant flakes are required to follow established size-density relationships obtained from numerous field studies. In addition, the flakes must also be of similar fractal dimension determined from other case studies. The single-scattering properties of these flakes are then determined from the discrete dipole approximation.
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Date Issued: 2010
Identifier: FSU_migr_etd-2511
Format: Thesis

Title: Modeling Groundwater Flow in Karst Aquifers: An Evaluation of MODFLOW-CFP at the Laboratory and Sub-Regional Scales.
Creator: Gallegos, Josue Jacob, Hu, Bill X., Ye, Ming, Kish, Stephen, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: A karst aquifer is a carbonate aquifer where groundwater flow dominantly occurs through bedding planes, fractures, conduits, and caves created by and/or enlarged by dissolution. Conventional groundwater modeling methods assume that groundwater flow can be described by Darcian principles where primary porosity (i.e. matrix porosity) and laminar flow are dominant in the aquifer. However, in karst aquifers this assumption is inapplicable due to the dual porosity present in karst aquifers. While...
Show moreA karst aquifer is a carbonate aquifer where groundwater flow dominantly occurs through bedding planes, fractures, conduits, and caves created by and/or enlarged by dissolution. Conventional groundwater modeling methods assume that groundwater flow can be described by Darcian principles where primary porosity (i.e. matrix porosity) and laminar flow are dominant in the aquifer. However, in karst aquifers this assumption is inapplicable due to the dual porosity present in karst aquifers. While Darcian principles may apply to the matrix portion of the karst aquifer, they often do not apply to flow through conduits, where flow velocities can be great enough to invalidate the applicability of Darcy's Law. Thus, different methodologies must be used to model groundwater flow in karst aquifers. MODFLOW-CFP is a relatively new modeling program which accounts for turbulent and laminar flow in pipe like karst caves. In this study the methodology of MODFLOW-CFP is compared to several other methods to evaluate the accuracy that CFP can achieve when modeling flow in karst conditions at a laboratory and sub-regional scale. This study also briefly evaluates the program MT3DMS, to test its abilities for modeling contaminant transport in a karst aquifer analog at a laboratory scale. Results at the laboratory scale indicate that CFP is more accurate when compared to simulated results generated by MODFLOW 2005, and performs better when compared to a Navier-Stokes finite element model developed by Hua (2009). At the sub-regional scale, CFP is less accurate than the traditional MODFLOW-2000 model when comparing peak flow conditions for a simulated storm event. However, for total simulated flow for the storm event, CFP produces more accurate results than MODFLOW-2000. Regarding transport, MT3DMS can adequately simulate transport within karst at a laboratory scale.
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Date Issued: 2011
Identifier: FSU_migr_etd-4377
Format: Thesis

Title: Modeled Diurnally Varying Sea Surface Temperatures and Their Influence on Surface Heat Fluxes.
Creator: Weihs, Rachel Rebecca, Bourassa, Mark, Misra, Vasubandhu, Sura, Phillip, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: A diurnal warming model is used create a new data set of global, diurnally varying sea surface temperatures over a five year period from 2000 to 2004. The model is forced with atmospheric bulk variables, precipitation rate, and radiation fluxes from NASA's MERRA reanalysis whereas bulk SST is approximated by the Reynolds OI AVHRR-only SST dataset. The model simulates the diurnal warming magnitude (dSST) and sensible heat flux and latent heat flux computed with and without a diurnally varying...
Show moreA diurnal warming model is used create a new data set of global, diurnally varying sea surface temperatures over a five year period from 2000 to 2004. The model is forced with atmospheric bulk variables, precipitation rate, and radiation fluxes from NASA's MERRA reanalysis whereas bulk SST is approximated by the Reynolds OI AVHRR-only SST dataset. The model simulates the diurnal warming magnitude (dSST) and sensible heat flux and latent heat flux computed with and without a diurnally varying skin temperature at every hour for each day. Differences between each of the fluxes with and without a diurnally varying SST are examined. Characteristics of the dataset are identified on a daily and semi-seasonal scale over the globe. Diurnal warming is concentrated in areas with climatologically low surface wind speed regimes, for example, in the low level convergence zones of the tropics, the Indian Ocean as a result from the Asian monsoon wind variability, the Mediterranean Sea in the summer months, the central Pacific coastlines near mountain ranges in the early months of the year, and the mid-Atlantic in association with the Bermuda High. Maximum averaged diurnal warming reaches roughly 0.3˚C and latent heat flux deficits of 15 W/m2 particularly in the Indian Ocean over a two-month period. With the exception of persistent diurnal warming in the central tropical Pacific just south of central Mexico, the duration of diurnal warming as a percentage of total daylight hours between the tropics and midlatitudes is quite comparable. In the mid-Atlantic, dSSTs can exceed roughly 0.7˚C up to 25% of the time in the two month period. Similarly, latent heat fluxes are underestimated by at least 10 W/m2 up to 25% of the time. Sensitivity of diurnal warming is specific to particular ranges of low wind speed and large solar radiation. Best guess bias corrections to the MERRA wind speeds results in increases as large as 1.5°C. Bimonthly averages, however, are generally less than 0.06°C and latent heat fluxes are less than 2 W/m2. While precipitation is the smallest contributor compared to winds and radiation, the model configurations allows conditions that are contrary to the underlying model physics in which precipitation increases diurnal warming.
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Date Issued: 2012
Identifier: FSU_migr_etd-5266
Format: Thesis

Title: Mixing Corrosion in a Coastal Aquifer.
Creator: Esterson, Kris, Cowart, James B., Lundberg, Neil S., Osmond, John K., Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: The coastal aquifer of the northeastern Yucatan peninsula is a mixing zone where freshwater from the platform interior mixes with seawater and saline groundwater to form new brackish solutions. The brackish solutions may form stable flows that move seaward through the aquifer as discrete water parcels. These flows frequently have lowered pH, may be undersaturated with respect to calcite, and may produce significant regional-scale porosity changes due to mixing corrosion.
Date Issued: 2003
Identifier: FSU_migr_etd-0504
Format: Thesis

