Search results

Title: Spatiotemporal Variability Of No2 And Pm2.5 Over Eastern China: Observational And Model Analyses With A Novel Statistical Method.
Creator: Liu, Mengyao, Lin, Jintai, Wang, Yuchen, Sun, Yang, Zheng, Bo, Shao, Jingyuan, Chen, Lulu, Zheng, Yixuan, Chen, Jinxuan, Fu, Tzung-May, Yan, Yingying, Zhang, Qiang, Wu, Zhaohua
Abstract/Description: Eastern China (27-41 degrees N, 110-123 degrees E) is heavily polluted by nitrogen dioxide (NO2), particulate matter with aerodynamic diameter below 2.5 mu m (PM2.5), and other air pollutants. These pollutants vary on a variety of temporal and spatial scales, with many temporal scales that are nonperiodic and nonstationary, challenging proper quantitative characterization and visualization. This study uses a newly compiled EOF-EEMD analysis visualization package to evaluate the spatiotemporal...
Show moreEastern China (27-41 degrees N, 110-123 degrees E) is heavily polluted by nitrogen dioxide (NO2), particulate matter with aerodynamic diameter below 2.5 mu m (PM2.5), and other air pollutants. These pollutants vary on a variety of temporal and spatial scales, with many temporal scales that are nonperiodic and nonstationary, challenging proper quantitative characterization and visualization. This study uses a newly compiled EOF-EEMD analysis visualization package to evaluate the spatiotemporal variability of ground-level NO2, PM2.5, and their associations with meteorological processes over Eastern China in fall-winter 2013. Applying the package to observed hourly pollutant data reveals a primary spatial pattern representing Eastern China synchronous variation in time, which is dominated by diurnal variability with a much weaker day-to-day signal. A secondary spatial mode, representing north-south opposing changes in time with no constant period, is characterized by wind-related dilution or a buildup of pollutants from one day to another. We further evaluate simulations of nested GEOS-Chem v9-02 and WRF/CMAQ v5.0.1 in capturing the spatiotemporal variability of pollutants. GEOS-Chem underestimates NO2 by about 17 mu g m(-3) and PM2.5 by 35 mu g m(-3 )on average over fall-winter 2013. It reproduces the diurnal variability for both pollutants. For the day-to-day variation, GEOS-Chem reproduces the observed north-south contrasting mode for both pollutants but not the Eastern China synchronous mode (especially for NO2). The model errors are due to a first model layer too thick (about 130 m) to capture the near-surface vertical gradient, deficiencies in the nighttime nitrogen chemistry in the first layer, and missing secondary organic aerosols and anthropogenic dust. CMAQ overestimates the diurnal cycle of pollutants due to too-weak boundary layer mixing, especially in the nighttime, and overestimates NO2 by about 30 mu g m(-3) and PM2.5 by 60 mu g m(-3). For the day-to-day variability, CMAQ reproduces the observed Eastern China synchronous mode but not the north-south opposing mode of NO2. Both models capture the day-to-day variability of PM2.5 better than that of NO2. These results shed light on model improvement. The EOF-EEMD package is freely available for noncommercial uses.
Show less
Date Issued: 2018-09-07
Identifier: FSU_libsubv1_wos_000444030500003, 10.5194/acp-18-12933-2018
Format: Citation

Title: Statistical Evidence For The Role Of Southwestern Indian Ocean Heat Content In The Indian Summer Monsoon Rainfall.
Creator: Venugopal, T., Ali, M. M., Bourassa, M. A., Zheng, Y., Goni, G. J., Foltz, G. R., Rajeevan, M.
Abstract/Description: This study examines the benefit of using Ocean Mean Temperature (OMT) to aid in the prediction of the sign of Indian Summer Monsoon Rainfall (ISMR) anomalies. This is a statistical examination, rather than a process study. The thermal energy needed for maintaining and intensifying hurricanes and monsoons comes from the upper ocean, not just from the thin layer represented by sea surface temperature (SST) alone. Here, we show that the southwestern Indian OMT down to the depth of the 26 degrees...
Show moreThis study examines the benefit of using Ocean Mean Temperature (OMT) to aid in the prediction of the sign of Indian Summer Monsoon Rainfall (ISMR) anomalies. This is a statistical examination, rather than a process study. The thermal energy needed for maintaining and intensifying hurricanes and monsoons comes from the upper ocean, not just from the thin layer represented by sea surface temperature (SST) alone. Here, we show that the southwestern Indian OMT down to the depth of the 26 degrees C isotherm during January-March is a better qualitative predictor of the ISMR than SST. The success rate in predicting above-or below-average ISMR is 80% for OMT compared to 60% for SST. Other January-March mean climate indices (e.g., NINO3.4, Indian Ocean Dipole Mode Index, El Nino Southern Oscillation Modoki Index) have less predictability (52%, 48%, and 56%, respectively) than OMT percentage deviation (PD) (80%). Thus, OMT PD in the southwestern Indian Ocean provides a better qualitative prediction of ISMR by the end of March and indicates whether the ISMR will be above or below the climatological mean value.
Show less
Date Issued: 2018-08-14
Identifier: FSU_libsubv1_wos_000441536700011, 10.1038/s41598-018-30552-0
Format: Citation

Title: Statistical Evidence for the Role of Southwestern Indian Ocean Heat Content in the Indian Summer Monsoon Rainfall.
Creator: Venugopal, T, Ali, M M, Bourassa, M A, Zheng, Y, Goni, G J, Foltz, G R, Rajeevan, M
Abstract/Description: This study examines the benefit of using Ocean Mean Temperature (OMT) to aid in the prediction of the sign of Indian Summer Monsoon Rainfall (ISMR) anomalies. This is a statistical examination, rather than a process study. The thermal energy needed for maintaining and intensifying hurricanes and monsoons comes from the upper ocean, not just from the thin layer represented by sea surface temperature (SST) alone. Here, we show that the southwestern Indian OMT down to the depth of the 26 °C...
Show moreThis study examines the benefit of using Ocean Mean Temperature (OMT) to aid in the prediction of the sign of Indian Summer Monsoon Rainfall (ISMR) anomalies. This is a statistical examination, rather than a process study. The thermal energy needed for maintaining and intensifying hurricanes and monsoons comes from the upper ocean, not just from the thin layer represented by sea surface temperature (SST) alone. Here, we show that the southwestern Indian OMT down to the depth of the 26 °C isotherm during January-March is a better qualitative predictor of the ISMR than SST. The success rate in predicting above- or below-average ISMR is 80% for OMT compared to 60% for SST. Other January-March mean climate indices (e.g., NINO3.4, Indian Ocean Dipole Mode Index, El Niño Southern Oscillation Modoki Index) have less predictability (52%, 48%, and 56%, respectively) than OMT percentage deviation (PD) (80%). Thus, OMT PD in the southwestern Indian Ocean provides a better qualitative prediction of ISMR by the end of March and indicates whether the ISMR will be above or below the climatological mean value.
Show less
Date Issued: 2018-08-14
Identifier: FSU_pmch_30108244, 10.1038/s41598-018-30552-0, PMC6092415, 30108244, 30108244, 10.1038/s41598-018-30552-0
Format: Citation

Title: A New Approach For Incorporating N-15 Isotopic Data Into Linear Inverse Ecosystem Models With Markov Chain Monte Carlo Sampling.
Creator: Stukel, Michael R., Decima, Moira, Kelly, Thomas B.
Abstract/Description: Oceanographic field programs often use delta N-15 biogeochemical measurements and in situ rate measurements to investigate nitrogen cycling and planktonic ecosystem structure. However, integrative modeling approaches capable of synthesizing these distinct measurement types are lacking. We develop a novel approach for incorporating delta N-15 isotopic data into existing Markov Chain Monte Carlo (MCMC) random walk methods for solving linear inverse ecosystem models. We test the ability of this...
Show moreOceanographic field programs often use delta N-15 biogeochemical measurements and in situ rate measurements to investigate nitrogen cycling and planktonic ecosystem structure. However, integrative modeling approaches capable of synthesizing these distinct measurement types are lacking. We develop a novel approach for incorporating delta N-15 isotopic data into existing Markov Chain Monte Carlo (MCMC) random walk methods for solving linear inverse ecosystem models. We test the ability of this approach to recover food web indices (nitrate uptake, nitrogen fixation, zooplankton trophic level, and secondary production) derived from forward models simulating the planktonic ecosystems of the California Current and Amazon River Plume. We show that the MCMC with delta N-15 approach typically does a better job of recovering ecosystem structure than the standard MCMC or L-2 minimum norm (L2MN) approaches, and also outperforms an L2MN with delta N-15 approach. Furthermore, we find that the MCMC with delta N-15 approach is robust to the removal of input equations and hence is well suited to typical pelagic ecosystem studies for which the system is usually vastly under-constrained. Our approach is easily extendable for use with delta C-13 isotopic measurements or variable carbon:nitrogen stoichiometry.
Show less
Date Issued: 2018-06-18
Identifier: FSU_libsubv1_wos_000435528600077, 10.1371/journal.pone.0199123
Format: Citation

Title: A new approach for incorporating 15N isotopic data into linear inverse ecosystem models with Markov Chain Monte Carlo sampling.
Creator: Stukel, Michael R, Décima, Moira, Kelly, Thomas B
Abstract/Description: Oceanographic field programs often use δ15N biogeochemical measurements and in situ rate measurements to investigate nitrogen cycling and planktonic ecosystem structure. However, integrative modeling approaches capable of synthesizing these distinct measurement types are lacking. We develop a novel approach for incorporating δ15N isotopic data into existing Markov Chain Monte Carlo (MCMC) random walk methods for solving linear inverse ecosystem models. We test the ability of this approach to...
Show moreOceanographic field programs often use δ15N biogeochemical measurements and in situ rate measurements to investigate nitrogen cycling and planktonic ecosystem structure. However, integrative modeling approaches capable of synthesizing these distinct measurement types are lacking. We develop a novel approach for incorporating δ15N isotopic data into existing Markov Chain Monte Carlo (MCMC) random walk methods for solving linear inverse ecosystem models. We test the ability of this approach to recover food web indices (nitrate uptake, nitrogen fixation, zooplankton trophic level, and secondary production) derived from forward models simulating the planktonic ecosystems of the California Current and Amazon River Plume. We show that the MCMC with δ15N approach typically does a better job of recovering ecosystem structure than the standard MCMC or L2 minimum norm (L2MN) approaches, and also outperforms an L2MN with δ15N approach. Furthermore, we find that the MCMC with δ15N approach is robust to the removal of input equations and hence is well suited to typical pelagic ecosystem studies for which the system is usually vastly under-constrained. Our approach is easily extendable for use with δ13C isotopic measurements or variable carbon:nitrogen stoichiometry.
Show less
Date Issued: 2018-06-18
Identifier: FSU_pmch_29912928, 10.1371/journal.pone.0199123, PMC6005467, 29912928, 29912928, PONE-D-18-03219
Format: Citation

Title: Geographical Distribution Of Diurnal And Semidiurnal Parametric Subharmonic Instability In A Global Ocean Circulation Model.
Creator: Ansong, Joseph K., Arbic, Brian K., Simmons, Harper L., Alford, Matthew H., Buijsman, Maarten C., Timko, Patrick G., Richman, James G., Shriver, Jay F., Wallcraft, Alan J.
Abstract/Description: The evidence for, baroclinic energetics of, and geographic distribution of parametric subharmonic instability (PSI) arising from both diurnal and semidiurnal tides in a global ocean general circulation model is investigated using 1/12.5 degrees and 1/25 degrees simulations that are forced by both atmospheric analysis fields and the astronomical tidal potential. The paper examines whether PSI occurs in the model, and whether it accounts for a significant fraction of the tidal baroclinic energy...
Show moreThe evidence for, baroclinic energetics of, and geographic distribution of parametric subharmonic instability (PSI) arising from both diurnal and semidiurnal tides in a global ocean general circulation model is investigated using 1/12.5 degrees and 1/25 degrees simulations that are forced by both atmospheric analysis fields and the astronomical tidal potential. The paper examines whether PSI occurs in the model, and whether it accounts for a significant fraction of the tidal baroclinic energy loss. Using energy transfer calculations and bispectral analyses, evidence is found for PSI around the critical latitudes of the tides. The intensity of both diurnal and semidiurnal PSI in the simulations is greatest in the upper ocean, consistent with previous results from idealized simulations, and quickly drops off about 5 degrees from the critical latitudes. The sign of energy transfer depends on location; the transfer is positive (from the tides to subharmonic waves) in some locations and negative in others. The net globally integrated energy transfer is positive in all simulations and is 0.5%-10% of the amount of energy required to close the baroclinic energy budget in the model. The net amount of energy transfer is about an order of magnitude larger in the 1/25 degrees semidiurnal simulation than the 1/12.5 degrees one, implying the dependence of the rate of energy transfer on model resolution.
Show less
Date Issued: 2018-06-01
Identifier: FSU_libsubv1_wos_000437215800012, 10.1175/JPO-D-17-0164.1
Format: Citation

