Over the past few decades, several single radar methods have been developed to probe the kinematic structure of storms. All these methods trade angular-resolution to retrieve the wind-field. To date, the spaced-antenna method has been employed for profiling the ionosphere and the precipitation free lower atmosphere. This work focuses on applying the spaced-antenna method on an X-band active phased-array radar for high resolution horizontal wind-field retrieval from precipitation echoes. The ability to segment the array face into multiple displaced apertures allows for flexible spaced-antenna implementations. The methodology employed herein comprises of Monte-Carlo simulations to optimize the spaced-antenna system design and analysis of real data collected with the designed phased-array system. The contribution that underpins this dissertation is the demonstration of qualitative agreement between spaced-antenna and Doppler beam swinging retrievals based on real data. First, simulations of backscattered electric fields at the antenna array elements are validated using theoretical expressions. Based on the simulations, the degrees of freedom in the spaced-antenna system design are optimized for retrieval of mean baseline wind. We show that the designed X-band spaced-antenna system has lower retrieval uncertainty than the existing S-band spaced-antenna implementation on the NWRT. This is because of the flexibility to synthesize small overlapping apertures and the ability to obtain statistically independent samples at a faster rate at X-band. We then demonstrate a technique to make relative phase-center displacement measurements based on simulations and real data from the phased-array spaced-antenna system. This simple method uses statistics of precipitation echoes and apriori beamwidth measurements to make field repeatable phase-center displacement measurements. Finally, we test the hypothesis that wind-field curvature effects are common to both the spaced-antenna and Doppler beam swinging methods. Based on a close-range winter storm data set, we find that the spaced-antenna and fine-resolution Doppler beam swinging retrievals are in qualitative agreement. The correlation between the spaced-antenna and fine-resolution Doppler beam swinging retrievals was 0.57. The lowered correlation coefficient was, in part, due to the high standard deviation of the DBS retrievals. At high wind-speeds, the spaced-antenna retrievals significantly departed from variational retrievals of mean baseline wind.

Ocean wind vectors from the SeaWinds scatterometer on QuikSCAT and GOES imagery are used to develop an objective technique that can detect and monitor tropical disturbances associated with the early stages of tropical cyclogenesis in the Atlantic basin. The technique is based on identification of surface vorticity and wind speed signatures that exceed certain threshold magnitudes, with vorticity averaged over an appropriate spatial scale. The threshold values applied herein are determined from the precursors of 15 tropical cyclones during the 1999-2004 Atlantic hurricane seasons using research-quality QuikSCAT data. Tropical disturbances are found for these cases within a range of 19 hours to 101 hours before classification as tropical cyclones by the National Hurricane Center (NHC). The 15 cases are further subdivided based upon their origination source (i.e., easterly wave, upper-level cut-off low, stagnant frontal zone, etc). Primary focus centers on the cases associated with tropical waves, since these waves account for approximately 63% of all Atlantic tropical cyclones. The detection technique illustrates the ability to track these tropical disturbances from near the coast of Africa. Analysis of the pre-tropical cyclone (TC) tracks for these cases depict stages, related to wind speed and precipitation, in the evolution of an easterly wave to tropical cyclone. / A Thesis submitted to the Department of Meteorology in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester, 2006. / November 22, 2005. / Quikscat, Seawinds, Tropical Disturbance, Tropical Cyclogenesis, Vorticity / Includes bibliographical references. / James J. O’Brien, Professor Directing Thesis; Mark A. Bourassa, Committee Member; Paul D. Reasor, Committee Member.

The need for a surface based, dense meteorological observation network in Florida has long been recognized. In 2002, scientists across the state of Florida joined together with the National Science Foundation, the REALM Project, the Florida State University, and other agencies to create the Miami-Dade Mesonet. This research is a study of the instruments used in the Miami-Dade Mesonet (the Davis Vantage Pro Weather Instruments) and of the data collected by the mesonet. The goal is to prove that though the Davis Weather Instruments are inexpensive, and the placement of the instruments in the mesonet do not meet all the operational standards and procedures for surface observing, that the mesonet can still produce accurate and practical observations. This research will present an overall assessment of the accuracy and quality of the data collected. First, an internal examination of three Davis weather instruments was conducted on the roof of the James J. Love Math-Meteorology building on the FSU campus, in order to evaluate the integrity of the equipment in a controlled setting with varying parameters. Next, quality assurance procedures were run on the actual data from the Miami-Dade Mesonet to determine how well the mesonet compares with Automatic Surface Observing Systems (ASOS). Then, four case studies were conducted to examine the ability of the instruments to detect specific types of weather events, including a tornado outbreak, a record high temperature in mid-winter, a heavy rainfall event, and a sea breeze passage case. Each study evaluated a different aspect of the mesonet stations, leading to positive results proving that the systems provide operationally significant observations. The REALM Project was extended in the summer of 2005 through the Florida Panhandle and parts of central Florida, which will greatly increase observational coverage in data sparse regions in rural areas, especially in northwest Florida. / A Thesis submitted to the Department of Meteorology in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester, 2006. / November 1, 2005. / Mesonet, Miami-Dade Mesonet, Florida Mesonet, Fsu Meteorology, Rooftop Weather Stations, Rooftop Weather Systems, Davis Instruments, Mesoscale Meteorology, Mesoscale Network / Includes bibliographical references. / Paul Ruscher, Professor Directing Thesis; Carol Anne Clayson, Committee Member; Robert Hart, Committee Member; Andrew I. Watson, Outside Committee Member.