Title: Modeling Streamflow Using Gauge-Only versus Multi-Sensor Rainfall.
Creator: Sullivan, John Lawrence, Fuelberg, Henry E., Ruscher, Paul H., Liu, Guosheng, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: This study evaluates the impacts of two types of rainfall input on simulated streamflow using a specialized, fully-distributed hydrologic model—the Watershed Assessment Model (WAM). We compare gauge-only Thiessen polygon input data with the gridded 4 × 4 km Florida State University (FSU) version of the National Weather Service (NWS) Multi-sensor Precipitation Estimator (MPE) scheme. Streamflow results are compared to observed amounts over a six year period (2000-2005) at two U.S. Geological...
Show moreThis study evaluates the impacts of two types of rainfall input on simulated streamflow using a specialized, fully-distributed hydrologic model—the Watershed Assessment Model (WAM). We compare gauge-only Thiessen polygon input data with the gridded 4 × 4 km Florida State University (FSU) version of the National Weather Service (NWS) Multi-sensor Precipitation Estimator (MPE) scheme. Streamflow results are compared to observed amounts over a six year period (2000-2005) at two U.S. Geological Survey (USGS) stream gauge sites in the greater Florida Suwannee River basin. One catchment has an area of 1505 km2, while the smaller catchment is 500 km2. Previous comparisons have been made between the two different precipitation data types using mean areal precipitation calculations over several Florida basins. This study of streamflow expands on those findings. Results show significant differences in simulated streamflow when the higher-resolution FSU MPE rainfall data are input to WAM. However, the FSU MPE dataset does not always provide better results with this model configuration. The improvements in WAM simulated streamflow depend on a combination of factors, including the desired type of comparison with observed amounts (volume or correlation), rainfall pattern characteristics, and individual event scenarios. The accumulations of FSU MPE WAM streamflow generally are found to be more accurate than those from Thiessen polygons. During drought periods, MPE-derived streamflow provided more accurate accumulations, but coefficients of determination were not always improved. During years with more average rainfall events, FSU MPE produced greater underestimates of accumulation amounts, and thus a better approximation by the Thiessen polygon input. Seasonal results emphasized the weaknesses of each data source. Rain gauges usually are not able to capture the small scale spatial variability of summer rainfall events. And, radar-derived precipitation generally is underestimated during relatively low top stratiform winter events. When simulating streamflow with a hydrologic model using rain gauge input, it is apparent that gauge locations are very important. Generally speaking, increasing the spatial density of gauges will produce a better representation of rainfall. Our small basin was found to be prone to significant underestimates of accumulations and lower coefficients of determination regardless of the rainfall input. However, statistical differences between our larger and smaller basins are not as dramatic with the FSU MPE data. Current results are based on the WAM model as configured for this study. Results from other models and/or other configurations may be different. Although there appear to be errors in both WAM's ability to utilize the rainfall data properly and in the rainfall data measurements themselves, the results highlight areas where both can be improved.
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Date Issued: 2008
Identifier: FSU_migr_etd-0403
Format: Thesis

Title: Modified JMA ENSO Index and Its Improvements to ENSO Classification.
Creator: Keeling, Travis B., O’Brien, James J., Cunningham, Philip, Cai, Ming, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: El Nino-Southern Oscillation (ENSO) is a widely known phenomenon that affects many areas including the southeast United States. Over the southeast U.S. the Japan Meteorological Agency (JMA) ENSO index was modified to establish better classifications. In order to properly understand the effects of ENSO on this location a new approach was needed. Spatial resolution was improved by utilization of the PRISM dataset. PRISM provided monthly precipitation and temperature data over the contiguous US...
Show moreEl Nino-Southern Oscillation (ENSO) is a widely known phenomenon that affects many areas including the southeast United States. Over the southeast U.S. the Japan Meteorological Agency (JMA) ENSO index was modified to establish better classifications. In order to properly understand the effects of ENSO on this location a new approach was needed. Spatial resolution was improved by utilization of the PRISM dataset. PRISM provided monthly precipitation and temperature data over the contiguous US at 4 km resolution. Temporal resolution was improved by disregarding the traditional JMA definition of an ENSO year. The new definition requires six consecutive months of 0.5°C anomalies or larger to be listed as an ENSO event. By utilization of this definition, the ENSO index was modified to a monthly index from a yearly index. Many ENSO events begin in the summer months and end before the preceding September, therefore, an adoption of a monthly index is justified. Although several of the effects vary widely over the domain, there are a few prevalent patterns of ENSO effects. During warm phase, from November-April, wet conditions are seen in the coastal areas. July and August are both dry. From fall to spring, Florida and the Atlantic Coast are basically dry, however; the Mississippi River Valley doesn't appear wet as previous studies have indicted. Patterns of temperatures across the southeast are less variable than the precipitation. Differences between the ModJMA and JMA can be seen in several months, especially during late spring and early autumn. This result is not surprising based on the rigid definition of the JMA index. An interesting result presented itself throughout the study. Individual tropical storms can be identified with the increased resolution PRISM data provides. A state by state breakdown of the ModJMA conclusions provides regional summaries. The ModJMA better classifies ENSO periods and leads to a more precise impact of ENSO over the southeast United States.
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Date Issued: 2009
Identifier: FSU_migr_etd-3246
Format: Thesis