Title: Downscaling Future Climate Change Projections Over Puerto Rico Using A Non-hydrostatic Atmospheric Model.
Creator: Bhardwaj, Amit, Misra, Vasubandhu, Mishra, Akhilesh, Wootten, Adrienne, Boyles, Ryan, Bowden, J. H., Terando, Adam J.
Abstract/Description: We present results from 20-year "high-resolution" regional climate model simulations of precipitation change for the sub-tropical island of Puerto Rico. The Japanese Meteorological Agency Non-Hydrostatic Model (NHM) operating at a 2-km grid resolution is nested inside the Regional Spectral Model (RSM) at 10-km grid resolution, which in turn is forced at the lateral boundaries by the Community Climate System Model (CCSM4). At this resolution, the climate change experiment allows for deep...
Show moreWe present results from 20-year "high-resolution" regional climate model simulations of precipitation change for the sub-tropical island of Puerto Rico. The Japanese Meteorological Agency Non-Hydrostatic Model (NHM) operating at a 2-km grid resolution is nested inside the Regional Spectral Model (RSM) at 10-km grid resolution, which in turn is forced at the lateral boundaries by the Community Climate System Model (CCSM4). At this resolution, the climate change experiment allows for deep convection in model integrations, which is an important consideration for sub-tropical regions in general, and on islands with steep precipitation gradients in particular that strongly influence local ecological processes and the provision of ecosystem services. Projected precipitation change for this region of the Caribbean is simulated for the mid-twenty-first century (2041-2060) under the RCP8.5 climate-forcing scenario relative to the late twentieth century (1986-2005). The results show that by the mid-twenty-first century, there is an overall rainfall reduction over the island for all seasons compared to the recent climate but with diminished mid-summer drought (MSD) in the northwestern parts of the island. Importantly, extreme rainfall events on sub-daily and daily time scales also become slightly less frequent in the projected mid-twenty-first-century climate over most regions of the island.
Show less
Date Issued: 2018-03
Identifier: FSU_libsubv1_wos_000425959700011, 10.1007/s10584-017-2130-x
Format: Citation

Title: The Role of Rough Topography in Mediating Impacts of Bottom Drag in Eddying Ocean Circulation Models.
Creator: Trossman, David S, Arbic, Brian K, Straub, David N, Richman, James G, Chassignet, Eric P, Wallcraft, Alan J, Xu, Xiaobiao
Abstract/Description: Motivated by the substantial sensitivity of eddies in two-layer quasi-geostrophic (QG) turbulence models to the strength of bottom drag, this study explores the sensitivity of eddies in more realistic ocean general circulation model (OGCM) simulations to bottom drag strength. The OGCM results are interpreted using previous results from horizontally homogeneous, two-layer, flat-bottom, f-plane, doubly periodic QG turbulence simulations and new results from two-layer -plane QG turbulence...
Show moreMotivated by the substantial sensitivity of eddies in two-layer quasi-geostrophic (QG) turbulence models to the strength of bottom drag, this study explores the sensitivity of eddies in more realistic ocean general circulation model (OGCM) simulations to bottom drag strength. The OGCM results are interpreted using previous results from horizontally homogeneous, two-layer, flat-bottom, f-plane, doubly periodic QG turbulence simulations and new results from two-layer -plane QG turbulence simulations run in a basin geometry with both flat and rough bottoms. Baroclinicity in all of the simulations varies greatly with drag strength, with weak drag corresponding to more barotropic flow and strong drag corresponding to more baroclinic flow. The sensitivity of the baroclinicity in the QG basin simulations to bottom drag is considerably reduced, however, when rough topography is used in lieu of a flat bottom. Rough topography reduces the sensitivity of the eddy kinetic energy amplitude and horizontal length scales in the QG basin simulations to bottom drag to an even greater degree. The OGCM simulation behavior is qualitatively similar to that in the QG rough bottom basin simulations in that baroclinicity is more sensitive to bottom drag strength than are eddy amplitudes or horizontal length scales. Rough topography therefore appears to mediate the sensitivity of eddies in models to the strength of bottom drag. The sensitivity of eddies to parameterized topographic internal lee wave drag, which has recently been introduced into some OGCMs, is also briefly discussed. Wave drag acts like a strong bottom drag in that it increases the baroclinicity of the flow, without strongly affecting eddy horizontal length scales.
Show less
Date Issued: 2017-08-01
Identifier: FSU_pmch_29657336, 10.1175/JPO-D-16-0229.1, PMC5893158, 29657336, 29657336
Format: Citation

Title: Semidiurnal Internal Tide Incoherence In The Equatorial Pacific.
Creator: Buijsman, Maarten C., Arbic, Brian K., Richman, James G., Shriver, Jay F., Wallcraft, Alan J., Zamudio, Luis
Abstract/Description: The jets in the equatorial Pacific Ocean of a realistically forced global circulation model with a horizontal resolution of 1/12.5 degrees cause a strong loss of phase coherence in semidiurnal internal tides that propagate equatorward from the French Polynesian Islands and Hawaii. This loss of coherence is quantified with a baroclinic energy analysis, in which the semidiurnal-band terms are separated into coherent, incoherent, and cross terms. For time scales longer than a year, the coherent...
Show moreThe jets in the equatorial Pacific Ocean of a realistically forced global circulation model with a horizontal resolution of 1/12.5 degrees cause a strong loss of phase coherence in semidiurnal internal tides that propagate equatorward from the French Polynesian Islands and Hawaii. This loss of coherence is quantified with a baroclinic energy analysis, in which the semidiurnal-band terms are separated into coherent, incoherent, and cross terms. For time scales longer than a year, the coherent energy flux approaches zero values at the equator, while the total flux is similar to 500 W/m. The time variability of the incoherent energy flux is compared with the internal-tide travel-time variability, which is based on along-beam integrated phase speeds computed with the Taylor-Goldstein equation. The variability of monthly mean Taylor-Goldstein phase speeds agrees well with the phase speed variability inferred from steric sea surface height phases extracted with a plane-wave fit technique. On monthly time scales, the loss of phase coherence in the equatorward beams from the French Polynesian Islands is attributed to the time variability in the vertically sheared background flow associated with the jets and tropical instability waves. On an annual time scale, the effect of stratification variability is of equal or greater importance than the shear variability is to the loss of coherence. In the model simulations, low-frequency equatorial jets do not noticeably enhance the dissipation of the internal tide, but merely decohere and scatter it.
Show less
Date Issued: 2017-07
Identifier: FSU_libsubv1_wos_000409893600005, 10.1002/2016JC012590
Format: Citation

Title: Assessing Crop Yield Simulations Driven By The Narccap Regional Climate Models In The Southeast United States.
Creator: Shin, D. W., Baigorria, Guillermo A., Romero, Consuelo C., Cocke, Steve, Oh, Ji-Hyun, Kim, Baek-Min
Abstract/Description: A set of the North American Regional Climate Change Assessment Program (NARCCAP) regional climate models is used in crop modeling systems to assess economically valuable agricultural production in the southeast United States, where weather/climate exerts strong impact on agriculture. The maize/peanut/ cotton yield amounts for the period of 1981-2003 are obtained in a regularly gridded (similar to 20km) southeast U.S. using (a) observed, (b) a reanalysis, and (c) the NARCCAP Phase I multimodel...
Show moreA set of the North American Regional Climate Change Assessment Program (NARCCAP) regional climate models is used in crop modeling systems to assess economically valuable agricultural production in the southeast United States, where weather/climate exerts strong impact on agriculture. The maize/peanut/ cotton yield amounts for the period of 1981-2003 are obtained in a regularly gridded (similar to 20km) southeast U.S. using (a) observed, (b) a reanalysis, and (c) the NARCCAP Phase I multimodel data set. It is shown that the regional-climate model-driven crop yield amounts are better simulated than the reanalysis-driven ones. Multimodel ensemble methods are then adopted to examine their usefulness in improving the simulation of regional crop yield amounts and are compared to each other. The bias-corrected or weighted composite methods combine the crop yield ensemble members better than the simple compositemethod. In general, the weighted ensemble crop yield simulations match marginally better with the observed-weather-driven yields compared to those of the other ensemble methods.
Show less
Date Issued: 2017-03-16
Identifier: FSU_libsubv1_wos_000398064200002, 10.1002/2016JD025576
Format: Citation

Title: Comparison of the ocean surface vector winds from atmospheric reanalysis and scatterometer-based wind products over the Nordic Seas and the northern North Atlantic and their application for ocean modeling.
Creator: Dukhovskoy, Dmitry S., Bourassa, Mark A., Petersen, Guðrún Nína, Steffen, John
Abstract/Description: Ocean surface vector wind fields from reanalysis data sets and scatterometer-derived gridded products are analyzed over the Nordic Seas and the northern North Atlantic for the time period from 2000 to 2009. The data sets include the National Center for Environmental Prediction Reanalysis 2 (NCEPR2), Climate Forecast System Reanalysis (CFSR), Arctic System Reanalysis (ASR), Cross-Calibrated Multiplatform (CCMP) wind product version 1.1 and recently released version 2.0, and QuikSCAT. The goal...
Show moreOcean surface vector wind fields from reanalysis data sets and scatterometer-derived gridded products are analyzed over the Nordic Seas and the northern North Atlantic for the time period from 2000 to 2009. The data sets include the National Center for Environmental Prediction Reanalysis 2 (NCEPR2), Climate Forecast System Reanalysis (CFSR), Arctic System Reanalysis (ASR), Cross-Calibrated Multiplatform (CCMP) wind product version 1.1 and recently released version 2.0, and QuikSCAT. The goal of the study is to assess discrepancies across the wind vector fields in the data sets and demonstrate possible implications of these differences for ocean modeling. Large-scale and mesoscale characteristics of winds are compared at interannual, seasonal, and synoptic timescales. A cyclone tracking methodology is developed and applied to the wind fields to compare cyclone characteristics in the data sets. Additionally, the winds are evaluated against observations collected from meteorological buoys deployed in the Iceland and Irminger Seas. The agreement among the wind fields is better for longer time and larger spatial scales. The discrepancies are clearly apparent for synoptic timescales and mesoscales. CCMP, ASR, and CFSR show the closest overall agreement with each other. Substantial biases are found in the NCEPR2 winds. Numerical sensitivity experiments are conducted with a coupled ice-ocean model forced by different wind fields. The experiments demonstrate differences in the net surface heat fluxes during storms. In the experiment forced by NCEPR2 winds, there are discrepancies in the large-scale wind-driven ocean dynamics compared to the other experiments.
Show less
Date Issued: 2017-03-11
Identifier: FSU_libsubv1_scholarship_submission_1487714204, 10.1002/2016JC012453
Format: Citation