In this study, the Petterssen-Sutcliffe development equation is used to examine cyclogenesis. In the past, several other methods have been used to study cyclogenesis and calculate vertical motion, such as the kinematic and adiabatic methods, quasi-geostrophic theory as well as the approaches derived from them. However, there is little documentation on the application of the historical Petterssen-Sutcliffe method, and hence the motivation for this study. The forcing terms of the Petterssen-Sutcliffe development equation are calculated using GEMPAK software. These forcing terms include vorticity advection, temperature advection, stability, and diabatic heating. Two mid-latitude storms and two tropical systems were analyzed to see if this method could recognize cyclogenesis in both baroclinic and barotropic environments. The first mid-latitude storm occurred in late January 2000. It formed off the coast of the Carolinas and traveled up the East Coast over the Atlantic Ocean. The second storm spent its life cycle over land in the Mid-Atlantic and New England regions during March 1999. Both tropical systems originated in the Gulf of Mexico: Hurricane Earl (1998) and Hurricane Gordon (2000). This method of analysis was shown to have general success in identifying cyclogenesis of mid-latitude cyclones and somewhat limited success with tropical storms. It is hoped that this method will benefit both educational and operational environments where students and forecasters can use this additional analysis to supplement their understanding of the atmosphere. / A Thesis submitted to the Department of Meteorology in partial fulfillment of the requirements for the degree of Master of Science. / Fall Semester, 2004. / June 16, 2004. / Surface Tendency / Includes bibliographical references. / Paul Ruscher, Professor Directing Thesis; Henry Fuelberg, Committee Member; T. N. Krishnamurti, Committee Member.

Atmospheric conditions during the dry season of the South American monsoon are instrumental in the initiation of convection during the wet season and are strongly correlated to SSTs within the Atlantic Warm Pool. Subsequently, accurate seasonal prediction of temperature and rainfall during the dry season has the potential to improve our understanding of and the predictability of these variables during future seasons. In this study, we review the fidelity of South American dry season (June-July-August) reforecasts from one global climate model (GCM), and one downscaled regional climate model (RCM). Additionally, we evaluate a second integration of the RCM that uses a bias correction method called anomaly nesting, which is designed to remove the bias of the GCM before the downscaling process is performed. The models are integrated for seven dry seasons (2001–2007), and each season consists of six ensemble members. For this study, we focus on two primary regions: the Amazon River Basin (ARB) and the subtropical region (ST). There are three objectives of this research. The first is to locate regions of model bias for two-meter air temperature and for precipitation within the ARB and the ST using NCEP Climate Forecast System Reanalysis (CFSR) as a comparison dataset. The second is to evaluate the predictability of above normal, normal, and below normal occurrences of the two variables using potential predictability ratios and calculations of the area under the relative operative characteristic (ROC) curve (AUC). Through this analysis we should be able to determine whether downscaling or anomaly nesting improve upon the skill of the GCM. Lastly we wish to evaluate how the three models depict land-atmosphere interactions during the dry season and compare their results with results from CFSR. The models produced the largest biases of both variables over elevated terrain and within the Intertropical Convergence Zone (ITCZ). However, neither of these locations significantly impacts the ARB or the ST. Signal-to-noise ratios show that the ARB exhibits more potential predictability than the ST and that temperature exhibits more potential predictability than precipitation. AUCs confirm that temperature is more skillfully predicted than precipitation and that the models exhibit more skill in the ARB than in the ST. AUCs show that the downscaled and the downscaled with anomaly nesting integrations display more skill than the GCM integration, particularly in the ARB. Lastly, we find conflicting results between the models and CFSR regarding how the land and the atmosphere interact during the dry season. However, a full moisture budget analysis is needed to completely resolve land-atmosphere feedbacks and that is beyond the scope of this study. / A Thesis submitted to the Department of Earth Ocean and Atmospheric Sciences in partial fulfillment of the requirements for the degree of Masters of Science. / Spring Semester, 2011. / March 17, 2011. / RSM, CFS, Anomaly Nesting, Climate Model / Includes bibliographical references. / Vasubandhu Misra, Professor Directing Thesis; Henry Fuelberg, Committee Member; Philip Sura, Committee Member.