Title: Molecular Characterization of a Microbial Community from Uranium-Contaminated Acidic Sediment.
Creator: North, Nadia, Balkwill, David, Kostka, Joel, Marcus, Nancy, Dollhopf, Sherry, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: The Field Research Center (FRC) in Oak Ridge, TN, was established by the U.S. Department of Energy's Natural and Accelerated Bioremediation Research (NABIR) Program to develop strategies for bioremediation of contaminant metals and radionuclides. The FRC is centered on groundwater plumes that originate from former S-3 Waste Disposal Ponds located at the Y-12 Plant where acidic nitrate- and uranium-contaminated waste was disposed. The groundwater and sediment surrounding this area are in need...
Show moreThe Field Research Center (FRC) in Oak Ridge, TN, was established by the U.S. Department of Energy's Natural and Accelerated Bioremediation Research (NABIR) Program to develop strategies for bioremediation of contaminant metals and radionuclides. The FRC is centered on groundwater plumes that originate from former S-3 Waste Disposal Ponds located at the Y-12 Plant where acidic nitrate- and uranium-contaminated waste was disposed. The groundwater and sediment surrounding this area are in need of remediation. To test the bioremediation potential of microorganisms in the contaminated FRC sediment, Fe(III)-reducing bacteria (FeRB) were enriched for, as they represent indigenous microorganisms capable of immobilizing uranium in situ. DNA was extracted from more than 20 Fe(III)-reducing enrichment cultures at both neutral and low pH. Through cloning and sequencing of 16S rRNA genes, considerable differences in phylotypes found in Fe(III)-reducing enrichments from background and contaminated FRC sediment were discovered. In the background Fe(III)- reducing enrichments (pH 7), over two-thirds of the 16S rRNA gene sequences obtained were closely related to members of the Geobacteraceae family. The cultivated isolates from this family are capable of Fe(III)-reduction, and are commonly found in sedimentary environments. However, sediment from the contaminated neutrophilic Fe(III)-reducing enrichments revealed that almost half of the 16S rRNA gene sequences were 96% similar to the newly described Fe(III)-reducing species Anaeromyxobacter dehalogenans, but no Geobacteraceae sequences were detected. In Fe(III)-reducing enrichments cultured at low pH (4 to 5), only 16S rRNA gene sequences closely related to Gram positive organisms were detected. From the contaminated sediment enrichment cultures at low pH, the most predominant 16S rRNA gene sequences retrieved were closely related to Gram positive organisms Brevibacillus and Paenibacillus. T-RFLP analysis of enrichment cultures strongly supported the sequencing results. Following the experiments with Fe(III)-reducing enrichment cultures, cultivation-independent studies were conducted using a quantitative method. Quantitative molecular techniques provided a direct determination of the abundance of selected groups of FeRB before and after sediment biostimulation. Using DNA extracted directly from the sediment, MPN-PCR was conducted to quantify the differences in abundance of Geobacter-, Anaeromyxobacter-, Paenibacillus-, and Brevibacillus- type sequences using primer sets specifically designed for these groups. The only sequences that increased in abundance after biostimulation were Geobacter-type 16S rRNA gene sequences. To account for other groups of stimulated organisms, cloning and sequencing was conducted in parallel with the quantitative PCR experiments. A large diversity of microorganisms from FRC sediment were revealed, including species from alpha, beta, delta, and gamma subdivisions of the Proteobacteria, as well as low and high G+C Gram positive species. Phylogenies suggesting certain physiologies, such as nitrate reduction, metal reduction, dechlorination, and degradation of metal-chelator complexes and fuel hydrocarbons were identified. Obvious trends in 16S rRNA gene sequences following the biostimulation of FRC sediments included an increase in sequences within the delta Proteobacteria, as well as the maintenance of a large abundance of sequences within the genus Methylobacterium, in the alpha Proteobacteria. Due to the diversity of organisms detected after biostimulation of contaminated sediments, we suggest that new model organisms should be pursued to aid in the ongoing development of bioremediation strategies for uranium contamination.
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Date Issued: 2003
Identifier: FSU_migr_etd-2544
Format: Thesis

Title: Microwave Radiative Transfer Modeling of Ice in the Atmosphere: A Critical Examination of Cloud Ice Utilizing Remote Sensing.
Creator: Zuiderweg, Adriaan T., Liu, Guosheng, Ruscher, Paul, Kim, KwangYul, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Tropospheric cloud ice has a significant impact on the earth's radiative balance and climate, and to help improve the ability to forecast short-term through climatological-scale weather, the importance of quantification of these ice particles is not to be underestimated. To that end, the study presented here describes an attempt to accomplish large spatial-scale integrated ice water quantity (known as ice water path) retrieval via remote sensing in the microwave band (80-300GHz), where...
Show moreTropospheric cloud ice has a significant impact on the earth's radiative balance and climate, and to help improve the ability to forecast short-term through climatological-scale weather, the importance of quantification of these ice particles is not to be underestimated. To that end, the study presented here describes an attempt to accomplish large spatial-scale integrated ice water quantity (known as ice water path) retrieval via remote sensing in the microwave band (80-300GHz), where effects from ice crystals become detectable via scattering of terrestrial radiation. At the heart of this study is the use of a radiative transfer model in conjunction with data from surface-based instrumentation to simulate atmospheric brightness temperatures at microwave frequencies, and to compare the simulated results to observational data from the Advanced Microwave Sounding Unit - B instrument on the NOAA-15 polar orbiting platform. However, this cannot be done without first discussing the nature of ice crystals in the atmosphere and the scattering modes that result from their interaction with energy, and the implementation of approximations thereof for model usage. Case studies are performed using the model to establish the sensitivity and behavior of the model under differing conditions, and these are compared to real-world data. Subsequently ice water path retrieval from satellite data utilizing Bayesian theory is attempted, with somewhat limited success, and the results hereof are discussed. Finally, known error sources are examined with possibilities for improvement, and ideas for future work in the field presented.
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Date Issued: 2006
Identifier: FSU_migr_etd-0476
Format: Thesis

Title: Microalgae to Biofuel: An Investigation into the Role of the Native Microbial Community in the Cultivation of Algae on Wastewater.
Creator: Smith, Claire, Chanton, Jeffrey, Huettel, Markus, Landing, William, Kostka, Joel, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: The growth of a locally isolated strain of green algae, Chlorella sp., selected for its promise as a biodiesel feedstock, was studied in wastewater effluent from the municipal wastewater treatment plant in Tallahassee FL. Nutrient concentration and microbial community composition within the effluent were profiled at monthly intervals. Adequate nutrients for algal cultivation were observed along with a dynamic microbial community of zooplankton, green algae, diatoms, and a bacterial community...
Show moreThe growth of a locally isolated strain of green algae, Chlorella sp., selected for its promise as a biodiesel feedstock, was studied in wastewater effluent from the municipal wastewater treatment plant in Tallahassee FL. Nutrient concentration and microbial community composition within the effluent were profiled at monthly intervals. Adequate nutrients for algal cultivation were observed along with a dynamic microbial community of zooplankton, green algae, diatoms, and a bacterial community that included Proteobacteria, Bacteroidetes, Cyanobacteria, Firmicutes, and Actinobacteria. The importance of this microbial community in the cultivation of Chlorella and the impact on biofuel production was investigated utilizing mesocosm incubations. Size exclusion was employed to examine the biogeochemical interactions between the Chlorella culture and the resident wastewater microorganisms. The accumulation of algal cells and chl a biomass, the production of oxygen, and the consumption of inorganic carbon and nutrients, along with changes in the microbial community composition were monitored in treatments that included the total wastewater microbial community, the wastewater bacterial community, and the Chlorella culture with no effluent microorganisms. The treatment that excluded the wastewater microbial community and allowed the Chlorella culture to grow uninfluenced, consistently demonstrated the highest abundances of algal cells. A limited abundance of algal cells and chl a biomass were observed in the treatments that contained the total wastewater microbial community, while no limitation in oxygen production or nutrient consumption was observed in these treatments. Given the presence of zooplankton that are known to graze on algal cells, it appears that a top-down control inhibits the accumulation of algal biomass in raw wastewater effluent from a municipal treatment plant. In the treatments that contained the native bacterial community, competition between the Chlorella culture and phototrophic bacteria, i.e. cyanobacteria, was observed. These treatments demonstrated high chl a biomass, but limited accumulation of algal cells, as well as significant consumption of nutrients, indicating that cyanobacteria may out-compete Chlorella for limiting nutrients. However, the heterotrophic bacterial community did appear to have a significant impact on algal growth. Treatments in which the cyanobacterial community was inhibited did not demonstrate a draw-down of limiting nutrients or a limitation in the accumulation of algal cells. In addition, shifts in the composition of the bacterial community, including a reduction in the relative abundance of Betaproteobacteria with a simultaneous increase in the relative abundance of Alphaproteobacteria, Nostocophycideae, and Oscillatoriophycideae were observed, but these shifts occurred independently of the presence of the Chlorella culture, implying that there is not a strong relationship between these two groups. The limitation that occurred in the growth of Chlorella due to competition and top-down controls indicates that without significant manipulations of the microbial community, the cultivation of an algal monoculture in wastewater effluent from a municipal treatment plant may be unrealistic for efficient biofuel feedstock production.
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Date Issued: 2012
Identifier: FSU_migr_etd-5191
Format: Thesis