Title: Frequency Content Of Sea Surface Height Variability From Internal Gravity Waves To Mesoscale Eddies.
Creator: Savage, Anna C., Arbic, Brian K., Richman, James G., Shriver, Jay F., Alford, Matthew H., Buijsman, Maarten C., Farrar, J. Thomas, Sharma, Hari, Voet, Gunnar, Wallcraft, Alan J....
Show moreSavage, Anna C., Arbic, Brian K., Richman, James G., Shriver, Jay F., Alford, Matthew H., Buijsman, Maarten C., Farrar, J. Thomas, Sharma, Hari, Voet, Gunnar, Wallcraft, Alan J., Zamudio, Luis
Show less
Abstract/Description: High horizontal-resolution (1/12: 5 degrees and 1/25 degrees) 41-layer global simulations of the HYbrid Coordinate Ocean Model (HYCOM), forced by both atmospheric fields and the astronomical tidal potential, are used to construct global maps of sea surface height (SSH) variability. The HYCOM output is separated into steric and nonsteric and into subtidal, diurnal, semidiurnal, and supertidal frequency bands. The model SSH output is compared to two data sets that offer some geographical...
Show moreHigh horizontal-resolution (1/12: 5 degrees and 1/25 degrees) 41-layer global simulations of the HYbrid Coordinate Ocean Model (HYCOM), forced by both atmospheric fields and the astronomical tidal potential, are used to construct global maps of sea surface height (SSH) variability. The HYCOM output is separated into steric and nonsteric and into subtidal, diurnal, semidiurnal, and supertidal frequency bands. The model SSH output is compared to two data sets that offer some geographical coverage and that also cover a wide range of frequencies-a set of 351 tide gauges that measure full SSH and a set of 14 in situ vertical profilers from which steric SSH can be calculated. Three of the global maps are of interest in planning for the upcoming Surface Water and Ocean Topography (SWOT) two-dimensional swath altimeter mission: (1) maps of the total and (2) nonstationary internal tidal signal (the latter calculated after removing the stationary internal tidal signal via harmonic analysis), with an average variance of 1: 05 and 0: 43 cm(2), respectively, for the semidiurnal band, and (3) a map of the steric supertidal contributions, which are dominated by the internal gravity wave continuum, with an average variance of 0: 15 cm2. Stationary internal tides (which are predictable), nonstationary internal tides (which will be harder to predict), and nontidal internal gravity waves (which will be very difficult to predict) may all be important sources of high-frequency "noise" that could mask lower frequency phenomena in SSH measurements made by the SWOT mission.
Show less
Date Issued: 2017-03
Identifier: FSU_libsubv1_wos_000400678900047, 10.1002/2016JC012331
Format: Citation

Title: Semidiurnal Internal Tide Energy Fluxes And Their Variability In A Global Ocean Model And Moored Observations.
Creator: Ansong, Joseph K., Arbic, Brian K., Alford, Matthew H., Buijsman, Maarten C., Shriver, Jay F., Zhao, Zhongxiang, Richman, James G., Simmons, Harper L., Timko, Patrick G.,...
Show moreAnsong, Joseph K., Arbic, Brian K., Alford, Matthew H., Buijsman, Maarten C., Shriver, Jay F., Zhao, Zhongxiang, Richman, James G., Simmons, Harper L., Timko, Patrick G., Wallcraft, Alan J., Zamudio, Luis
Show less
Abstract/Description: We examine the temporal means and variability of the semidiurnal internal tide energy fluxes in 1/25 degrees global simulations of the Hybrid Coordinate Ocean Model (HYCOM) and in a global archive of 79 historical moorings. Low-frequency flows, a major cause of internal tide variability, have comparable kinetic energies at the mooring sites in model and observations. The computed root-mean-square (RMS) variability of the energy flux is large in both model and observations and correlates...
Show moreWe examine the temporal means and variability of the semidiurnal internal tide energy fluxes in 1/25 degrees global simulations of the Hybrid Coordinate Ocean Model (HYCOM) and in a global archive of 79 historical moorings. Low-frequency flows, a major cause of internal tide variability, have comparable kinetic energies at the mooring sites in model and observations. The computed root-mean-square (RMS) variability of the energy flux is large in both model and observations and correlates positively with the time-averaged flux magnitude. Outside of strong generation regions, the normalized RMS variability (the RMS variability divided by the mean) is nearly independent of the flux magnitudes in the model, and of order 23% or more in both the model and observations. The spatially averaged flux magnitudes in observations and the simulation agree to within a factor of about 1.4 and 2.4 for vertical mode-1 and mode-2, respectively. The difference in energy flux computed from the full-depth model output versus model output subsampled at mooring instrument depths is small. The global historical archive is supplemented with six high-vertical resolution moorings from the Internal Waves Across the Pacific (IWAP) experiment. The model fluxes agree more closely with the high-resolution IWAP fluxes than with the historical mooring fluxes. The high variability in internal tide energy fluxes implies that internal tide fluxes computed from short observational records should be regarded as realizations of a highly variable field, not as "means" that are indicative of conditions at the measurement sites over all time.
Show less
Date Issued: 2017-03
Identifier: FSU_libsubv1_wos_000400678900015, 10.1002/2016JC012184
Format: Citation

Title: Temperature-Salinity Structure of the North Atlantic Circulation and Associated Heat and Freshwater Transports.
Creator: Xu, Xiaobiao, Rhines, Peter B., Chassignet, Eric P.
Abstract/Description: This study investigates the circulation structure and relative contribution of circulation components to the time-mean meridional heat and freshwater transports in the North Atlantic, using numerical results of a high-resolution ocean model that are shown to be in excellent agreement with the observations. The North Atlantic circulation can be separated into the large-scale Atlantic meridional overturning circulation (AMOC) that is diapycnal and the subtropical and subpolar gyres that largely...
Show moreThis study investigates the circulation structure and relative contribution of circulation components to the time-mean meridional heat and freshwater transports in the North Atlantic, using numerical results of a high-resolution ocean model that are shown to be in excellent agreement with the observations. The North Atlantic circulation can be separated into the large-scale Atlantic meridional overturning circulation (AMOC) that is diapycnal and the subtropical and subpolar gyres that largely flow along isopycnal surfaces but also include prominent gyre-scale diapycnal overturning in the Subtropical Mode Water and Labrador Sea Water. Integrals of the meridional volume transport as a function of potential temperature theta and salinity S yield streamfunctions with respect to theta and to S, and heat functions. These argue for a significant contribution to the heat transport by the southward circulation of North Atlantic Deep Water. At 26.5 degrees N, the isopycnic component of the subtropical gyre is colder and fresher in the northward-flowing western boundary currents than the southward return flows, and it carries heat southward and freshwater northward, opposite of that of the diapycnal component. When combined, the subtropical gyre contributes virtually zero to the heat transport and the AMOC is responsible for all the heat transport across this latitude. The subtropical gyre however significantly contributes to the freshwater transport, reducing the 0.5-Sv (1 Sv =10(6) m(3) s(-1)) southward AMOC freshwater transport by 0.13 Sv. In the subpolar North Atlantic near 58 degrees N, the diapycnal component of the circulation, or the transformation of warm saline upper Atlantic water into colder fresher deep waters, is responsible for essentially all of the heat and freshwater transports.
Show less
Date Issued: 2016-11
Identifier: FSU_libsubv1_wos_000386205900009, 10.1175/JCLI-D-15-0798.1
Format: Citation

Title: An Assessment of Multimodel Simulations for the Variability of Western North Pacific Tropical Cyclones and Its Association with ENSO.
Creator: Han, Rongqing, Wang, Hui, Hu, Zeng-Zhen, Kumar, Arun, Li, Weijing, Long, Lindsey N., Schemm, Jae-Kyung E., Peng, Peitao, Wang, Wanqiu, Si, Dong, Jia, Xiaolong, Zhao, Ming,...
Show moreHan, Rongqing, Wang, Hui, Hu, Zeng-Zhen, Kumar, Arun, Li, Weijing, Long, Lindsey N., Schemm, Jae-Kyung E., Peng, Peitao, Wang, Wanqiu, Si, Dong, Jia, Xiaolong, Zhao, Ming, Vecchi, Gabriel A., Larow, Timothy E., Lim, Young-Kwon, Schubert, Siegfried D., Camargo, Suzana J., Henderson, Naomi, Jonas, Jeffrey A., Walsh, Kevin J. E.
Show less
Abstract/Description: An assessment of simulations of the interannual variability of tropical cyclones (TCs) over the western North Pacific (WNP) and its association with El Nino-Southern Oscillation (ENSO), as well as a subsequent diagnosis for possible causes of model biases generated from simulated large-scale climate conditions, are documented in the paper. The model experiments are carried out by the Hurricane Work Group under the U.S. Climate Variability and Predictability Research Program (CLIVAR) using...
Show moreAn assessment of simulations of the interannual variability of tropical cyclones (TCs) over the western North Pacific (WNP) and its association with El Nino-Southern Oscillation (ENSO), as well as a subsequent diagnosis for possible causes of model biases generated from simulated large-scale climate conditions, are documented in the paper. The model experiments are carried out by the Hurricane Work Group under the U.S. Climate Variability and Predictability Research Program (CLIVAR) using five global climate models (GCMs) with a total of 16 ensemble members forced by the observed sea surface temperature and spanning the 28-yr period from 1982 to 2009. The results show GISS and GFDL model ensemble means best simulate the interannual variability of TCs, and the multimodel ensemble mean (MME) follows. Also, the MME has the closest climate mean annual number of WNP TCs and the smallest root-mean-square error to the observation. Most GCMs can simulate the interannual variability of WNP TCs well, with stronger TC activities during two types of El Nino-namely, eastern Pacific (EP) and central Pacific (CP) El Nino-and weaker activity during La Nina. However, none of the models capture the differences in TC activity between EP and CP El Nino as are shown in observations. The inability of models to distinguish the differences in TC activities between the two types of El Nino events may be due to the bias of the models in response to the shift of tropical heating associated with CP El Nino.
Show less
Date Issued: 2016-09-15
Identifier: FSU_libsubv1_wos_000383828300001, 10.1175/JCLI-D-15-0720.1
Format: Citation

Title: Contribution of Monthly and Regional Rainfall to the Strength of Indian Summer Monsoon.
Creator: Zheng, Yangxing, Ali, M. M., Bourassa, Mark A.
Abstract/Description: Indian summer monsoon rainfall (ISMR; June September) has both temporal and spatial variability causing floods and droughts in different seasons and locations, leading to a strong or weak monsoon. Here, the authors present the contribution of all-India monthly, seasonal, and regional rainfall to the ISMR, with an emphasis on the strong and weak monsoons. Here, regional rainfall is restricted to the seasonal rainfall over four regions defined by the India Meteorological Department (IMD)...
Show moreIndian summer monsoon rainfall (ISMR; June September) has both temporal and spatial variability causing floods and droughts in different seasons and locations, leading to a strong or weak monsoon. Here, the authors present the contribution of all-India monthly, seasonal, and regional rainfall to the ISMR, with an emphasis on the strong and weak monsoons. Here, regional rainfall is restricted to the seasonal rainfall over four regions defined by the India Meteorological Department (IMD) primarily for the purpose of forecasting regional rainfall: northwest India (NWI), northeast India (NEI), central India (CI), and south peninsula India (SPIN). In this study, two rainfall datasets provided by IMD are used: 1) all-India monthly and seasonal (June September) rainfall series for the entire Indian subcontinent as well as seasonal rainfall series for the four homogeneous regions for the period 1901-2013 and 2) the latest daily gridded rainfall data for the period 1951-2014, which is used for assessment at the extent to which the four regions are appropriate for the intended purpose. Rainfall during July August contributes the most to the total seasonal rainfall, regardless of whether it is a strong or weak monsoon. Although NEI has the maximum area-weighted rainfall, its contribution is the least toward determining a strong or weak monsoon. It is the rainfall in the remaining three regions (NWI, CI, and SPIN) that controls whether an ISMR is strong or weak. Compared to monthly rainfall, regional rainfall dominates the strong or weak rainfall periods.
Show less
Date Issued: 2016-09
Identifier: FSU_libsubv1_wos_000383923300001, 10.1175/MWR-D-15-0318.1
Format: Citation

Title: Working with Climate Projections to Estimate Disease Burden: Perspectives from Public Health..
Creator: Conlon, Kathryn C, Kintziger, Kristina W, Jagger, Meredith, Stefanova, Lydia, Uejio, Christopher K, Konrad, Charles
Abstract/Description: There is interest among agencies and public health practitioners in the United States (USA) to estimate the future burden of climate-related health outcomes. Calculating disease burden projections can be especially daunting, given the complexities of climate modeling and the multiple pathways by which climate influences public health. Interdisciplinary coordination between public health practitioners and climate scientists is necessary for scientifically derived estimates. We describe a...
Show moreThere is interest among agencies and public health practitioners in the United States (USA) to estimate the future burden of climate-related health outcomes. Calculating disease burden projections can be especially daunting, given the complexities of climate modeling and the multiple pathways by which climate influences public health. Interdisciplinary coordination between public health practitioners and climate scientists is necessary for scientifically derived estimates. We describe a unique partnership of state and regional climate scientists and public health practitioners assembled by the Florida Building Resilience Against Climate Effects (BRACE) program. We provide a background on climate modeling and projections that has been developed specifically for public health practitioners, describe methodologies for combining climate and health data to project disease burden, and demonstrate three examples of this process used in Florida.
Show less
Date Issued: 2016-08-09
Identifier: FSU_pmch_27517942, 10.3390/ijerph13080804, PMC4997490, 27517942, 27517942, ijerph13080804
Format: Citation

