[Abstract submitted by author contains mathematical formula and special characters not supported in ASCII format. See PDF file for abstract.] / A Dissertation submitted to the Department of Meteorology in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Spring Semester, 2003. / April 3, 2003. / Solar Penetration, Ocean Circulation, Ocean Turbidity / Includes bibliographical references. / James J. O'Brien, Professor Directing Dissertation; Harley E. Hurlburt, Professor Co-Directing Dissertation; James B. Elsner, Outside Committee Member; Kwang-Yul Kim, Committee Member; Paul H. Ruscher, Committee Member; Xiaolei Zou, Committee Member.

Under the auspices of a nationwide effort led by NOAA, known as the Coastal Storms Initiative (CSI), the new Weather Research and Forecast (WRF) mesoscale model has been installed at the Jacksonville, FL (JAX) National Weather Service (NWS) Weather Forecast Office (WFO). The purpose of the CSI project is to lessen the impacts of storms on coastal communities. This research focuses on the local modeling component to determine the added skill of implementing the WRF model for improved forecasts of precipitation, coastal winds, and visibility. This marks first the time that this model has been applied operationally in an NWS WFO. A detailed evaluation is performed to determine whether the WRF model can serve as the local modeling component in the WFO in a manner similar to how the workstation Eta has in other WFOs. As decided by the NOAA entities involved, two simulations of the WRF model are run, one that is initialized using NOAA's Local Analysis and Prediction System (LAPS) and the other is initialized from NCEP's Eta 218 forecast grids. Thus, this project also seeks to address whether the use of a data assimilation component can improve local model forecasts. Both simulations are initialized at 06 UTC which allows for a direct comparison to the 12 km Eta model. The forecasts of the WRF version 1.3 and Eta model output are statistically evaluated for both the summer and fall seasons of 2003. Systematic errors of precipitation entities are studied with use of a modified Ebert & McBride precipitation verification technique based on morphology. The Contour Error Mapping method is applied to compare the skill of the WRF model to the Eta for the detection, transition timing, and propagation of sea breeze fronts for the entire model domain. This phenomelogical evaluation is performed for 58 days during the initial test period of the WRF model from the 2003 warm season. In addition, the performance of the WRF-LAPS is examined for tropical storm Henri. The WRF-LAPS outperforms the 12 km Eta model for sea breeze detection by a considerable margin. In addition, the ability of the WRF model to correctly forecast sea breeze, frontal, and pop-up convective rain entities through twenty-four hours helps to aide the JAX forecasters in issuing more accurate short term precipitation forecasts. The WRF-LAPS has superior visibility forecasts compared to the RUC2 and improved wind forecasts over both the Eta and WRF-Eta models. However, a strong warm temperature bias near the top of the boundary layer is routinely forecast, which results in an atmosphere forecast too stable and an aggressive cold bias near the surface. This bias disrupts the modeled sea breeze from experiencing accurate propagation and results in sea breeze convection with significant displacement errors. In July of 2004 the WRF version 2.0 was installed at the JAX WFO with the intention of correcting the afternoon temperature bias problem. Initial evaluations of the short term forecast reveals that the WRF-LAPS version 2.0 results in a drastic improvement for temperature forecasts and improves the performance for precipitation and sea breeze propagation. The encouraging forecast capability for important mesoscale features suggest that the WRF model could serve as a powerful tool for operational coastal forecasting. / A Thesis submitted to the Department of Meteorology in partial fulfillment of the requirements for the degree of Masters of Science. / Fall Semester, 2004. / October 21, 2004. / Operational Modeling, Mesoscale Modeling, Forecast Verification / Includes bibliographical references. / Paul Ruscher, Professor Directing Thesis; Mark Bourassa, Committee Member; Robert Hart, Committee Member.