Title: Microbial Community Diversity Associated with Carbon and Nitrogen Cycling in Permeable Marine Sediments.
Creator: Hunter, Evan M., Kostka, Joel, Mills, Heath, Huettel, Markus, Kerkhof, Lee, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Though a large fraction of primary production and organic matter cycling in the oceans occurs on continental shelves dominated by sandy deposits, the microbial communities associated with permeable shelf sediments remain poorly characterized. Therefore, the primary objective of this study was to provide the first detailed characterization of microbial diversity in representative marine sands of the South Atlantic Bight (SAB) and the northeastern Gulf of Mexico (NEGOM) through analyses of SSU...
Show moreThough a large fraction of primary production and organic matter cycling in the oceans occurs on continental shelves dominated by sandy deposits, the microbial communities associated with permeable shelf sediments remain poorly characterized. Therefore, the primary objective of this study was to provide the first detailed characterization of microbial diversity in representative marine sands of the South Atlantic Bight (SAB) and the northeastern Gulf of Mexico (NEGOM) through analyses of SSU rRNA gene (Bacteria), nosZ (denitrifying bacteria), and amoA (ammonia-oxidizing bacteria) sequences. Communities were analyzed by DNA extraction, clone library construction, and terminal restriction fragment length polymorphism (T-RFLP) community fingerprinting. Sediment characteristics, geochemical parameters, and rate measurements were obtained in parallel with microbial community analysis. Microbiological and biogeochemical approaches were coupled, allowing the structure-function relationships of key microbial groups involved in carbon and nitrogen cycling in continental shelf sediments to be examined. In the SAB study (Ch. 1), clone libraries were constructed from both sediment core material and manipulated sediment within column experiments. Rapid organic matter degradation and coupled nitrification-denitrification were observed in column experiments at flow rates and oxygen concentrations resembling in situ conditions. Numerous SSU rRNA gene phylotypes were affiliated with the phyla Proteobacteria (classes Alpha-, Delta-, and Gammaproteobacteria), Planctomycetes, Cyanobacteria, Chloroflexi and Bacteroidetes. Detectable sequence diversity of nosZ and SSU rRNA genes increased in stratified redox-stabilized columns compared to in situ sediments, with the Alphaproteobacteria comprising the most frequently detected group. Alternatively, nitrifier communities showed a relatively low and stable diversity that did not co-vary with the other gene targets. In the NEGOM study (Ch. 2), high throughput techniques were developed and applied to extensively profile overall and denitrifying microbial communities in a large number of sediment samples over various sediment depth intervals, contrasting sites, and sampling periods. Cloning/sequencing and community fingerprinting (T-RFLP) approaches were applied in parallel to characterize microbial diversity and phylogenetic composition. Statistical estimators including species richness, Shannon-Weiner and 1/D indices, nucleotide diversity, gene diversity, evenness, and theta (pi) indicated little difference between four clone libraries constructed from selected depth intervals (0-2 cm, 18-20 cm) at each site in March. In contrast, T-RFLP profiles and robust phylogenetic analysis showed distinct trends in diversity according to site, depth, and time period sampled. The results elucidate predominant phylotypes that are likely to catalyze carbon and nitrogen cycling in marine sands. Several microbial groups (Deltaproteobacteria, Gammaproteobacteria, Planctomycetes) were confirmed as significant contributors to the microbial communities of permeable marine sediments in agreement with previous work. However, the robust sequence database of this study expanded current knowledge to reveal a large overall community diversity including additional groups (Alphaproteobacteria, Bacteriodetes/Chlorobi, and Cyanobacteria) that had not been previously recognized using cultivation-independent methods with inherently lower resolution. The Alphaproteobacteria, in particular, were shown to be relatively abundant in the overall and denitrifying communities at both SAB and NEGOM sites. Although overall diversity increased in response to redox stabilization and stratification in column experiments, the major phylotypes remained the same, indicating that the columns sufficiently mimic in situ conditions. While SSU rRNA gene phylotypes detected by clonal analysis were similar at the phylum level at all sites, the NEGOM site showed much higher species richness in comparison to SAB. At NEGOM, T-RFLP showed distinct differences in community diversity according to site, depth, and time. The sequence database from this thesis will facilitate the development of improved probes and primer sets to be used in quantifying the metabolically active members of permeable sand communities. Rapid community fingerprinting methods developed here should allow for more extensive comparisons across environmental gradients in order to better understand the factors controlling microbial diversity in permeable sediments.
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Date Issued: 2006
Identifier: FSU_migr_etd-3399
Format: Thesis