Title: The oceanic influence on the rainy season of Peninsular Florida.
Creator: Misra, Vasubandhu, Mishra, Akhilesh
Abstract/Description: In this study we show that the robust surface ocean currents around Peninsular Florida, namely, the Loop and the Florida Currents, affect the terrestrial wet season of Peninsular Florida. We show this through two novel regional coupled ocean-atmosphere models with different bathymetries that dislocate and modulate the strength of these currents and thereby affect the overlying sea surface temperature (SST) and upper ocean heat content. This study show that a weaker current system produces...
Show moreIn this study we show that the robust surface ocean currents around Peninsular Florida, namely, the Loop and the Florida Currents, affect the terrestrial wet season of Peninsular Florida. We show this through two novel regional coupled ocean-atmosphere models with different bathymetries that dislocate and modulate the strength of these currents and thereby affect the overlying sea surface temperature (SST) and upper ocean heat content. This study show that a weaker current system produces colder coastal SSTs along the Atlantic coast of Florida that reduces the length of the wet season and the total seasonal accumulation of precipitation over Peninsular Florida relative to the regional climate model simulation, in which these currents are stronger. The moisture budget reveals that as a result of these forced changes to the temperature of the upper coastal Atlantic Ocean, overlying surface evaporation and atmospheric convection is modulated. This consequently changes the moisture flux convergence leading to the modulation of the terrestrial wet season rainfall over Peninsular Florida that manifests in changes in the length and distribution of daily rain rate of the wet season. The results of this study have implications on interpreting future changes to hydroclimate of Peninsular Florida owing to climate change and low-frequency changes to the Atlantic meridional overturning circulation that comprises the Loop and the Florida Currents as part of its upper branch. he season
Show less
Date Issued: 2016-07-16
Identifier: FSU_libsubv1_wos_000380730500012, 10.1002/2016JD024824
Format: Citation

Title: The sensitivity of southeastern United States climate to varying irrigation vigor.
Creator: Selman, Christopher, Misra, Vasubandhu
Abstract/Description: Four regional climate model runs centered on the Southeast United States (SEUS) assuming a crop growing season of May through October are irrigated at 25% (IRR25), 50% (IRR50), 75% (IRR75), and 100% (IRR100) of the root zone porosity to assess the sensitivity of the SEUS climate to irrigation. A fifth run, assuming no irrigation (CTL), is used as the basis for comparison. Across all IRR runs, it is found that there is a general reduction in seasonal mean precipitation over the irrigated cells...
Show moreFour regional climate model runs centered on the Southeast United States (SEUS) assuming a crop growing season of May through October are irrigated at 25% (IRR25), 50% (IRR50), 75% (IRR75), and 100% (IRR100) of the root zone porosity to assess the sensitivity of the SEUS climate to irrigation. A fifth run, assuming no irrigation (CTL), is used as the basis for comparison. Across all IRR runs, it is found that there is a general reduction in seasonal mean precipitation over the irrigated cells relative to CTL. This manifests as an increase in dry (0-1mm/d) days and reduction in>1mm/d rainfall events. A comparative moisture budget reveals that area-averaged precipitation over the irrigated cells displays a reduction in precipitation and runoff in IRR100 with a weaker reduction in IRR25. This is despite an increase in vertically integrated moisture convergence and local evaporation. We find that irrigation increases the lower atmospheric stability, which in turn reduces the convective rainfall over the irrigated areas. Seasonally averaged temperatures reduce over irrigated areas, with the intensity of the reduction increasing with irrigation vigor. This is largely attributed to a repartitioning of sensible heat flux into latent heat flux. There is also, however, a small increase of heat flow to deeper soil layers. Precipitation ahead of transient cold fronts is also reduced by irrigation as they pass over irrigated cells, owing to the increased stability in the lower troposphere. The intensity of this precipitation reduction becomes more intense as irrigation vigor increases. Lastly, heat waves in the SEUS are reduced in intensity over irrigated cells.
Show less
Date Issued: 2016-07-16
Identifier: FSU_libsubv1_wos_000380730500007, 10.1002/2016JD025002
Format: Citation

Title: Characterizing the onset and demise of the Indian summer monsoon.
Creator: Noska, Ryne, Misra, Vasubandhu
Abstract/Description: An objective index of the onset and demise of the Indian summer monsoon (ISM) is introduced. This index has the advantage of simplicity by using only one variable, which is the spatially averaged all-India rainfall, a reliably observed quantity for more than a century. The proposed onset index is shown to be insensitive to all historic false onsets. By definition, now the seasonal mean rainfall anomalies become a function of variations in onset and demise dates, rendering their monitoring to...
Show moreAn objective index of the onset and demise of the Indian summer monsoon (ISM) is introduced. This index has the advantage of simplicity by using only one variable, which is the spatially averaged all-India rainfall, a reliably observed quantity for more than a century. The proposed onset index is shown to be insensitive to all historic false onsets. By definition, now the seasonal mean rainfall anomalies become a function of variations in onset and demise dates, rendering their monitoring to be very meaningful. This new index provides a comprehensive representation of the seasonal evolution of the ISM by capturing the corresponding changes in large-scale dynamic and thermodynamic variables. We also show that the interannual variability of the onset date of the ISM is associated with El Nino-Southern Oscillation (ENSO) with early (late) onsets preceded by cold (warm) ENSO.
Show less
Date Issued: 2016-05-16
Identifier: FSU_libsubv1_wos_000378339200057, 10.1002/2016GL068409
Format: Citation

Title: Impact of Parameterized Internal Wave Drag on the Semidiurnal Energy Balance in a Global Ocean Circulation Model.
Creator: Buijsman, Maarten C., Ansong, Joseph K., Arbic, Brian K., Richman, James G., Shriver, Jay F., Timko, Patrick G., Wallcraft, Alan J., Whalen, Caitlin B., Zhao, ZhongXiang
Abstract/Description: The effects of a parameterized linear internal wave drag on the semidiurnal barotropic and baroclinic energetics of a realistically forced, three-dimensional global ocean model are analyzed. Although the main purpose of the parameterization is to improve the surface tides, it also influences the internal tides. The relatively coarse resolution of the model of similar to 8 km only permits the generation and propagation of the first three vertical modes. Hence, this wave drag parameterization...
Show moreThe effects of a parameterized linear internal wave drag on the semidiurnal barotropic and baroclinic energetics of a realistically forced, three-dimensional global ocean model are analyzed. Although the main purpose of the parameterization is to improve the surface tides, it also influences the internal tides. The relatively coarse resolution of the model of similar to 8 km only permits the generation and propagation of the first three vertical modes. Hence, this wave drag parameterization represents the energy conversion to and the subsequent breaking of the unresolved high modes. The total tidal energy input and the spatial distribution of the barotropic energy loss agree with the Ocean Topography Experiment (TOPEX)/Poseidon (TPXO) tidal inversion model. The wave drag overestimates the high-mode conversion at ocean ridges as measured against regional high-resolution models. The wave drag also damps the low-mode internal tides as they propagate away from their generation sites. Hence, it can be considered a scattering parameterization, causing more than 50% of the deep-water dissipation of the internal tides. In the near field, most of the baroclinic dissipation is attributed to viscous and numerical dissipation. The far-field decay of the simulated internal tides is in agreement with satellite altimetry and falls within the broad range of Argo-inferred dissipation rates. In the simulation, about 12% of the semidiurnal internal tide energy generated in deep water reaches the continental margins.
Show less
Date Issued: 2016-05
Identifier: FSU_libsubv1_wos_000376153100001, 10.1175/JPO-D-15-0074.1
Format: Citation

Title: Fast multidimensional ensemble empirical mode decomposition for the analysis of big spatio-temporal datasets.
Creator: Wu, Zhaohua, Feng, Jiaxin, Qiao, Fangli, Tan, Zhe-Min
Abstract/Description: In this big data era, it is more urgent than ever to solve two major issues: (i) fast data transmission methods that can facilitate access to data from non-local sources and (ii) fast and efficient data analysis methods that can reveal the key information from the available data for particular purposes. Although approaches in different fields to address these two questions may differ significantly, the common part must involve data compression techniques and a fast algorithm. This paper...
Show moreIn this big data era, it is more urgent than ever to solve two major issues: (i) fast data transmission methods that can facilitate access to data from non-local sources and (ii) fast and efficient data analysis methods that can reveal the key information from the available data for particular purposes. Although approaches in different fields to address these two questions may differ significantly, the common part must involve data compression techniques and a fast algorithm. This paper introduces the recently developed adaptive and spatio-temporally local analysis method, namely the fast multidimensional ensemble empirical mode decomposition (MEEMD), for the analysis of a large spatio-temporal dataset. The original MEEMD uses ensemble empirical mode decomposition to decompose time series at each spatial grid and then pieces together the temporal-spatial evolution of climate variability and change on naturally separated timescales, which is computationally expensive. By taking advantage of the high efficiency of the expression using principal component analysis/empirical orthogonal function analysis for spatio-temporally coherent data, we design a lossy compression method for climate data to facilitate its non-local transmission. We also explain the basic principles behind the fast MEEMD through decomposing principal components instead of original grid-wise time series to speed up computation of MEEMD. Using a typical climate dataset as an example, we demonstrate that our newly designed methods can (i) compress data with a compression rate of one to two orders; and (ii) speed-up the MEEMD algorithm by one to two orders.
Show less
Date Issued: 2016-04-13
Identifier: FSU_pmch_26953173, 10.1098/rsta.2015.0197, PMC4792406, 26953173, 26953173, rsta.2015.0197
Format: Citation

Title: A framework to quantify uncertainty in simulations of oil transport in the ocean.
Creator: Goncalves, Rafael C., Iskandarani, Mohamed, Srinivasan, Ashwanth, Thacker, W. Carlisle, Chassignet, Eric, Knio, Omar M.
Abstract/Description: An uncertainty quantification framework is developed for the DeepC Oil Model based on a nonintrusive polynomial chaos method. This allows the model's output to be presented in a probabilistic framework so that the model's predictions reflect the uncertainty in the model's input data. The new capability is illustrated by simulating the far-field dispersal of oil in a Deepwater Horizon blowout scenario. The uncertain input consisted of ocean current and oil droplet size data and the main model...
Show moreAn uncertainty quantification framework is developed for the DeepC Oil Model based on a nonintrusive polynomial chaos method. This allows the model's output to be presented in a probabilistic framework so that the model's predictions reflect the uncertainty in the model's input data. The new capability is illustrated by simulating the far-field dispersal of oil in a Deepwater Horizon blowout scenario. The uncertain input consisted of ocean current and oil droplet size data and the main model output analyzed is the ensuing oil concentration in the Gulf of Mexico. A 1331 member ensemble was used to construct a surrogate for the model which was then mined for statistical information. The mean and standard deviations in the oil concentration were calculated for up to 30 days, and the total contribution of each input parameter to the model's uncertainty was quantified at different depths. Also, probability density functions of oil concentration were constructed by sampling the surrogate and used to elaborate probabilistic hazard maps of oil impact. The performance of the surrogate was constantly monitored in order to demarcate the spacetime zones where its estimates are reliable.
Show less
Date Issued: 2016-04
Identifier: FSU_libsubv1_wos_000383462300002, 10.1002/2015JC011311
Format: Citation

Title: Applying Automated Underway Ship Observations to Numerical Model Evaluation.
Creator: Smith, Shawn R., Briggs, Kristen, Lopez, Nicolas, Kourafalou, Vassiliki
Abstract/Description: Numerical models are used widely in the oceanic and atmospheric sciences to estimate and forecast conditions in the marine environment. Herein the application of in situ observations collected by automated instrumentation on ships at sampling rates
Show moreNumerical models are used widely in the oceanic and atmospheric sciences to estimate and forecast conditions in the marine environment. Herein the application of in situ observations collected by automated instrumentation on ships at sampling rates <= 5 min is demonstrated as a means to evaluate numerical model analyses. Specific case studies use near-surface ocean observations collected by a merchant vessel, an ocean racing yacht, and select research vessels to evaluate various ocean analyses from the Hybrid Coordinate Ocean Model (HYCOM). Although some specific differences are identified between the observations and numerical model analyses, the purpose of these comparisons is to demonstrate the value of high-sampling-rate in situ observations collected on ships for numerical model evaluation.
Show less
Date Issued: 2016-03
Identifier: FSU_libsubv1_wos_000372785000001, 10.1175/JTECH-D-15-0052.1
Format: Citation