In this study, two kinds of methodology are proposed for incorporating total column zone data from the Total Ozone Mapping Spectrometer (TOMS) into initial conditions of a mesoscale prediction model. The first methodology is based on the strong linear correlation between vertical mean potential vorticity (MPV) and TOMS ozone (O3). The second methodology assimilates the TOMS ozone observations directly by adding the ozone transport equation into the MM5 model and its adjoint. The three-dimensional ozone initial condition for the transport equation is estimated from the observed ozone. The proposed first approach of ozone assimilation is applied to two case studies. The first case is the notable Washington D. C. snow storm (to be called DCSTORM) that occurred between 24 - 25 January 2000 along the East Coast of the United States. The second case is an Atlantic Ocean winter storm that was observed between 14-16 February 1997 (to be called AOSTORM). It is found that adjustments in model initial conditions assimilating TOMS ozone-only data are confined to the upper levels and produced almost no impact to the prediction of the storm development. However, when TOMS ozone data are used together with radiosonde observations, a more rapid deepening of the sea level pressure of the simulated storm is observed than with radiosonde-only observations. The predicted motion of the DCSTORM is also altered, with a track closer to the coast. On the contrary, assimilation of only TOMS ozone data produces non-negligible adjustment of wind and temperature fields at all levels in the AOSTORM case. When compared with dropsonde observations, TOMS ozone data improves model forecasts of both temperature and moisture fields. Adjoint sensitivity studies indicate that the significant impact of TOMS ozone on cyclone prediction is expected if large TOMS ozone anomalies appear in a region where model error is grow. / A Dissertation submitted to the Department of Meteorology in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Spring Semester, 2004. / March 23, 2004. / Winter Storm, TOMS Ozone, 4D-Var / Includes bibliographical references. / Xiaolei Zou, Professor Directing Dissertation; Ionel M. Navon, Outside Committee Member; Albert I. Barcilon, Committee Member; T. N. Krishnamurti, Committee Member; James J. O'Brien, Committee Member.

The spatial and temporal variability of the surface turbulent heat fluxes over the North Atlantic is examined using the new objectively produced FSU3 monthly mean 1°x1° gridded wind and surface flux product for 1978-2003. The FSU3 product is constructed from in situ ship and buoy observations via a variational technique. A cost function based on weighted constraints is minimized in the process of determining the surface fluxes. The analysis focuses on a low frequency (basin wide) mode of variability where the latent and sensible heat flux anomalies transition from mainly positive to negative values around 1998. It is hypothesized that the longer time scale variability is linked to changes in the large scale circulation patterns possibly associated with the Atlantic Multidecadal Oscillation (AMO; Schlesinger and Ramankutty 1994, Kerr 2000). The changes in the surface heat fluxes are forced by fluctuations in the mean wind speed. Zonal averages show a clear dissimilarity between the turbulent heat fluxes and wind speed for 1982-1997 and 1998-2003 over the region extending from the equator to roughly 40°N. Larger values are associated with the earlier time period, coinciding with a cool phase of the AMO. The separation between the two time periods is much less evident for the humidity and air/sea temperature differences. The largest differences in the latent heat fluxes, between the two time periods, occur over the tropical, Gulf Stream, and higher latitude regions of the North Atlantic, with magnitudes exceeding 15 Wm-2. The largest sensible heat flux differences are limited to areas along the New England coast and poleward of 40°N. / A Thesis submitted to the Department of Meteorology in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester, 2006. / March 29, 2006. / Decadal, North Atlantic, Sensible Heat Flux, Latent Heat Flux, Variability / Includes bibliographical references. / Mark A. Bourassa, Professor Directing Thesis; Kwang-Yul Kim, Committee Member; Ming Cai, Committee Member.

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 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. / A Dissertation submitted to the Department of Meteorology in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Spring Semester, 2010. / January 26, 2010. / Soil Moisture, Land-Atmosphere Interactions, Climate Forecast / Includes bibliographical references. / James O’Brien, Professor Directing Dissertation; Eric Chassignet, University Representative; Steven Cocke, Committee Member; Paul Ruscher, Committee Member; Xiaolei Zou, Committee Member.