Title: Assessing Uncertainty in Simulated Atmospheric Transport and Dispersion Using a WRF-3DVAR Cycling Multiphysics Ensemble.
Creator: Riggi, Antonio Giuseppe, Fuelberg, Henry, Hart, Robert, Ahlquist, Jon, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: This study examines the degree of uncertainty that occurs in atmospheric transport and dispersion (ATD) modeling due to using different parameterizations of physical processes such as shortwave and longwave radiative processes, precipitation formation, and atmosphere-surface interactions. An ensemble approach is taken to examine how this one aspect of meteorological model uncertainty affects subsequent ATD simulations. Differences in these Weather Research and Forecasting (WRF) physics...
Show moreThis study examines the degree of uncertainty that occurs in atmospheric transport and dispersion (ATD) modeling due to using different parameterizations of physical processes such as shortwave and longwave radiative processes, precipitation formation, and atmosphere-surface interactions. An ensemble approach is taken to examine how this one aspect of meteorological model uncertainty affects subsequent ATD simulations. Differences in these Weather Research and Forecasting (WRF) physics configuration strategies are investigated through their effects on offline HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) ATD simulations of three October 2010 tracer releases conducted in a region of complex terrain. The WRF model consists of three nested domains, with the innermost (highest resolution) domain having a horizontal grid spacing of 2 km. A twenty member ensemble of input meteorological data for the ATD simulations is generated through 6 h WRF cycling runs that employ three-dimensional variational data assimilation (3DVAR) on the outer two domains, but not on the innermost domain. Each of the twenty members uses a different combination of WRF physics parameterizations. Characteristics of several aspects of the 3DVAR system are presented. Single observation tests reveal increments that reflect physical balances imposed during the data assimilation process. Consistent RMS error reduction by 3DVAR improves the quality of information provided at the lateral boundaries of the innermost domain (∆x = 2 km). RMS errors of 10-meteruandvwinds are generally reduced by 0.4-0.5 m s−1, and RMS errors of 2-meter temperature are reduced by 1.5-3 K throughout the cycling runs. Considerable spread in PBL height, a key ATD variable, is produced in the innermost domain, especially during the daytime hours (σ = 141-200 m). HYSPLIT dispersion simulations using the ensemble members show a wide spread of ground-level concentration fields, as well as varying degrees of vertical transport, that are a consequence of the choice of model physics configurations, with plume areas sometimes varying by over 1000 km2. Verification metrics quantitatively illustrate the concentrations at the ground truth field study measurement stations that can be obtained by varying the model physics parameterizations. Ensemble-based probabilities provide a useful method of describing the likelihood that a given concentration will be exceeded.
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Date Issued: 2013
Identifier: FSU_migr_etd-8628
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.
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Date Issued: 2004
Identifier: FSU_migr_etd-0395
Format: Thesis

Title: Are Subterranean Estuaries a Source of Chromophoric Dissolved Organic Matter (CDOM) to the Coastal Ocean?: A Case Study in the Northern Gulf of Mexico.
Creator: Suryaputra, I Gusti Ngurah Agung, Huettel, Markus, Dittmar, Thorsten, Burnett, William, Chanton, Jeffrey, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Submarine groundwater discharge (SGD) is a major pathway for nutrient transport in coastal marine systems. There are indications that SGD may also release large amounts of dissolved organic matter (DOM) to the coastal ocean and thus impact coastal ecosystem functioning. DOM is usually quantified as dissolved organic carbon (DOC), which requires discrete sampling. Therefore, detailed time series on tidally-driven SGD cannot easily be obtained for DOC. The chromophoric component of DOM (CDOM)...
Show moreSubmarine groundwater discharge (SGD) is a major pathway for nutrient transport in coastal marine systems. There are indications that SGD may also release large amounts of dissolved organic matter (DOM) to the coastal ocean and thus impact coastal ecosystem functioning. DOM is usually quantified as dissolved organic carbon (DOC), which requires discrete sampling. Therefore, detailed time series on tidally-driven SGD cannot easily be obtained for DOC. The chromophoric component of DOM (CDOM) can be monitored via specific fluorescence in high temporal resolution and in situ. Here we hypothesize that SGD is a significant source of CDOM to the coastal ocean, impacting optical properties and biogeochemical cycles of coastal waters. In this context we also evaluated the possibility of using CDOM as a proxy for DOC in a subterranean estuary. To test our hypothesis, a case study was performed in a shallow bay in the Northern Gulf of Mexico. CDOM was continuously monitored in situ for approximately three weeks in a groundwater well on a beach and 300 m offshore in the adjacent bay. The radon isotope 222Rn was also continuously measured as a conservative tracer for submarine groundwater in the bay. Discrete samples for DOC analysis and associated variables were collected to cover one tidal cycle (15 hours). In a simple SGD model, CDOM concentrations in the bay were predicted by multiplying 222Rn concentrations in the bay (as a measure for SGD) with CDOM concentrations in the well (as the groundwater endmember). This was done for each hour during the entire sampling period. If a lag-time of one hour between groundwater and bay was considered, the predicted CDOM significantly correlated (p<0.01) with the measured CDOM in the bay. Independent statistical tests, including chlorophyll a, salinity and water level data, confirm this finding and demonstrate that CDOM in the bay is mainly driven by freshwater SGD. More detailed analysis of the time series data show that short-term time series of 24 hours or less can lead to erroneous results in estimating SGD. CDOM and DOC significantly correlated for the groundwater endmember, and CDOM could thus be transformed into DOC concentrations. It was estimated that at least 0.6 Mega-mole DOC are delivered to the entire Gulf Coast of Florida in a day via SGD which is similar in order of magnitude as riverine fluxes.
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Date Issued: 2009
Identifier: FSU_migr_etd-1496
Format: Thesis

Title: Developing a Statistical Forecast Model for Initiating Lightning over West Texas and New Mexico.
Creator: Wagner, Geoffrey, Fuelberg, Henry E., Ahlquist, Jon, Ruscher, Paul, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Past binary logistic regression (BLR) and perfect prognosis schemes have shown skill for predicting the probability of one or more cloud-to-ground (CG) lightning flashes for regions such as Florida. This study examines the ability of the BLR and perfect prog techniques to forecast only those flashes at the daily onset of warm season convective activity. A statistical model is developed for two domains in the western United States in the vicinities of Amarillo, Texas and Albuquerque, New...
Show morePast binary logistic regression (BLR) and perfect prognosis schemes have shown skill for predicting the probability of one or more cloud-to-ground (CG) lightning flashes for regions such as Florida. This study examines the ability of the BLR and perfect prog techniques to forecast only those flashes at the daily onset of warm season convective activity. A statistical model is developed for two domains in the western United States in the vicinities of Amarillo, Texas and Albuquerque, New Mexico, to predict the probability of one or more CG flashes during the 1800 UTC to 2100 UTC time window. Warm season convection in these locales is influenced by factors such as the Southwest Monsoon, drylines, and topography. Each domain consisted of a 28 × 26 grid at a 10-km resolution. One equation for each domain was developed using 10-year climatology and predictors from the North American Regional Reanalysis (NARR) dataset for the dependent period May through September of 1994 â 2004. In our perfect prog scheme, the reanalysis data were treated as observations. Forecasts were made for the 2005 warm season, and evaluated using the Brier Score, Brier Skill Score, and reliability diagrams. Due to the relative rarity of the event being forecast, forecast probabilities tended to be small, rarely exceeding the 30% range in the Amarillo domain and 70% (with a majority below 50%) in the Albuquerque domain. Both domains typically exhibited skill over climatology and good reliability for low forecast probabilities, which constituted a majority of the forecasts. Sample forecasts for both domains are examined. The Amarillo model demonstrated competent performance on 10 June 2005, but poor performance on 1 September 2005. The Albuquerque model performed well on 1 September 2005, but performed poorly on 17 July 2005. Despite the low magnitude of probabilities forecast, both models showed promise, commonly placing their relative maxima in the vicinity of the verifying initiating flashes, with some obvious exceptions.
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Date Issued: 2011
Identifier: FSU_migr_etd-1376
Format: Thesis