Title: Stationary mesoscale eddies, upgradient eddy fluxes, and the anisotropy of eddy diffusivity.
Creator: Lu, Jianhua, Wang, Fuchang, Liu, Hailong, Lin, Pengfei
Abstract/Description: The mesoscale eddies of which parameterization is needed in coarse-resolution ocean models include not only the transient eddies akin to baroclinic instability but also the stationary eddies associated with topography. By applying a modified Lorenz-type decomposition to the eddy-permitting Southern Ocean State Estimate, we show that the stationary mesoscale eddies contribute a significant part to the total eddy kinetic energy, eddy enstrophy, and the total eddy-induced isopycnal thickness and...
Show moreThe mesoscale eddies of which parameterization is needed in coarse-resolution ocean models include not only the transient eddies akin to baroclinic instability but also the stationary eddies associated with topography. By applying a modified Lorenz-type decomposition to the eddy-permitting Southern Ocean State Estimate, we show that the stationary mesoscale eddies contribute a significant part to the total eddy kinetic energy, eddy enstrophy, and the total eddy-induced isopycnal thickness and potential vorticity fluxes. We find that beneath middepth (about 1000 m) the upgradient eddy fluxes, or so-called "negative" eddy diffusivities, are mainly attributed to the stationary mesoscale eddies, whereas the remaining transient eddy diffusivity is positive, for which the Gent and McWilliams (1990) parameterization scheme applies well. A quantitative method of measuring the anisotropy of eddy diffusivity is presented. The effect of stationary mesoscale eddies is one of major sources responsible for the anisotropy of eddy diffusivity. We suggest that an independent parameterization scheme for stationary mesoscale eddies may be needed for coarse-resolution ocean models, although the transient eddies remain the predominant part of mesoscale eddies in the oceans.
Show less
Date Issued: 2016-01-28
Identifier: FSU_libsubv1_wos_000372056400032, 10.1002/2015GL067384
Format: Citation

Title: Greenland freshwater pathways in the sub-Arctic Seas from model experiments with passive tracers.
Creator: Dukhovskoy, Dmitry S., Myers, Paul G., Platov, Gennady, Timmermans, Mary-Louise, Curry, Beth, Proshutinsky, Andrey, Bamber, Jonathan L., Chassignet, Eric, Hu, Xianmin, Lee,...
Show moreDukhovskoy, Dmitry S., Myers, Paul G., Platov, Gennady, Timmermans, Mary-Louise, Curry, Beth, Proshutinsky, Andrey, Bamber, Jonathan L., Chassignet, Eric, Hu, Xianmin, Lee, Craig M., Somavilla, Raquel
Show less
Abstract/Description: Accelerating since the early 1990s, the Greenland Ice Sheet mass loss exerts a significant impact on thermohaline processes in the sub-Arctic seas. Surplus freshwater discharge from Greenland since the 1990s, comparable in volume to the amount of freshwater present during the Great Salinity Anomaly events, could spread and accumulate in the sub-Arctic seas, influencing convective processes there. However, hydrographic observations in the Labrador Sea and the Nordic Seas, where the Greenland...
Show moreAccelerating since the early 1990s, the Greenland Ice Sheet mass loss exerts a significant impact on thermohaline processes in the sub-Arctic seas. Surplus freshwater discharge from Greenland since the 1990s, comparable in volume to the amount of freshwater present during the Great Salinity Anomaly events, could spread and accumulate in the sub-Arctic seas, influencing convective processes there. However, hydrographic observations in the Labrador Sea and the Nordic Seas, where the Greenland freshening signal might be expected to propagate, do not show a persistent freshening in the upper ocean during last two decades. This raises the question of where the surplus Greenland freshwater has propagated. In order to investigate the fate, pathways, and propagation rate of Greenland meltwater in the sub-Arctic seas, several numerical experiments using a passive tracer to track the spreading of Greenland freshwater have been conducted as a part of the Forum for Arctic Ocean Modeling and Observational Synthesis effort. The models show that Greenland freshwater propagates and accumulates in the sub-Arctic seas, although the models disagree on the amount of tracer propagation into the convective regions. Results highlight the differences in simulated physical mechanisms at play in different models and underscore the continued importance of intercomparison studies. It is estimated that surplus Greenland freshwater flux should have caused a salinity decrease by 0.06-0.08 in the sub-Arctic seas in contradiction with the recently observed salinification (by 0.15-0.2) in the region. It is surmised that the increasing salinity of Atlantic Water has obscured the freshening signal.
Show less
Date Issued: 2016-01
Identifier: FSU_libsubv1_wos_000371432200050, 10.1002/2015JC011290
Format: Citation

Title: Estimation Of Net Surface Radiation Using Eddy Flux Tower Data Over A Tropical Mangrove Forest Of Sundarban, West Bengal.
Creator: Mahalakshmi, D. V., Paul, Arati, Dutta, D., Ali, M. M., Dadhwal, V. K., Reddy, R. Suraj, Jha, C. S., Sharma, J. R.
Abstract/Description: In this study, net surface radiation (R-n) was estimated using artificial neural network (ANN) and Linear Model (LM). Then, estimated R-n with both the models (ANN and LM) were compared with measured R-n from eddy covariance (EC) flux tower. The routinely measured meteorological variables namely air temperature, relative humidity and wind velocity were used as input to the ANN and global solar radiation as input to the LM. All the input data are from the EC flux tower. Sensitivity analysis of...
Show moreIn this study, net surface radiation (R-n) was estimated using artificial neural network (ANN) and Linear Model (LM). Then, estimated R-n with both the models (ANN and LM) were compared with measured R-n from eddy covariance (EC) flux tower. The routinely measured meteorological variables namely air temperature, relative humidity and wind velocity were used as input to the ANN and global solar radiation as input to the LM. All the input data are from the EC flux tower. Sensitivity analysis of ANN with all the meteorological variables is carried out by excluding one by one meteorological variable. The validation results demonstrated that, ANN and LM estimated R-n values were in good agreement with the measured values, with root mean square error (RMSE) varying between 21.63 W/m(2) and 34.94 W/m(2), mean absolute error (MAE) between 17.93 W/m2 and 22.28 W/m(2) and coefficient of residual mass (CRM) between -0.007 and -0.04 respectively. Further we have computed modelling efficiency (0.97 for ANN and 0.99 for LM) and coefficient of determination (R-2 = 0.97 for ANN and 0.99 for LM) for both the models. Even though both the models could predict R-n successfully, ANN was better in terms of minimum number of routinely measured meteorological variables as input. The results of the ANN sensitivity analysis indicated that air temperatuere is the more important parameter followed by relative humidity, wind speed and wind direction.
Show less
Date Issued: 2016
Identifier: FSU_libsubv1_wos_000381162400001, 10.15233/gfz.2016.33.5
Format: Citation

Title: Heat content of the Arabian Sea Mini Warm Pool is increasing.
Creator: Nagamani, P. V., Ali, M. M., Goni, G. J., Bhaskar, T. V. S. Udaya, McCreary, J. P., Weller, R. A., Rajeevan, M., Krishna, V. V. Gopala, Pezzullo, J. C.
Abstract/Description: Sea surface temperature in the Arabian Sea Mini Warm Pool has been suggested to be one of the factors that affects the Indian summer monsoon. In this paper, we analyze the annual ocean heat content (OHC) of this region during 1993-2010, using in situ data, satellite observations, and a model simulation. We find that OHC increases significantly in the region during this period relative to the north Indian Ocean, and propose that this increase could have caused the decrease in Indian Summer...
Show moreSea surface temperature in the Arabian Sea Mini Warm Pool has been suggested to be one of the factors that affects the Indian summer monsoon. In this paper, we analyze the annual ocean heat content (OHC) of this region during 1993-2010, using in situ data, satellite observations, and a model simulation. We find that OHC increases significantly in the region during this period relative to the north Indian Ocean, and propose that this increase could have caused the decrease in Indian Summer Monsoon Rainfall that occurred at the same time.
Show less
Date Issued: 2016-01
Identifier: FSU_libsubv1_wos_000369737200007, 10.1002/asl.596
Format: Citation

Title: Analysis methods for characterizing salinity variability from multivariate time series applied to the Apalachicola Bay estuary.
Creator: Morey, Steven, Dukhovskoy, Dmitry
Abstract/Description: Statistical analysis methods are developed to quantify the impacts of multiple forcing variables on the hydrographic variability within an estuary instrumented with an enduring observational system. The methods are applied to characterize the salinity variability within Apalachicola Bay, a shallow multiple-inlet estuary along the northeastern Gulf of Mexico coast. Thirteen-year multivariate time series collected by the National Estuary Research Reserve at three locations within the bay are...
Show moreStatistical analysis methods are developed to quantify the impacts of multiple forcing variables on the hydrographic variability within an estuary instrumented with an enduring observational system. The methods are applied to characterize the salinity variability within Apalachicola Bay, a shallow multiple-inlet estuary along the northeastern Gulf of Mexico coast. Thirteen-year multivariate time series collected by the National Estuary Research Reserve at three locations within the bay are analyzed to determine how the estuary responds to variations in external forcing mechanisms, such as freshwater discharge, precipitation, tides and local winds, at multiple time scales. The analysis methods are used to characterize the estuarine variability under differing flow regimes of the Apalachicola River, a managed waterway, with particular focus on extreme events and scales of variability that are critical to local ecosystems. Multivariate statistical models are applied that describe the salinity response to winds from multiple directions, river flow, and precipitation at daily, weekly, and monthly time scales to understand the response of the estuary under different climate regimes. Results show that the salinity is particularly sensitive to river discharge and wind magnitude and direction, with local precipitation being largely unimportant. Applying statistical analyses with conditional sampling quantifies how the likelihoods of high salinity and long duration high salinity events, conditions of critical importance to estuarine organisms, change given the state of the river flow. Intraday salinity range is shown to be negatively correlated with the salinity, and correlated with river discharge rate.
Show less
Date Issued: 2012
Identifier: FSU_migr_coaps_pubs-0047, 10.1175/JTECH-D-11-00136.1
Format: Citation

Title: Evaluation of dynamically downscaled reanalysis precipitation data for hydrological application in the southeast United States.
Creator: Bastola, Satish, Misra, Vasubandhu
Abstract/Description: Skillful and reliable precipitation data is essential for seasonal hydrologic forecasting, and generation of hydrological data. Though output from dynamic downscaling methods is used for hydrological application, the existence of systematic errors in dynamically downscaled data adversely affects the skill of hydrologic forecasting. This study evaluates the precipitation data derived by dynamically downscaling the global atmospheric reanalysis data by propagating them through three...
Show moreSkillful and reliable precipitation data is essential for seasonal hydrologic forecasting, and generation of hydrological data. Though output from dynamic downscaling methods is used for hydrological application, the existence of systematic errors in dynamically downscaled data adversely affects the skill of hydrologic forecasting. This study evaluates the precipitation data derived by dynamically downscaling the global atmospheric reanalysis data by propagating them through three hydrological models. Hydrological models are calibrated for 28 basins located in the southeast United States (U.S.) that is minimally affected by human intervention. Calibrated hydrological models are forced with five different types of datasets: global (NCEP R2 and ERA40) at their native resolution; dynamically downscaled; synthetically generated; bias-corrected, dynamically downscaled and bias-corrected global reanalysis. Our study indicates that over the 28 watersheds in the southeast U.S., the simulated hydrological response to the biascorrected dynamically downscaled data is superior. In comparison to synthetically generated meteorological forcing, the dynamically downscaled data result in more realistic hydrological simulations. Therefore, we conclude that dynamical downscaling, although resource intensive, is better suited for hydrological simulation in the southeast U.S.
Show less
Date Issued: 2012
Identifier: FSU_migr_coaps_pubs-0057
Format: Citation