While coastal areas along the United States Atlantic and Gulf Coasts have become increasingly accustomed to dealing with landfalling hurricanes and tropical storms, populations further inland can often be surprised by powerful storms that retain their intensity more than forecast. Hurricane Ike in 2008 is one of the more recent examples of such surprise, as it generated gusts to hurricane force well into the Ohio Valley after interaction with an unusually strong baroclinic trough. Considerable research has studied the development and intensification of hurricanes; however, there is a comparative lack of research on the topic of the variety in their decay over land. Statistical studies of the decay problem date back to the 1950s, and many of the tropical cyclone modeling studies of the 1960s and 1970s refined the debate as to the primary cause of overland decay (or intensification) of tropical cyclones. Several seminal works have created a partial climatology of the overland decay of cyclones in the Atlantic basin; however, few have been comprehensive in nature and none have examined in detail the characteristics associated with anomalous decay rates. This study presents that comprehensive climatology based on all available reliable tropical cyclone data in the Best Track Data Set. The mean decay rate of US landfalling tropical cyclones between 1950 and 2006 (in terms of pressure and wind decay), its variability in time and space, and its overall distribution, are determined empirically once the storm makes landfall along the coastline. The second focus of this study is to analyze the particular characteristics of a storm and the synoptic setup that allow the TC to maintain strength (or weaken unusually quickly) while traversing a landmass. The size, structure, and strength at landfall of storms that exhibit an abnormally slow or fast decay rate will be analyzed and physically interpreted to determine what enables a TC to retain or lose an unusual fraction of its strength. Composite maps of the synoptic setup associated with slowly and quickly decaying storms, normalized to the point of landfall, will lend insight into how the environment contributes to their anomalous decay. / A Thesis submitted to the Department of Meteorology in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester 2009. / December 4, 2008. / Intensity Change, Decay, Climatology, Meteorology, Tropical Cyclones / Includes bibliographical references. / Robert Hart, Professor Directing Thesis; Henry Fuelberg, Committee Member; Paul Reasor, Committee Member.

Curvature vorticity and shear vorticity are examined in an attempt to elucidate the physical mechanisms behind tropical cyclone (TC) intensity change. A particular emphasis is placed on the role of the shear to curvature vorticity conversion term throughout this study. Curvature vorticity and shear vorticity budgets are calculated from the equations given by Bell and Keyser (2003) using data from a case study of TC Ivan (2004) simulated using the Pennsylvania State University-National Center for Atmospheric Research (PSU-NCAR) fifth generation non-hydrostatic Mesoscale Model (MM5). The first portion of this analysis focuses on describing the spatial and temporal evolution of each of the relevant terms. Given the use of an Earth relative reference frame, the terms studied in this analysis are limited to the vertical advection term, vorticity conversion term, stretching term, and tilting term. Storm centered azimuthal spectral analyses are relied upon to elucidate the primary scales at which each term is organizing at. Following this, layer averages of the areal-average of the magnitude of each term and the areal-average of each term within a 0.5° radius of the TC center are used to perform an intercomparison between tendency terms as well as for the purpose of relating each to changes in minimum sea level pressure. Although correlation coefficients are as high as 0.52, the computations are unable to directly link one single term in either the curvature vorticity tendency or shear vorticity tendency equation to the intensity change of the TC. To further examine the role of shear to curvature vorticity conversions in intensity change, hindcasts of selected storms from the 2004-2006 Atlantic hurricane season simulated using the Weather Research and Forecast system for hurricane prediction (HWRF) are examined to determine if a correlation exists between the shear to curvature vorticity conversion term and intensity change. Specifically, this portion of the study focuses on the initial hour of the hindcast given the interest in using calculated values of the vorticity conversion term as an operational product for predicting intensity change. Areal-averages and spectral analysis are used to compute a single value used for correlation with intensity change. Prior to performing this analysis, an evaluation of the physical consistency of the initial vortex used in the HWRF hindcasts with best track data (Jarvinen et al., 1984) is performed using wind-pressure relationships. While the wind-pressure relationship for the initial vortex is in reasonable agreement with best track observations for TCs with wind speeds below 50 m/s, a low bias in the minimum sea level pressure of the vortex is noted for maximum wind speeds above this threshold. Additionally, the HWRF initial vortex undergoes gradient adjustment during the first 6 hours of the forecast that becomes increasingly larger with increasing wind speeds. The results of the correlation show a more robust relationship between vorticity conversions and current intensity (R²<0.77) rather than for intensity change (R²<0.1). Although reasons for why the diagnostic relation exists are unclear, plausible explanations include the initialization scheme, spatial resolution of the model, and the parameterizations used. / A Thesis submitted to the Department of Meteorology in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester, 2009. / January 8, 2009. / Curvature Vorticity, Shear Vorticity, Shear Vorticity to Curvature Vorticity Conversion, Tropical Cyclone Intensity Prediction / Includes bibliographical references. / T. N. Krishnamurti, Professor Directing Thesis; Robert Hart, Committee Member; Paul Ruscher, Committee Member.