Title: Determination of Soil Critical Water Content with Bulk Soil Electrical Conductivity.
Creator: Han, Xue, Dudley, Lynn, Salters, Vincent, Ye, Ming, Chen, Gang, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Traditionally, research on bulk electrical conductivity is focused on the subject of soil salinity effects. Herein, bulk electrical conductivity was used to investigate the transport processes of soil. Electrical conductivity indicates the ability of the material to carry the electrons. In soils, water content is the dominant factor controlling conductivity. In addition to water content, salinity, clay content and temperature are also important factors in determining bulk electrical...
Show moreTraditionally, research on bulk electrical conductivity is focused on the subject of soil salinity effects. Herein, bulk electrical conductivity was used to investigate the transport processes of soil. Electrical conductivity indicates the ability of the material to carry the electrons. In soils, water content is the dominant factor controlling conductivity. In addition to water content, salinity, clay content and temperature are also important factors in determining bulk electrical conductivity. Bulk electrical conductivity ECa is composed of the electrical conductivity of the liquid phase and surface electrical conductivity. The concept of critical water content has been proposed by different scientists in different ways. Here the critical water content is defined as the water content when the system transits from disconnected water films to a network of connected water filled pores, the critical water content occurs, mass transport becomes significant and tortuosity decreases. This work investigates the potential of using bulk electrical conductivity ECa to determine the critical water content. We used a relatively uniform sand and clay-sand mixtures as the porous medium instead of a complex soil. A test cell was designed to collect the electrical conductivity data of soil at different water content and the Wenner-array method was used. The electrolyte concentrations used in the experiment were 0.01 M KCl, 0.05 M KCl and 0.10 M KCl. Both error calculation and duplicated experiment has been done to determine the precision of our measurements. A plot of ECa vs. volumetric water content (è) failed to prove the evidence of the critical water content. The data analysis then used a Formation factor, or F factor which is closely related to ECa as a basis. The Fc factor proposed by Low and the F factor proposed by Rhoades were compared and it was determined that Rhoads model was consistent with observed trends. The F factor showed a significant change as water content increased, and samples with more clay had the sudden decrement in F at the higher water contents. Tuller's pore-scale model failed to provide a conceptual model of the observed trends. The critical path analysis (CPA) model provided an explanation of the F factor change with è, The CPA model represents porous medium as a system of large pores and thin pores with larger pores connected by thin pores. At certain water content, there is a critical condition wherein a network of thin pores is filled, and at this critical condition, the larger pores are connected and then mass transport becomes significant and the F factor decreases. The CPA model not only described a progression that fits our F factor data well, suggesting that samples with more clay have more thin pores, so it reaches the critical condition at higher water content.
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Date Issued: 2011
Identifier: FSU_migr_etd-4295
Format: Thesis

Title: Detection of Radio Frequency Interference over Ocean.
Creator: Tian, Xiaoxu, Zou, Xiaolei, Wu, Zhaohua, Ray, Peter S., Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: The geostationary satellite television (TV) signals that are reflected off the ocean surfaces could enter the AMSR-E antenna, resulting in RFI (Radio Frequency Interference) contamination in AMSR-E 10.65 and 18.7 GHz channels. If not detected, the presence of RFI signals can result in false retrievals of oceanic environmental parameters (e.g., sea surface temperature, sea surface wind speed, rain water path) from microwave imaging radiance measurements. This study first examined the geometric...
Show moreThe geostationary satellite television (TV) signals that are reflected off the ocean surfaces could enter the AMSR-E antenna, resulting in RFI (Radio Frequency Interference) contamination in AMSR-E 10.65 and 18.7 GHz channels. If not detected, the presence of RFI signals can result in false retrievals of oceanic environmental parameters (e.g., sea surface temperature, sea surface wind speed, rain water path) from microwave imaging radiance measurements. This study first examined the geometric relationship between the RFI source, geostationary TV satellite, and AMSR-E observation. Then a normalized Principal Component Analysis (NPCA) method is proposed and applied for RFI detection over oceans in Advanced Microwave Scanning Radiometer (AMSR)-E observations. It is found that the RFI-contaminated observations on AMSR-E descending node at 10.65 and 18.7 GHz can be successively detected near coastal areas surrounding Europe and United States continents. The results yielded from the geometric examination at another angle verify those signals detected with NPCA. The proposed NPCA algorithm is applicable in an operational environment for fast data processing and data dissemination, and is different from earlier methods, which often require a priori information.
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Date Issued: 2014
Identifier: FSU_migr_etd-8901
Format: Thesis