Anthropogenic pollution impacts many of the Earth's natural processes. Therefore, understanding the mechanisms that transport pollutants from the surface to the free atmosphere is important for understanding the chemical composition of the atmosphere. This study quantifies the vertical transport of lower tropospheric carbon monoxide (CO) by deep convection associated with mesoscale convective systems. Three squall line simulations (C1-C3) based on different environmental wind shear profiles are made using the 2-D Goddard Cumulus Ensemble, each providing post-convection CO profiles. Then, the Tropospheric Emission Spectrometer (TES) instrument's ability to resolve the convectively modified CO distribution is analyzed during one of the cases (C3) using a 'clear-sky' retrieval scheme. Results show that environmental wind shear not only impacts the structure of squall lines, but also their transport characteristics. The squall line simulation with the strongest low-level vertical wind shear is found to transport the greatest net mass of CO, with an amount of 13 421 metric tons in the low levels and 43 916 metric tons in the middle levels of the atmosphere. However, the storm with the weakest low-level vertical wind shear and weakest environmental winds aloft has a greater mass of CO transported by the updraft and the downdraft than either of the two other storms. The study finds that stronger environmental winds in the upper troposphere play an important role in the propagation speed of the squall line, which in turn impacts the horizontal distribution of convectively lofted CO. Results also show that TES has sufficient sensitivity to resolve convectively lofted CO, as long as the retrieval scene is cloud-free. TES swaths that are located downwind of squall lines are found to have the greatest chance of sensing convective transport because the impact of clouds on retrieval quality becomes less of an issue further from the squall line. / A Thesis submitted to the Department of Meteorology in partial fulfillment of the requirements for the degree of Master of Science. / Summer Semester, 2007. / July 5, 2007. / GCE, Cloud Venting, Meteorology, Squall Line, MCS, Mesoscale Convective System, Pollution Transport, Carbon Monoxide, CO, TES, Tropospheric Emission Spectrometer, Goddard Cumulus Ensemble / Includes bibliographical references. / Henry E. Fuelberg, Professor Directing Thesis; Guosheng Liu, Committee Member; Robert Hart, Committee Member.

The inter-annual variability of typhoon landfalls in China is investigated using historical and modern records. A north-to-south anti-correlation in yearly activity is confirmed from the historical records. When activity over Guangdong is high, it tends to be low over Fujian and vice versa. This spatial variation is identified in the modern record using a factor analysis model, which delineates the southern provinces of Guangdong, and Hainan from the northern provinces of Fujian, Taiwan, Zhejiang, Shanghai,Jiangsu, and Shandong. An index of annual activity representing the degree to which each year follows this pattern of activity is used to identify correlated climate variables. A useful model that includes sea level pressure differences between Mongolia and western China and SST over the midlatitude NW Pacific during the summer explains 27% of the inter-annual variability of the index. Physically, we suggest that a stronger than normal north to south pressure gradient increases the surface easterly wind flow over northern China, this coupled with lower SST over midlatitude NW Pacific, favors typhoons taking a more southerly track toward Hong Kong. / A Thesis submitted to the Department of Geography in partial fulfillment of the requirements for the degree of Master of Science. / Fall Semester, 2004. / October 20, 2004. / Southern China, Typhoon Landfall, Variablity Historical Data / Includes bibliographical references. / James B. Elsner, Professor Directing Thesis; Thomas Jagger, Committee Member; J. Anthony Stallins, Committee Member.

The goal of this investigation was to determine whether highly accurate sampling and dating methods could be employed to develop a high-resolution history of barrier evolution and sea-level change. The focus of the study was St. Vincent Island, an undeveloped barrier island beach ridge plain in the northeastern Gulf of Mexico. The island consists of more than 100 beach ridges organized into a dozen groups or sets based on their topographic expression and geographic pattern. These ridges represent sequential paleo-shoreline positions over the 4000+ year history of the island. Given the long-term tectonic stability of the northern Gulf of Mexico throughout the Quaternary, the island holds the potential for a unique high-resolution chronology of mid- to late-Holocene sea-level change. The sampling of the beach ridges by means of trenches, rather than just cores, allowed for the collection of basal deposits as well as visual confirmation of the origin and structure of the ridges. Ground penetrating radar (GPR) profiles confirmed the origin and structure of the ridges. Based on these techniques it is evident that the beach ridges on the island were built by swash processes rather than by storms. The direct dating of quartz grains collected from the base of several of the islands beach ridges via optically stimulated luminescence dating (OSL) provided an accurate measure of the depositional ages of the ridges. The ridges on St. Vincent Island have ages ranging from zero to 4,100 years, with the oldest ridges on the north side of the island and the youngest ridges on the southeast side of the island. These ages can be correlated with the most recent sea level curve produced for the northern Gulf of Mexico. These ages have also been used in conjunction with topographic maps, leveling or topographic profile surveys and LIDAR data, to calculate the rates of beach ridge plain progradation and beach ridge formation over time. Results show that during times of sea level fall, the progradation rates on St. Vincent Island were relatively fast while during times of sea level rise, rates were considerably slower. The result of this project is a better and more detailed understanding of the influence of sea-level change on barrier island development. / A Dissertation submitted to the Department of Geological Sciences in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Spring Semester, 2007. / April 2, 2007. / Sea Level, St. Vincent Island, Barrier Island Evolution, Beach Ridges, Gulf of Mexico, Sea Level, Holocene / Includes bibliographical references. / Joseph F. Donoghue, Professor Directing Dissertation; Philip N. Froelich, Outside Committee Member; Sherwood W. Wise, Committee Member; Sergio Fagherazzi, Committee Member; Stephen A. Kish, Committee Member; Alan W. Niedoroda, Committee Member.