Advanced Technology Microwave Sounder (ATMS) has been flying on the Suomi National Polar-orbiting Partnership (NPP) satellite since October 28, 2011. A striping phenomenon contained in the global distribution of O (observations) minus B (model simulations) difference was detected in different ATMS channels. In this dissertation, optimal filters are designed for smoothing out the striping noise in warm counts, cold counts, warm load temperatures and scene counts. The optimal filters are developed based on the striping noise free results obtained by a combined method of the principal component analysis (PCA) and the Ensemble Empirical Mode Decomposition (EEMD). Using the two-point algorithm, antenna temperatures are then calculated with warm counts, cold counts, warm load temperatures and scene counts before and after applying the optimal filters. The patterns and magnitudes of the striping noise removed are very close to that from the PCA/EEMD method. It is further demonstrated that the striping noise is present in the scene counts and must be smoothed out in order to eliminate the striping noise in antenna temperatures. It is also shown that the optimal filters are superior to the conventional boxcar filters in terms of being able to effectively remove the striping noise in the high frequency range but not to alter the lower frequency weather signals. A set of 22 optimal filters on brightness temperature is also designed to remove the striping noise in different channels. Impacts of striping noise mitigation on small-scale weather features are investigated by comparing ATMS cloud liquid water path (LWP) retrieved before and after striping noise mitigation. It is shown that the optimal filters do not affect small-scale cloud features while smoothing out striping noise in brightness temperatures. It is also shown that the striping noise is present in the LWP retrievals if the striping noise in brightness temperatures of ATMS channels 1 and 2 is not removed. The amplitude of the striping noise in LWP is found to be linearly related to the magnitude of striping noise in ATMS brightness temperature observations. Striping noise is a general problem for microwave sensors, and is also identified within observations of a recent FY-3C MWTS. Striping noise within MWTS observation is with a magnitude of 1K, which is much larger than in ATMS. A transfer function is employed to explain the root cause of the striping noise. This transfer function is controlled by instrument parameters such as scan cycle, calibration integration time and scene integration time. Instrument noise is simulated by a white noise series with and without adding flicker noise. Power spectral analysis of this instrument noise is then forced by transfer function to produce the power spectral density of output noise. It is shown that flicker signal is the source of striping noise, and transfer function can modify the striping noise in terms of magnitude and peak frequency. / A Dissertation submitted to the Department of Earth, Ocean, and Atmospheric Science in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Summer Semester 2015. / June 4, 2015. / Includes bibliographical references. / Ming Cai, Professor Directing Dissertation; Xin Yuan, University Representative; Guosheng Liu, Committee Member; Peter Ray, Committee Member; Jeffery Chagnon, Committee Member.