Title: Developing Statistical Guidance for Forecasting the Amount of Warm Season Afternoon and Evening Lightning in South Florida.
Creator: Shafer, Phillip Edmond, Fuelberg, Henry E., Ahlquist, Jon, Ruscher, Paul, Watson, Andrew I., Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Fourteen years of cloud-to-ground lightning data from the National Lightning Detection Network, and radiosonde releases from Miami and West Palm Beach, are used to develop statistical guidance equations that forecast the amount of warm season afternoon and evening lightning that is expected over two areas of South Florida that are serviced by Florida Power and Light Corporation (FP&L)-- the eastern halves of Miami-Dade and Broward Counties. A total of 54 parameters are calculated from the...
Show moreFourteen years of cloud-to-ground lightning data from the National Lightning Detection Network, and radiosonde releases from Miami and West Palm Beach, are used to develop statistical guidance equations that forecast the amount of warm season afternoon and evening lightning that is expected over two areas of South Florida that are serviced by Florida Power and Light Corporation (FP&L)-- the eastern halves of Miami-Dade and Broward Counties. A total of 54 parameters are calculated from the soundings to serve as candidate predictors for the equations. These include parameters that describe wind direction and speed in various layers, moisture, temperature, and stability. Day number, persistence, and same day morning lightning also are included as potential predictors of afternoon lightning. A variety of statistical modeling techniques is attempted initially, but many are found to be inappropriate. The best results are obtained by creating four quartile groups of flash count based on climatology, and then using binary logistic regression to develop three prediction equations for each domain, one giving the conditional probability of a quartile one (Q1) lightning event, another for the probability of a quartile three (Q3) or greater event, and a third equation giving the probability of a quartile four (Q4) lightning event. Principal component analysis is used to select a subset of non-redundant predictors that have the greatest physical relevance to convection and lightning in South Florida. The final candidate sounding predictors are the vector mean 1000-700 hPa cross-shore wind component and speed, the K-index, modified Lifted Index, and the temperature at 900 hPa. Non-linear effects are considered by including second, third, and fourth order terms as additional candidate predictors. A combination of stepwise screening and cross-validation is used to select the variables that best generalize to independent data. To determine the most likely quartile of lightning activity, a decision tree scheme is constructed using probability thresholds for the three equations. Finally, the resulting prediction schemes are tested independently using k-fold cross-validation. The dominant effect in each of the equations is the component of the wind perpendicular to the coastline which is found to have a significant non-linear relationship with lightning activity. Other important variables are the K-index and modified Lifted Index. Day number, persistence, and same day morning activity also are selected as important indicators of afternoon lightning in the two domains. When each year is treated independently, the Miami-Dade scheme correctly forecasts the quartile ~ 37% of the time and is correct to within one quartile of the observed ~ 79% of the time. The scheme for eastern Broward County forecasts the correct quartile ~ 36% of the time and is correct to within one quartile ~ 77% of the time. The prediction schemes generally are superior to persistence and climatology for both the dependent data and during k-fold cross-validation. Thus, they possess real forecast skill. For example, when forecasting the correct quartile, these results are a ~ 4-6 percentage point improvement over persistence, and ~ 11-12 percentage point improvement over climatology. In terms of correctly predicting to within one quartile of the observed, the two schemes are an improvement over persistence by ~ 6-8 percentage points and over climatology by ~ 14-17 percentage points. Further analysis shows that the two schemes rarely forecast the upper two quartiles when no activity is observed. Additionally, correct predictions of Q4 events are shown to increase with flash count within the Q4 category. Overall, the cross-validation results show only a 1-2% reduction in skill from what is obtained for the fourteen years of dependent data, demonstrating that the two schemes are statistically robust, and can be expected to achieve similar results when implemented operationally.
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Date Issued: 2004
Identifier: FSU_migr_etd-1803
Format: Thesis

Title: Determining the Error Characteristics of H*WIND.
Creator: Dinapoli, Steven, Bourassa, Mark, Powell, Mark, Hart, Robert, Liu, Guosheng, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: The HRD Real-time Hurricane Wind Analysis System (H*Wind) is a software application used by NOAA's Hurricane Research Division to create a gridded tropical cyclone wind analysis based on a wide range of observations. One application of H*Wind fields is calibration of scatterometers for high wind speed environments. Unfortunately, the accuracy of the H*Wind product has not been studied extensively, and therefore the accuracy of scatterometer calibrations in these environments is also unknown....
Show moreThe HRD Real-time Hurricane Wind Analysis System (H*Wind) is a software application used by NOAA's Hurricane Research Division to create a gridded tropical cyclone wind analysis based on a wide range of observations. One application of H*Wind fields is calibration of scatterometers for high wind speed environments. Unfortunately, the accuracy of the H*Wind product has not been studied extensively, and therefore the accuracy of scatterometer calibrations in these environments is also unknown. This investigation seeks to determine the uncertainty in the H*Wind product and estimate the contributions of several potential error sources. These error sources include random observation errors, relative bias between different data types, temporal drift resulting from combining non-simultaneous measurements, and smoothing and interpolation errors in the H*Wind software. The effects of relative bias between different data types and random observation errors are determined by performing statistical calculations on the observed wind speeds. We show that in the absence of large biases, the total contribution of all error sources results in an uncertainty of approximately 7% near the storm center, which increases to nearly 15% near the tropical storm force wind radius. The H*Wind analysis algorithm is found to introduce a positive bias to the wind speeds near the storm center, where the analyzed wind speeds are enhanced to match the highest observations. In addition, spectral analyses are performed to ensure that the filter wavelength of the final analysis product matches user specifications. With increased knowledge of these error sources and their effects, researchers will have a better understanding of the uncertainty in the H*Wind product, and can then judge the suitability of H*Wind for various research applications
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Date Issued: 2010
Identifier: FSU_migr_etd-0090
Format: Thesis

Title: Determining Surface Winds from Doppler Radar Data during Hurricane Passages over Florida.
Creator: Hayes, Philip D., Fuelberg, Henry E., Stallins, Anthony, Hart, Robert E., Liu, Guosheng, Bourassa, Mark, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: A hurricane's destructive nature must be evaluated on as small a scale as possible to reveal the various types of mesoscale circulations that are embedded within the storm's overall wind field. This research develops a technique to estimate small scale surface wind speeds in hurricanes crossing Florida, and thereby identify areas of anomalous winds. Level II Doppler radar data are analyzed onto a high resolution (1 degree radial, 0.5 km gate) grid. An algorithm is developed to estimate the...
Show moreA hurricane's destructive nature must be evaluated on as small a scale as possible to reveal the various types of mesoscale circulations that are embedded within the storm's overall wind field. This research develops a technique to estimate small scale surface wind speeds in hurricanes crossing Florida, and thereby identify areas of anomalous winds. Level II Doppler radar data are analyzed onto a high resolution (1 degree radial, 0.5 km gate) grid. An algorithm is developed to estimate the total wind speed from a combination of radial velocity and quality controlled reflectivity. These variables are utilized by identifying the location of the eye and then using radial velocities and an assumed symmetric wind field about the eye to estimate the total wind field over the entire radar scan area. Once the total wind field is computed along a scan, reduction factors are used to transpose the winds at the varying beam altitudes down to the surface using similarity theory. Case studies of Hurricanes Jeanne (2004), Frances (2004), Wilma (2005), Irene (1999), Ivan (2004) and Charlie (2004) are investigated. The success of the algorithm depends greatly on the ability of the Weather Surveillance Radar 88 Doppler (WSR-88D) to sample the velocity data and the ability to properly unfold it. Hurricane Wilma is an example of dry air being entrained into the cyclone, which produces an inadequate concentration of targets to provide a velocity profile, thereby resulting in poor results. Computed wind speeds are compared with National Weather Service (NWS) ASOS observations and independent wind observations supplied by the University of Florida. The estimated winds and those from the two datasets exhibit reasonable agreement; however, additional validation is needed to determine the actual skill of the algorithm. The observed data indicate that gust factors are not optimally estimated by applying a uniform percentage of the total wind speed. Further investigation is needed to determine the proper procedure for estimating wind gusts. Results also show that the algorithm can be used with some confidence to diagnose the damage potential for embedded tornadic cells located within the land-falling hurricane.
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Date Issued: 2011
Identifier: FSU_migr_etd-4186
Format: Thesis