Title: High-latitude ocean and sea ice surface fluxes: requirements and challenges for climate research.
Creator: Bourassa, Mark, Gille, Sarah Tragler, Bitz, Cecilia M., Carlson, David, Cerovecki, Ivana, Cronin, Meghan, Drennan, Will, Fairall, Chris, Hoffman, Ross, Magusdottir, Gudrun,...
Show moreBourassa, Mark, Gille, Sarah Tragler, Bitz, Cecilia M., Carlson, David, Cerovecki, Ivana, Cronin, Meghan, Drennan, Will, Fairall, Chris, Hoffman, Ross, Magusdottir, Gudrun, Pinker, Rachel, Renfrew, Ian, Serreze, Mark C., Speer, Kevin G. (Kevin George), Talley, Lynne D., Wick, Gary
Show less
Abstract/Description: Improving knowledge of air-sea exchanges of heat, momentum, fresh water, and gases is critical to understanding climate, and this is particularly true in high-latitude regions, where anthropogenic climate change is predicted to be exceptionally rapid. However, observations of these fluxes are extremely scarce in the Arctic, the Southern Ocean, and the Antarctic marginal seas. High winds, high sea state, extreme cold temperatures, seasonal sea ice, and the remoteness of the regions all...
Show moreImproving knowledge of air-sea exchanges of heat, momentum, fresh water, and gases is critical to understanding climate, and this is particularly true in high-latitude regions, where anthropogenic climate change is predicted to be exceptionally rapid. However, observations of these fluxes are extremely scarce in the Arctic, the Southern Ocean, and the Antarctic marginal seas. High winds, high sea state, extreme cold temperatures, seasonal sea ice, and the remoteness of the regions all conspire to make observations difficult to obtain. Annually averaged heat-flux climatologies can differ by more than their means, and in many cases there is no clear consensus about which flux products are most reliable. Although specific flux accuracy requirements for climate research vary depending on the application, in general fluxes would better represent high-latitude processes if wind stresses achieved 0.01Nm-2 accuracy at high wind speed and if heat fluxes achieved 10 W m-2 accuracy (averaged over several days) with 25 km grid spacing. Improvements in flux estimates will require a combination of efforts, including a concerted plan to make better use of ships of opportunity to collect meteorological data, targeted efforts to deploy a few flux moorings in high-wind regions, and improved satellite retrievals of flux-related variables.
Show less
Date Issued: 2012
Identifier: FSU_migr_coaps_pubs-0017
Format: Citation

Title: California reanalysis downscaling at 10 km using an ocean-atmosphere coupled regional model system.
Creator: Li, Haiqin, Kanamitsu, Masao, Hong, Song-You
Abstract/Description: A fully coupled regional downscaling system for both the Regional Spectral Model (RSM) for atmosphere and the Regional Ocean Modeling System (ROMS) for the ocean was developed for the purpose of downscaling observed analysis or global model outputs. The two models share the same grid and resolution with efficient parallelization through the use of dual message passing interfaces. Coupled downscaling was performed using historical Simple Ocean Data Assimilation (SODA) oceanic reanalysis and...
Show moreA fully coupled regional downscaling system for both the Regional Spectral Model (RSM) for atmosphere and the Regional Ocean Modeling System (ROMS) for the ocean was developed for the purpose of downscaling observed analysis or global model outputs. The two models share the same grid and resolution with efficient parallelization through the use of dual message passing interfaces. Coupled downscaling was performed using historical Simple Ocean Data Assimilation (SODA) oceanic reanalysis and NCEP/DOE (R-2) atmospheric reanalysis in order to study the impact of coupling on the regional scale atmospheric analysis. The results were subsequently compared with the uncoupled downscaling forced by the prescribed observed sea surface temperature (SST). An evaluation of the SST and ocean current from the coupled experiment yielded realistic small-scale oceanic features that are nearly absent in the oceanic reanalysis. Upwelling over the California coast is well resolved and comparable to findings obtained from high-resolution observations. The coupling impact on the atmospheric circulation mainly modulates the near surface atmospheric variables when compared to the simulation conducted without coupling. The duration of the Catalina Eddy detected in the coupled experiment increased by about 6.5% when compared to that in the uncoupled experiment. The offshore land breeze is enhanced by about 10%, whereas the change in the onshore sea breeze is very small during the summer.
Show less
Date Issued: 2012
Identifier: FSU_migr_coaps_pubs-0059, 10.1029/2011JD017372
Format: Citation

Title: Understanding wet season variations over Florida.
Creator: Misra, Vasubandhu, DiNapoli, Steven
Abstract/Description: The wet season of Florida is well defined and is invariably centered in the boreal summer season of June–July–August. In this observational study we objectively define the Length of the Wet Season (LOWS) for Florida and examine its variations with respect to El Niño and the Southern Oscillation (ENSO) and the Atlantic Warm Pool (AWP). Our study reveals that ENSO variability has a profound influence on the LOWS especially over south Florida and parts of panhandle Florida prior to 1976. In the...
Show moreThe wet season of Florida is well defined and is invariably centered in the boreal summer season of June–July–August. In this observational study we objectively define the Length of the Wet Season (LOWS) for Florida and examine its variations with respect to El Niño and the Southern Oscillation (ENSO) and the Atlantic Warm Pool (AWP). Our study reveals that ENSO variability has a profound influence on the LOWS especially over south Florida and parts of panhandle Florida prior to 1976. In the post-1976 era the influence of ENSO has significantly diminished. Our results show that in this pre-1976 era, warm (cold) ENSO events in the boreal winter are followed by long (short) LOWS over the region. This variation is consistent with warm (cold) ENSO events influencing early (late) onset of the wet season in the region. There is significant relationship of the LOWS in south and northeast Florida with the variation of the AWP. Unlike the teleconnection with ENSO the relationship of the demise of the wet season with AWP is stronger in the post-1976 period compared to the pre-1976 period. Furthermore the variability of the LOWS has increased in the post-1976 period.
Show less
Date Issued: 2012
Identifier: FSU_migr_coaps_pubs-0056, 10.1007/s00382-012-1382-4
Format: Citation

Title: Generation of mesoscale eddies in the lee of the Hawaiian Islands.
Creator: Jia, Yinglai, Calil, P., Chassignet, E., Metzger, E., Potemra, J., Richards, K., Wallcraft, Alan J.
Abstract/Description: The ocean west of the main Hawaiian Islands is characterized by enhanced eddy kinetic energy arising from the abundance of locally generated mesoscale eddies, most frequently in the area west of the island of Hawaii. Two mechanisms of eddy generation in the wake of an island are examined with numerical model experiments. The first, eddy generation and shedding by an oceanic flow around an oceanic barrier, requires the existence of strong westward flows to the north and south of the island of...
Show moreThe ocean west of the main Hawaiian Islands is characterized by enhanced eddy kinetic energy arising from the abundance of locally generated mesoscale eddies, most frequently in the area west of the island of Hawaii. Two mechanisms of eddy generation in the wake of an island are examined with numerical model experiments. The first, eddy generation and shedding by an oceanic flow around an oceanic barrier, requires the existence of strong westward flows to the north and south of the island of Hawaii. Model solutions show such westward flows and generation of eddies by these flows although the intensity of the eddies and the generation frequency are much lower than that derived from altimetry. As a result, these eddies contribute an insignificant amount of eddy kinetic energy in the region. The second, eddy generation and shedding by an atmospheric flow around an atmospheric barrier, is based on oceanic upwelling and downwelling induced by surface wind shear, effectively introducing sinks and sources to the ocean interior. Previous idealized modeling studies have shown that oceanic eddies can be generated by sufficiently strong forcing (source or sink), providing an explanation why eddy occurrences in the lee of the island of Hawaii coincide with periods of strong trade winds. Eddy generation characteristics in the model experiments are consistent with this mechanism in terms of time of occurrence, strength and the resulting eddy kinetic energy. Major discrepancies are in eddy propagation and therefore eddy distribution in the regional domain due to the complex nature of eddy-eddy interactions.
Show less
Date Issued: 2011
Identifier: FSU_migr_coaps_pubs-0051, 10.1029/2011JC007305
Format: Citation

Title: High-resolution satellite surface latent heat fluxes in North Atlantic hurricanes.
Creator: Liu, Jiping, Curry, Judith A., Clayson, Carol Anne, Bourassa, Mark
Abstract/Description: This study presents a new high-resolution satellite-derived ocean surface flux product, XSeaFlux, which is evaluated for its potential use in hurricane studies. The XSeaFlux employs new satellite data sets using improved retrieval methods, and uses a new bulk flux algorithm formulated for high wind conditions. The XSeaFlux latent heat flux (LHF) performs much better than the existing numerical weather prediction reanalysis and satellite-derived flux products in a comparison with measurements...
Show moreThis study presents a new high-resolution satellite-derived ocean surface flux product, XSeaFlux, which is evaluated for its potential use in hurricane studies. The XSeaFlux employs new satellite data sets using improved retrieval methods, and uses a new bulk flux algorithm formulated for high wind conditions. The XSeaFlux latent heat flux (LHF) performs much better than the existing numerical weather prediction reanalysis and satellite-derived flux products in a comparison with measurements from the Coupled Boundary Layer Air-Sea Transfer (CBLAST) field experiment. Also, the XSeaFlux shows well-organized LHF structure and large LHF values in response to hurricane conditions relative to the other flux products. The XSeaFlux data set is used to interpret details of the ocean surface LHF for selected North Atlantic hurricanes. Analysis of the XSeaFlux data set suggests that ocean waves, sea spray, and cold wake have substantial impacts on LHF associated with the hurricanes.
Show less
Date Issued: 2011
Identifier: FSU_migr_coaps_pubs-0023, 10.1175/2011MWR3548.1
Format: Citation

Title: Climate scenarios: a Florida-centric view.
Creator: Misra, Vasubandhu, Carlson, E., Craig, R., Enfield, D.
Abstract/Description: The purpose of this document is to provide an informed opinion on future climate scenarios relevant to Florida. It offers a primer on Florida's vulnerabilities to climate variability and change. The document is an excellent compilation of diverse viewpoints on future climate projection. It implores the readers to be cognizant of the associated uncertainty but not to use that as an excuse for inaction in climate adaptation and mitigation. Experts in diverse fields employed in institutions...
Show moreThe purpose of this document is to provide an informed opinion on future climate scenarios relevant to Florida. It offers a primer on Florida's vulnerabilities to climate variability and change. The document is an excellent compilation of diverse viewpoints on future climate projection. It implores the readers to be cognizant of the associated uncertainty but not to use that as an excuse for inaction in climate adaptation and mitigation. Experts in diverse fields employed in institutions across Florida have contributed to this document and provided candid and informed assessments of future climate variation and change. The uniqueness of this document is that it broadens the discussion of a rather restrictive sounding title like "climate scenarios" to involve experts in sociology, environmental law, and economics, in addition to oceanography and meteorology. The earth's climate is a very complex system. Climate is intimately interrelated to many components of the earth system. However, climate is not limited to these interactions alone. It also includes the modulation of these interactions by external factors such as anthropogenic influence (or interference), volcanic eruptions, changes in solar activity, and changing planetary factors like orbital eccentricity, obliquity, and precession. Against this backdrop of complexity, this paper has tried to distill the information that is relevant to Florida. It is well understood that climate has no borders, and yet we focus here on Florida because of the huge demand for locally applicable information on climate change and variation. Therefore, time and again throughout this paper the impact of remote climate variations and change on Florida is emphasized. Finally this document provides some initial suggestions to further fortify our understanding of the impact of global climate change on Florida. The caveat however, is that these fledgling suggestions will have to be further molded by a developing synergy between the federal, state, private stakeholders and university researchers.
Show less
Date Issued: 2011
Identifier: FSU_migr_coaps_pubs-0014
Format: Citation

Title: Climate Data Issues from an Oceanographic Remote Sensing Perspective.
Creator: Katsaros, Kristina, Bentamy, Abderrahim, Bourassa, Mark, Ebuchi, Naoto, Gower, James, Liu, W., Vignudelli, Stefano
Abstract/Description: In this chapter we review several climatologically important variables with a history of observation from spaceborne platforms. These include sea surface temperature and wind vectors, altimetric estimates of sea surface height, energy and water vapor fluxes at the sea surface, precipitation over the ocean, and ocean color. We then discuss possible improvements in sampling for climate and climate change definition. Issues of consistency of different data sources, archiving and distribution of...
Show moreIn this chapter we review several climatologically important variables with a history of observation from spaceborne platforms. These include sea surface temperature and wind vectors, altimetric estimates of sea surface height, energy and water vapor fluxes at the sea surface, precipitation over the ocean, and ocean color. We then discuss possible improvements in sampling for climate and climate change definition. Issues of consistency of different data sources, archiving and distribution of these types of data are discussed. The practical prospect of immediate international coordination through the concept of virtual constellations is discussed and applauded.
Show less
Date Issued: 2011
Identifier: FSU_migr_coaps_pubs-0062, 10.1007/978-3-642-16541-2_2
Format: Citation