Lightning inhibits normal operating conditions at the Kennedy Space Center (KSC) and other locations, leading to inconvenience and detrimental economic impacts. Lightning cessation guidance must safely protect lives and infrastructure. This research focuses on "nonisolated" lightning cases which we defined as one cell whose flashes had ceased while embedded in weak composite reflectivity (Z ≥ 15 dBZ) with another cell still producing flashes. The dataset consisted of 50 warm season (May-September) nonisolated storms near KSC during 2013. The research utilized the National Lightning Detection Network (NLDN), the second generation Lightning Detection and Ranging (LDAR-II), and dual polarimetric radar data. These data were merged and analyzed using the Warning Decision Support System-Integrated Information (WDSS-II) at 1 min intervals. The parameters, such as horizontal reflectivity (ZH), that decreased greatest during the cessation period were ZH > 40 dBZ at -5°C, ZH > 35 dBZ at -10°C, graupel presence at -10°C, and graupel presence at -15°C. We tested 60 cessation schemes utilizing a wait time approach. Our safest scheme required that the distance from our decaying storm's 30 dBZ core to the closest signature of graupel associated with the active storm (30G) be greater than 10 nm (~19 km) and the horizontal reflectivity be less than 40 dBZ at -5°C for 10 min. In the independent (dependent dataset), this scheme produced one (zero) false alarm. More research is needed to analyze nonisolated cessation, since no algorithm produced perfect skill when applied to the independent dataset. / A Thesis submitted to the Department of Earth, Ocean, and Atmospheric Sciences in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester 2016. / March 1, 2016. / Cessation, Lightning / Includes bibliographical references. / Henry E. Fuelberg, Professor Directing Thesis; Ming Cai, Committee Member; Jeffrey Chagnon, Committee Member.

This study explores extreme surface temperature events in Southern Hemisphere winter (June – August) from 1979 to 2011 and their relation with meridional mass circulation by using daily ERA-interim Re-Analysis data from European Center for Medium-Range Weather Forecasts (ECMWF). Meridional mass circulation indices are developed to quantitatively represent the warm air mass being transported into the polar region in the upper atmosphere and the cold air mass being transported out of the polar region in the lower atmosphere. Our results show that weaker poleward warm air mass transport aloft is associated with weaker cold air transport toward equator in the lower troposphere, resulting in cold air being confined in the polar regions. Similarly, stronger poleward warm air mass transport in the upper atmosphere is related to stronger cold air transport out of the polar regions, causing enormous cold air outbreaks in the mid-latitude regions. We find that regions to the south of 45S exhibit a robust relationship between surface air temperature anomalies and meridional mass circulation. Weaker circulation is associated with abnormally cold in Antarctica and abnormally warm in regions from 45S to 60S. Conversely, stronger circulation is related to anomalously warm in Antarctica and anomalously cold in the surrounding continental shelf, particularly over Weddell-Scotia Sea and north Ross Sea where are the two preferred routes for cold air coming out of Antarctica. On the other hand, temperature anomalies over the regions north of 45S are not sensitive to the meridional circulation variability. The fact that surface air temperature anomalies over the Southern Ocean rarely exceed 4C suggests that cold air coming out of Antarctic has limited impacts on the Southern Ocean due to its large thermal inertia. In summary, the meridional mass circulation indices provide a robust diagnostics for extreme cold events in 45S - 90S domain very well, but may not be adequate to describe all cold events over the vast mid-latitude regions in the Southern Hemisphere. / A Thesis submitted to the Department of Earth, Ocean and Atmospheric Science in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester 2016. / April 13, 2016. / cold air outbreak, extreme temperature events, meridional mass circulation, southern hemisphere / Includes bibliographical references. / Ming Cai, Professor Directing Thesis; Jeffrey M. Chagnon, Committee Member; Guosheng Liu, Committee Member.