Title: Determining the Characteristics of Anvil and Thunderstorm Lightning for Use in the Lightning Launch Commit Criteria at Cape Canaveral Air Force Station and Kennedy Space Center.
Creator: Tamurian, Zachary N., Fuelberg, Henry E., Sura, Philip G., Nicholson, Sharon E., Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: The 45th Weather Squadron (45WS) provides weather support to America's space program at Florida's Cape Canaveral Air Force Station (CCAFS), Kennedy Space Center (KSC), and Patrick Air Force Base (PAFB). Since CCAFS/KSC lies within Florida's "Lightning Alley", summer thunderstorms and associated hazards are a special concern for space launches and all other outdoor activities at CCAFS/KSC. Therefore, the 45WS has developed the Lightning Launch Commit Criteria (LLCC) to help minimize hazards...
Show moreThe 45th Weather Squadron (45WS) provides weather support to America's space program at Florida's Cape Canaveral Air Force Station (CCAFS), Kennedy Space Center (KSC), and Patrick Air Force Base (PAFB). Since CCAFS/KSC lies within Florida's "Lightning Alley", summer thunderstorms and associated hazards are a special concern for space launches and all other outdoor activities at CCAFS/KSC. Therefore, the 45WS has developed the Lightning Launch Commit Criteria (LLCC) to help minimize hazards from lightning (both naturally occurring and triggered) and vehicle electrification during the ascent phase of launch. This study has documented the spatial distributions and time evolution of total lightning and radar reflectivity in and around thunderstorms, attached anvil clouds, and detached anvil clouds near CCAFS/KSC on 30 active lightning days between 2008-11. Our goal was to determine if some of the current LLCC thresholds are too restrictive and represent missed launch opportunities, or not restrictive enough and represent a safety risk. CG flashes originating inside the convective core or its anvil can strike the ground away from the cloud edge. Since these side flashes often strike the ground under clear skies, they commonly are referred to as "bolts from the blue". Our results indicate that the vast majority of CG flashes (~94%) strike the ground = 5 n mi from cloud edge (0 dBZ) whereas 73% of CG flashes are = 3 n mi outside 0 dBZ. Three positive bolts from the blue were documented, and all came from the same storm on 29 May 2009. One of the positive flashes propagated 8.91 n mi from cloud edge. Anvil initiated lightning can distribute charge after detachment, but only for a short period. We analyzed 100 anvils within 100 km of KSC; 895 IC flashes in the anvil were initiated in the core of the storms. The first core initiated flash of each anvil typically propagated = 10 n mi. Cellular thunderstorms produce the greatest percentage of total lightning (~84%) in our dataset, but average flash distances from the core are greatest in attached anvils (~4.98 n mi). To our knowledge this is the first study to quantify the distances that lightning can extend beyond the edge of clouds. We believe the results of this research should be considered before making additional changes to the LLCC.
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Date Issued: 2012
Identifier: FSU_migr_etd-5223
Format: Thesis

Title: Developing Statistical Guidance for Afternoon Lightning Activity in Portions of Two South Florida Counties.
Creator: Winarchick, Justin Marsh, Fuelberg, Henry E., Kim, Kwang Yul, Cunningham, Philip, Department of Earth, Ocean and Atmospheric Sciences, Florida State University
Abstract/Description: Statistical guidance equations are developed to determine the probability of noon to midnight lightning activity (the occurrence or non occurrence of at least one flash) in eastern Miami-Dade and Broward Counties during the warm season (May-September). The guidance assumes that the sea breeze provides the dominant forcing for afternoon convective and lightning activity. The guidance product is developed to assist Florida Power and Light Corporation personnel in deciding whether extra line...
Show moreStatistical guidance equations are developed to determine the probability of noon to midnight lightning activity (the occurrence or non occurrence of at least one flash) in eastern Miami-Dade and Broward Counties during the warm season (May-September). The guidance assumes that the sea breeze provides the dominant forcing for afternoon convective and lightning activity. The guidance product is developed to assist Florida Power and Light Corporation personnel in deciding whether extra line crews will be needed after normal business hours. Fourteen years (1989-2002) of warm season lightning data from the National Lightning Detection Network and 1200 UTC Miami radiosonde data are used to develop and test the guidance equations. The lightning data document whether lightning occurred within the areas of interest during the noon to midnight time period. The radiosonde data are used to calculate fifty-four potential predictors, including wind, moisture, stability and temperature parameters. Two persistence variables (the previous day's afternoon activity and the current day's morning activity) also are included as potential predictors. Binary logistic regression is used to relate the noon to midnight lightning activity to the pool of potential predictors. A stepwise screening procedure is used to build separate models for each month during the warm season for both counties. Deriving separate monthly models is found to improve forecast skill compared to a single warm season model. Each monthly model generally contains persistence and the wind, moisture, and stability parameters which are known to influence the strength and movement of the sea breeze and convective development. A cross-validation procedure is used to test the models on independent data and to determine the stability of the models. The cross-validation process reveals that the models are statistically stable and perform well when tested on independent data. The probability of detection, calculated from the independent testing, ranges from ~67% during May to ~90% in August, while false alarm rates range from ~30% during May to only 15% in August. Results from independent testing of the models also show that they improve on forecasts based solely on persistence. For example, the threat score for the guidance equations is ~69% versus ~61% for persistence alone. Furthermore, the hit rate improves from ~71% to ~77%. Although persistence is a powerful predictor of lightning activity in South Florida during the warm season, the guidance equations provide superior results. Days when the models produced an incorrect forecast are examined. When no lightning was forecast but occurred anyway, quartiles of lightning activity are considered. The percent of incorrect forecasts decreases from low activity days (i.e., 1st quartile days, 1-7 afternoon flashes) to high activity days (4th quartile days, >125 afternoon flashes). Thus, incorrect forecasts are least likely on the most important days. Fewer days with lightning occurrence are incorrectly forecast during July and August than during May. A similar trend is observed on days when no noon to midnight lightning was observed but had been forecast.125 afternoon flashes). Thus, incorrect forecasts are least likely on the most important days. Fewer days with lightning occurrence are incorrectly forecast during July and August than during May. A similar trend is observed on days when no noon to midnight lightning was observed but had been forecast.
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Date Issued: 2004
Identifier: FSU_migr_etd-0939
Format: Thesis

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