Title: On the variability of the Mediterranean Outflow Water in the Atlantic Ocean from 1948 to 2006.
Creator: Bozec, Alexandra, Lozier, M., Chassignet, E., Halliwell, George
Abstract/Description: Recent work has shown that variability in the properties and/or transport of Mediterranean Seawaters spilling across the Strait of Gibraltar into the North Atlantic have had little impact on the variability of Mediterranean Outflow Water (MOW) in the that basin over the past fifty years. Here we investigate whether circulation changes are the dominant source of MOW variability in the North Atlantic between 1948 and 2006. Using a 1/3° North Atlantic configuration of the HYbrid Coordinate Ocean...
Show moreRecent work has shown that variability in the properties and/or transport of Mediterranean Seawaters spilling across the Strait of Gibraltar into the North Atlantic have had little impact on the variability of Mediterranean Outflow Water (MOW) in the that basin over the past fifty years. Here we investigate whether circulation changes are the dominant source of MOW variability in the North Atlantic between 1948 and 2006. Using a 1/3° North Atlantic configuration of the HYbrid Coordinate Ocean Model combined with the Marginal Sea Boundary Condition model, two simulations forced by either climatological or interannual atmospheric fields are performed. The interannual simulation reproduces the observed MOW variability without Mediterranean Seawater changes. Thus, we conclude that MOW variability in the last 60 years is a consequence of circulation changes in the North Atlantic. A series of simulations that separate the mechanical effect of the wind from the impact of buoyancy forcing show that MOW variability can be attributed to shifts between its dominant northward and westward pathways. The pathway shifts from predominantly northward between 1950 and 1975 to predominantly westward between 1975 and 1995 and finally back to northward after 1995. Though these pathway shifts appear to be wind-induced, the property changes are caused by the combined impact of wind and buoyancy forcing on the circulation of the North Atlantic.
Show less
Date Issued: 2011
Identifier: FSU_migr_coaps_pubs-0015, 10.1029/2011JC007191
Format: Citation

Title: Operational marine forecasters and the importance of marine forecasting.
Creator: Sullivan, D., Murphree, Tom, Rosenfield, L., Smith, S.
Abstract/Description: A major goal of the Marine Advanced Technology Education (MATE) Center is to align curriculum and program development with the needs of employers. The Center believes that graduates from MATE-affiliated educational institutions should be well informed about workforce needs and well equipped with the skills required to enter marine technical occupations. To accomplish this, one of the methods used by the MATE Center is the development and use of Knowledge and Skill Guidelines. (Knowledge and...
Show moreA major goal of the Marine Advanced Technology Education (MATE) Center is to align curriculum and program development with the needs of employers. The Center believes that graduates from MATE-affiliated educational institutions should be well informed about workforce needs and well equipped with the skills required to enter marine technical occupations. To accomplish this, one of the methods used by the MATE Center is the development and use of Knowledge and Skill Guidelines. (Knowledge and Skill Guidelines may also be referred to as Occupational Guidelines or Standards or Skill Standards.) This document represents one such resource for Operational Marine Forecasters.
Show less
Date Issued: 2011
Identifier: FSU_migr_coaps_pubs-0013
Format: Citation

Title: A proxy for high-resolution regional reanalysis for the Southeast United States: assessment of precipitation variability in dynamically downscaled reanalyses.
Creator: Stefanova, Lydia, Misra, Vasubandhu, Chan, Steven, Griffin, Melissa, O'Brien, James J., Smith, III, Thomas
Abstract/Description: A variety of practical applications, such as hydrological and ecological modeling, require high-resolution meteorological data sets. A crucial, yet notoriously difficult to model, component of such data sets is precipitation. Here, we present an analysis of the seasonal, subseasonal, and diurnal variability of rainfall from the COAPS Land-Atmosphere Regional Reanalysis for the Southeast at 10-km resolution (CLARReS10). Most of our analysis focuses on the representation of summertime...
Show moreA variety of practical applications, such as hydrological and ecological modeling, require high-resolution meteorological data sets. A crucial, yet notoriously difficult to model, component of such data sets is precipitation. Here, we present an analysis of the seasonal, subseasonal, and diurnal variability of rainfall from the COAPS Land-Atmosphere Regional Reanalysis for the Southeast at 10-km resolution (CLARReS10). Most of our analysis focuses on the representation of summertime subseasonal and diurnal variability. Summer precipitation in the Southeast is a particularly challenging modeling problem because of the variety of regional-scale phenomena, such as sea breeze, thunderstorms and squall lines, tropical storms, and hurricanes, which are barely resolved in coarse atmospheric reanalyses, but which contribute significantly to the hydrological budget over the region. The National Centers for Environmental Prediction (NCEP) - Department of Energy (DOE) Reanalysis II (R2) and the European Centre for Medium-Range Weather Forecast (ECMWF) 40-year Reanalysis (ERA40) have been dynamically downscaled with the NCEP/Experimental Climate Prediction Center (ECPC) Regional Spectral Model (RSM). The downscaling has been performed over the Southeast United States at a horizontal resolution of 10 km for the period 1979-2001. The resulting regional reanalyses are compared to gridded observations and station data. We find that the downscaled reanalyses show good agreement with observations in terms of both the relative seasonal distribution and the diurnal structure of precipitation. The spatial distribution of precipitation has a wet bias over most of the region. There are noticeable differences between the two simulations: CLARReS10-ERA40 (the downscaled ERA40) tends to be wetter than CLARReS10-R2 (the downscaled R2), and the diurnal precipitation maximum occurs earlier in the day in CLARReS10- ERA40
Show less
Date Issued: 2011
Identifier: FSU_migr_coaps_pubs-0027, 10.1007/s00382-011-1230-y
Format: Citation

Title: A vortex isolation and removal algorithm for numerical weather prediction model tropical cyclone applications.
Creator: Winterbottom, Henry R., Chassignet, E.
Abstract/Description: Inserting an externally defined (i.e., synthetic) tropical cyclone (TC) vortex into numerical weather prediction (NWP) model analyses requires that an existing TC vortex first be removed. Similarly, statistical-dynamical forecasting methods require that the larger-scale environmental attributes of the flow be separated (and preserved) from those on the smaller meso- and TC vortex scales. The existing operational methods to accomplish such tasks are optimized particularly for the respective...
Show moreInserting an externally defined (i.e., synthetic) tropical cyclone (TC) vortex into numerical weather prediction (NWP) model analyses requires that an existing TC vortex first be removed. Similarly, statistical-dynamical forecasting methods require that the larger-scale environmental attributes of the flow be separated (and preserved) from those on the smaller meso- and TC vortex scales. The existing operational methods to accomplish such tasks are optimized particularly for the respective models grid spacing resolution and thus are not general when applied to finer resolution analyses. Further, the existing methods often adhere to rigid assumptions regarding the size and structure of the TC. A methodology is provided in this study to overcome these limitations. This is accomplished through analyzing the features of the NWP model analysis (e.g., the variables in the vicinity of the TC) and then systematically removing the TC through the application of both a smoothing operator and a subsequent statistical evaluation of the smoothed analysis variable. The value of our methodology is determined when analyzing the results from experiments initialized from an analysis containing TCs and those initialized from analyses without the respective TCs. This methodology is also robust for it does not require a tuning of parameters relative to varying grid-spacing resolutions and may thus benefit the statistical-dynamical TC intensity prediction schemes.
Show less
Date Issued: 2011
Identifier: FSU_migr_coaps_pubs-0050, 10.1029/2011MS000088
Format: Citation

Title: A comparison of sequential assimilation schemes for ocean prediction with the HYbrid Coordinate Ocean Model (HYCOM). Part I: Twin experiments.
Creator: Srinivasan, A.
Date Issued: 2011
Identifier: FSU_migr_coaps_pubs-0022
Format: Citation

Title: The arrested Agulhas retroflection.
Creator: Nof, Doron, Zharkov, Volodymyr, Ortiz, Joseph, Paldor, Nathan, Arruda, Wilton, Chassignet, E.
Abstract/Description: Paleoceanographic proxy data indicate that the Agulhas leakage into the South Atlantic was dramatically reduced during glacial times. In our former papers, we suggested that this was due to a northward shift of the zero wind stress curl that, in turn, forced the retroflection to occur farther north, where the slant of the coastline relative to the north is steep. In the present paper, we propose that strong westerlies (0.4 Pa, implying a wind speed of ~ 12 m s-1 at zero degrees centigrade),...
Show morePaleoceanographic proxy data indicate that the Agulhas leakage into the South Atlantic was dramatically reduced during glacial times. In our former papers, we suggested that this was due to a northward shift of the zero wind stress curl that, in turn, forced the retroflection to occur farther north, where the slant of the coastline relative to the north is steep. In the present paper, we propose that strong westerlies (0.4 Pa, implying a wind speed of ~ 12 m s-1 at zero degrees centigrade), which were supposedly common during glaciations, can also arrest the leakage. This arrest occurred because the wind stress opposed the momentum flux associated with the retroflection; such an arrest did not require the retroflection to shift in latitude. We use a simple, nonlinear, "reduced gravity" model to show analytically and numerically that, under the above conditions, the eastward wind stress compensates for the zonal westward flow-force associated with the retroflection, thus avoiding the development and shedding of rings. For a nearly zonal wall, westerly winds, and small upper layer thickness along the wall, the arresting wind stress is found, theoretically, to be, τx~0.042α3/2ρf[(2fQ)3/g']1/4 where α is twice the retroflection eddy vorticity, ρ the water density, and Q the Agulhas Current volume flux; the remaining notation is conventional.
Show less
Date Issued: 2011
Identifier: FSU_migr_coaps_pubs-0053, 10.1357/002224011799849453
Format: Citation

Title: A latent heat retrieval and its effects on the intensity and structure change of Hurricane Guillermo (1997). Part I: the algorithm and observations.
Creator: Guimond, S., Bourassa, Mark, Reasor, Paul
Abstract/Description: Despite the fact that latent heating in cloud systems drives many atmospheric circulations, including tropical cyclones, little is known of its magnitude and structure, largely because of inadequate observations. In this work, a reasonably high-resolution (2 km), four-dimensional airborne Doppler radar retrieval of the latent heat of condensation/evaporation is presented for rapidly intensifying Hurricane Guillermo (1997). Several advancements in the basic retrieval algorithm are shown,...
Show moreDespite the fact that latent heating in cloud systems drives many atmospheric circulations, including tropical cyclones, little is known of its magnitude and structure, largely because of inadequate observations. In this work, a reasonably high-resolution (2 km), four-dimensional airborne Doppler radar retrieval of the latent heat of condensation/evaporation is presented for rapidly intensifying Hurricane Guillermo (1997). Several advancements in the basic retrieval algorithm are shown, including 1) analyzing the scheme within the dynamically consistent framework of a numerical model, 2) identifying algorithm sensitivities through the use of ancillary data sources, and 3) developing a precipitation budget storage term parameterization. The determination of the saturation state is shown to be an important part of the algorithm for updrafts of -5 m s -1 or less. The uncertainties in the magnitude of the retrieved heating are dominated by errors in the vertical velocity. Using a combination of error propagation and Monte Carlo uncertainty techniques, biases are found to be small, and randomly distributed errors in the heating magnitude are ~16% for updrafts greater than 5 m s -1 and ~156% for updrafts of 1 m s -1. Even though errors in the vertical velocity can lead to large uncertainties in the latent heating field for small updrafts/downdrafts, in an integrated sense the errors are not as drastic. In Part II, the impact of the retrievals is assessed by inserting the heating into realistic numerical simulations at 2-km resolution and comparing the generated wind structure to the Doppler radar observations of Guillermo.
Show less
Date Issued: 2011
Identifier: FSU_migr_coaps_pubs-0018, 10.1175/2011JAS3700.1
Format: Citation

Title: A modeling study of the interaction between the Atlantic Warm Pool, the tropical Atlantic easterlies, and the Lesser Antilles.
Creator: Chan, Steven, Misra, Vasubandhu, Smith, H.
Abstract/Description: The European Centre for Medium-Range Forecasts Reanalysis-40 and National Centers for Environmental Prediction (NCEP)/Department of Energy reanalyses are downscaled over the eastern Caribbean and Lesser Antilles using the NCEP-Scripps Regional Spectral Model for Augusts when the Atlantic Warm Pool (AWP) area is the most anomalous. The simulations show a two-way influence between the Lesser Antilles and the AWP: the islands modulate the regional atmospheric circulation, and AWP variations...
Show moreThe European Centre for Medium-Range Forecasts Reanalysis-40 and National Centers for Environmental Prediction (NCEP)/Department of Energy reanalyses are downscaled over the eastern Caribbean and Lesser Antilles using the NCEP-Scripps Regional Spectral Model for Augusts when the Atlantic Warm Pool (AWP) area is the most anomalous. The simulations show a two-way influence between the Lesser Antilles and the AWP: the islands modulate the regional atmospheric circulation, and AWP variations modulate the interannual variabilities of the islands. The Lesser Antilles introduce diurnal variations and drag to the easterlies. The presence of the islands modulates the prevalent easterlies as a result of the daytime heating of the islands and the consequent boundary layer expansion. The modulations are sensitive to the islands' size and topography. Small and flat islands act as thermal plumes, but the modulations of large and hilly islands are during the daytime as their boundary layer expands. The manifestation of the atmospheric response to the sea surface temperature (SST) anomalies over the islands is sensitive to the island orography. For most islands, the atmospheric response to the SST anomalies is reflected only during the daytime. For all 1-grid-point islands and Antigua, nighttime and dawn minimum temperatures are modulated to the same degree as the daytime maximum. For island rainfall, downscaling reduces the gross overestimations of rainfall in the reanalyses. However, our downscaling results suggest that there is room for improvement in simulating the marine surface diurnal cycle.
Show less
Date Issued: 2011
Identifier: FSU_migr_coaps_pubs-0029, 10.1029/2010JD015260
Format: Citation

Title: The influence of the Atlantic Warm Pool on Panhandle Florida Sea Breeze.
Creator: Misra, Vasubandhu, Moeller, Lauren, Stefanova, Lydia, Chan, Steven, O'Brien, James J., Smith, III, Thomas, Plant, Nathaniel
Abstract/Description: In this paper we examine the variations of the boreal summer season sea breeze circulation along the Florida panhandle coast from relatively high resolution (10 km) regional climate model integrations. The 23 year climatology (1979-2001) of the multidecadal dynamically downscaled simulations forced by the National Centers for Environmental Prediction-Department of Energy (NCEP-DOE) Reanalysis II at the lateral boundaries verify quite well with the observed climatology. The variations at...
Show moreIn this paper we examine the variations of the boreal summer season sea breeze circulation along the Florida panhandle coast from relatively high resolution (10 km) regional climate model integrations. The 23 year climatology (1979-2001) of the multidecadal dynamically downscaled simulations forced by the National Centers for Environmental Prediction-Department of Energy (NCEP-DOE) Reanalysis II at the lateral boundaries verify quite well with the observed climatology. The variations at diurnal and interannual time scales are also well simulated with respect to the observations. We show from composite analyses made from these downscaled simulations that sea breezes in northwestern Florida are associated with changes in the size of the Atlantic Warm Pool (AWP) on interannual time scales. In large AWP years when the North Atlantic Subtropical High becomes weaker and moves further eastward relative to the small AWP years, a large part of the southeast U.S. including Florida comes under the influence of relatively strong anomalous low-level northerly flow and large-scale subsidence consistent with the theory of the Sverdrup balance. This tends to suppress the diurnal convection over the Florida panhandle coast in large AWP years. This study is also an illustration of the benefit of dynamic downscaling in understanding the low-frequency variations of the sea breeze.
Show less
Date Issued: 2011
Identifier: FSU_migr_coaps_pubs-0032, 10.1029/2010JD015367
Format: Citation

Title: Dynamic downscaling of the North American Monsoon with the NCEP-Scripps Regional Spectral Model from the NCEP CFS global model.
Creator: Chan, Steven, Misra, Vasubandhu
Abstract/Description: The June-September (JJAS) 2000-2007 NCEP coupled Climate Forecasting System (CFS) global hindcasts are downscaled over the North and South American continents with the NCEP-Scripps Regional Spectral Model (RSM) with anomaly nesting (AN) and without bias correction (control). A diagnosis of the North American Monsoon (NAM) in CFS and RSM hindcasts is presented here. RSM reduces errors caused by coarse resolution, but is unable to address larger scale CFS errors even with bias correction. CFS...
Show moreThe June-September (JJAS) 2000-2007 NCEP coupled Climate Forecasting System (CFS) global hindcasts are downscaled over the North and South American continents with the NCEP-Scripps Regional Spectral Model (RSM) with anomaly nesting (AN) and without bias correction (control). A diagnosis of the North American Monsoon (NAM) in CFS and RSM hindcasts is presented here. RSM reduces errors caused by coarse resolution, but is unable to address larger scale CFS errors even with bias correction. CFS has relatively weak Great Plains and Gulf of California low-level jets. Low-level jets are strengthened from downscaling, especially after AN bias correction. The RSM NAM hydroclimate shares similar flaws with CFS with problematic diurnal and seasonal variability. Flaws in both diurnal and monthly variability are forced by erroneous convection-forced divergence outside the monsoon core region in eastern and southern Mexico. NCEP Reanalysis shows significant seasonal variability errors, and AN shows little improvement in regional scale flow errors. Our results suggest extreme caution must be taken when the correction is applied relative to reanalyses. Analysis also shows North American Regional Reanalysis NAM seasonal variability has benefited from precipitation data assimilation, but many questions remain concerning NARR's representation of NAM.
Show less
Date Issued: 2011
Identifier: FSU_migr_coaps_pubs-0030, 10.1175/2010JCLI3593.1
Format: Citation

Title: Recent historically low global tropical cyclone activity.
Creator: Maue, Ryan Nicholas
Abstract/Description: Tropical cyclone accumulated cyclone energy (ACE) has exhibited strikingly large global interannual variability during the past 40-years. In the pentad since 2006, Northern Hemisphere and global tropical cyclone ACE has decreased dramatically to the lowest levels since the late 1970s. Additionally, the global frequency of tropical cyclones has reached a historical low. Here evidence is presented demonstrating that considerable variability in tropical cyclone ACE is associated with the...
Show moreTropical cyclone accumulated cyclone energy (ACE) has exhibited strikingly large global interannual variability during the past 40-years. In the pentad since 2006, Northern Hemisphere and global tropical cyclone ACE has decreased dramatically to the lowest levels since the late 1970s. Additionally, the global frequency of tropical cyclones has reached a historical low. Here evidence is presented demonstrating that considerable variability in tropical cyclone ACE is associated with the evolution of the character of observed large-scale climate mechanisms including the El Niño Southern Oscillation and Pacific Decadal Oscillation. In contrast to record quiet North Pacific tropical cyclone activity in 2010, the North Atlantic basin remained very active by contributing almost one-third of the overall calendar year global ACE.
Show less
Date Issued: 2011
Identifier: FSU_migr_coaps_pubs-0039, 10.1029/2011GL047711
Format: Citation

Title: Quantifying variance due to temporal and spatial difference between ship and satellite winds.
Creator: May, J., Bourassa, Mark
Abstract/Description: Ocean vector winds measured by SeaWinds can be validated with comparison in situ data that are within a certain time and space range to the satellite overpass. The total amount of random observational error is composed of two primary components, which are quantified in this study: the uncertainty associated with the data sets and the uncertainty associated with the temporal and/or spatial difference between two observations. The variance associated with a temporal difference, which can be...
Show moreOcean vector winds measured by SeaWinds can be validated with comparison in situ data that are within a certain time and space range to the satellite overpass. The total amount of random observational error is composed of two primary components, which are quantified in this study: the uncertainty associated with the data sets and the uncertainty associated with the temporal and/or spatial difference between two observations. The variance associated with a temporal difference, which can be translated into a spatial difference using Taylor's hypothesis, between two observations is initially examined in an idealized case that includes only Shipboard Automated Meteorological and Oceanographic System (SAMOS) 1 min data. The results show that the amount of variance in wind speed and direction increases as the time difference increases, while the amount of variance in wind speed increases and direction decreases with larger wind speeds. Collocated SeaWinds and SAMOS observations are used to determine the total amount of variance associated with a temporal (equivalent) difference from 0 to 60 min. For combined differences less than 25 min (equivalent) and the selected wind speed bins, the variance associated with the temporal and spatial difference is dominated by small changes in the wind speed distribution, and the sum of the observational errors is approximately 1.0 m2 s-12 (12 deg2) and 1.5 m2 s-2 (10 deg2) for wind speeds between 4 and 7 m s-1 and 7-12 m s-1. For larger combined differences, the observational error variance is no longer the dominant term; therefore, the total variance is seen to gradually increase with increasing time differences.
Show less
Date Issued: 2011
Identifier: FSU_migr_coaps_pubs-0024, 10.1029/2010JC006931
Format: Citation

Title: Generation of an empirical soil moisture initialization and its potential impact on subseasonal forecasting skill of continental precipitation and air temperature.
Creator: Boisserie, Marie
Abstract/Description: The effect of the PAR technique on the model soil moisture estimates is evaluated using the Global Soil Wetness Project Phase 2 (GSWP-2) multimodel analysis product (used as a proxy for global soil moisture observations) and actual in-situ observations from the state of Illinois. The results show that overall the PAR technique is effective; across most of the globe, the seasonal and anomaly variability of the model soil moisture estimates well reproduce the values of GSWP-2 in the top 1.5 m...
Show moreThe effect of the PAR technique on the model soil moisture estimates is evaluated using the Global Soil Wetness Project Phase 2 (GSWP-2) multimodel analysis product (used as a proxy for global soil moisture observations) and actual in-situ observations from the state of Illinois. The results show that overall the PAR technique is effective; across most of the globe, the seasonal and anomaly variability of the model soil moisture estimates well reproduce the values of GSWP-2 in the top 1.5 m soil layer; by comparing to in-situ observations in Illinois, we find that the seasonal and anomaly soil moisture variability is also well represented deep into the soil. Therefore, in this study, we produce a new global soil moisture analysis dataset that can be used for many land surface studies (crop modeling, water resource management, soil erosion, etc.). Then, the contribution of the resulting soil moisture analysis (used as initial conditions) on air temperature and precipitation forecasts are investigated. For this, we follow the experimental set up of a model intercomparison study over the time period 1986-1995, the Global Land-Atmosphere Coupling Experiment second phase (GLACE-2), in which the FSU/COAPS climate model has participated. The results of the summertime air temperature forecasts show a significant increase in skill across most of the U.S. at short-term to subseasonal time scales. No increase in summertime precipitation forecasting skill is found at short-term to subseasonal time scales between 1986 and 1995, except for the anomalous drought year of 1988. We also analyze the forecasts of two extreme hydrological events, the 1988 U.S. Drought and the 1993 U.S. flood. In general, the comparison of these two extreme hydrological event forecasts shows greater improvement for the summertime of 1988 than that of 1993, suggesting that soil moisture contributes more to the development of a drought than a flood. This result is consistent with Dirmeyer and Brubaker [1999] and Weaver et al. [2009]. By analyzing the evaporative sources of these two extreme events using the back-trajectory methodology of Dirmeyer and Brubaker [1999], we find similar results as this latter paper; the soil moisture-precipitation feedback mechanism seems to play a greater role during the drought year of 1988 than the flood year of 1993. Finally, the accuracy of this soil moisture initialization depends upon the quality of the precipitation dataset that is assimilated. Because of the lack of observed precipitation at a high temporal resolution (3-hourly) for the study period (1986-1995), a reanalysis product is used for precipitation assimilation in this study. It is important to keep in mind that precipitation data in reanalysis sometimes differ significantly from observations since precipitation is often not assimilated into the reanalysis model. In order to investigate that aspect, a similar analysis to that we performed in this study could be done using the 3-hourly Tropical Rainfall Measuring Mission (TRMM) dataset available for a the time period 1998-present. Then, since the TRMM dataset is a fully observational dataset, we expect the soil moisture initialization to be improved over that obtained in this study, which, in turn, may further increase the forecast skill.
Show less
Date Issued: 2010
Identifier: FSU_migr_coaps_pubs-0002, fsu:209864
Format: Citation

Department of Earth, Ocean and Atmospheric Science (10)	+ -
Florida Climate Institute (3)	+ -
Department of Geography (1)	+ -

Atmospheric sciences (21)	+ -
Meteorology (21)	+ -
Oceanography (21)	+ -
Climate Change/statistics & numerical data (1)	+ -
Climate change mitigation (1)	+ -

Florida (1)	+ -
Forecasting (1)	+ -
Humans (1)	+ -
Models, Theoretical (1)	+ -
Public Health/trends (1)	+ -
Soil moisture (1)	+ -
United States (1)	+ -

text (50)	+ -
journal article (14)	+ -

Misra, Vasubandhu (11)	+ -
Wallcraft, Alan J. (6)	+ -
Arbic, Brian K. (5)	+ -
Bourassa, Mark (5)	+ -
Buijsman, Maarten C. (5)	+ -

Search In

Sort Results By:

Narrow results by:

Collection

Topical Subject

Genre

Type of Resource

Language

Creator

Found In

Owner