The redox speciation of dissolved iron in open ocean seawater was evaluated during two Pacific Ocean research cruises. Using a sensitive flow injection method based on luminol chemiluminescence, vertical profiles of reduced iron concentration, Fe(II), were obtained at 134 stations. In this paper, sampling and analytical methods are discussed and values obtained for Fe(II) are compared to shipboard measurements of total dissolved iron. Concentration profiles are evaluated within the context of various proposed source mechanisms and experimental models of Fe(II) oxidation kinetics. Samples were collected from rosette-mounted GO-FLO bottles, enabling retrieval of uncontaminated samples from depths of 20 - 1000 m. The length of time required for rosette retrieval coupled with the potential for rapid oxidative loss of Fe(II) complicates the detection of photochemical production processes. Acidification of seawater samples retards oxidation until sample analyses can be completed, but for undetermined reasons it contributes both to the blank response, and to minor instabilities in system response over time that are depth-specific, effects which must be considered and corrected for. The analytical method typically yielded detection limits of 10-15 pM. Potential interferences include reduced vanadium species that contribute to the analytical response, and dissolved organic matter, which has been found to decrease response. The results from the two cruises suggest a relatively consistent pattern of Fe(II) occurrence and distribution in the Pacific Ocean. Surface water maxima are present in most profiles, with median concentrations of 25-30 pM, accounting for approximately 12% of the dissolved iron. Concentrations decline with depth to undetectable levels in the upper euphotic zone. Fe(II) was frequently detected in deepest samples, constituting a small fraction of the dissolved iron. The concentration profiles are suggestive of photochemical processes; however, no diel bias was observed and Fe(II) persisted in GO-FLOs well beyond the lifetime predicted by oxidation models. Fe(II) in deep samples was found in association with the local oxygen minimum, possibly due to the remineralization of sinking biogenic particles. In the northern Philippine Sea, between the Japanese coast and the Izu-Bonin volcanic arc system, Fe(II) concentrations were found to be atypically high, possibly due to dust and sediment-derived iron. / A Dissertation submitted to the Department of Oceanography in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Summer Semester, 2007. / March 16, 2007. / Iron Speciation, Seawater, Clivar / Includes bibliographical references. / William M. Landing, Professor Directing Dissertation; William C. Cooper, Outside Committee Member; William Burnett, Committee Member; Philip Froelich, Committee Member; Richard Iverson, Committee Member.

The National Aeronautics and Space Administration (NASA) conducted the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) mission during 2008 as a part of the International Polar Year (IPY). The purpose of ARCTAS was to study the factors responsible for changes in the Arctic's atmospheric composition and climate. A major emphasis was to investigate Arctic haze that is most pronounced during winter and early spring. This study focuses on the spring phase of ARCTAS (ARCTAS-A) that was based in Alaska during April 2008. Although anthropogenic emissions historically have been associated with Arctic haze, biomass burning dominated the ARCTAS-A period and has been the focus of many ARCTAS related studies. This study determines the common pathways for anthropogenic emissions during ARCTAS-A. Trajectories are released each day from three historically significant regions of anthropogenic emissions (Asia, North America, and Europe). These fifteen day forward trajectories are calculated using data from the Weather Research and Forecasting (WRF) model at 45 km horizontal resolution. The trajectories then are examined to determine: Origins of emissions that reach the Arctic (defined as 70oN), pathways of the emissions reaching the Arctic, Arctic entry locations, and altitudes at which the trajectories enter the Arctic. These results serve as regional "climatologies" for the ARCTAS-A period. Three cases during the ARCTAS-A period (one for each of the regions above) are examined using backward trajectories and chemical fingerprinting based on in situ data sampled by the NASA DC-8. The fingerprinting utilizes volatile organic compounds that represent pure anthropogenic tracers, Asian anthropogenic pollution, incomplete combustion, and natural gas emissions. We determine flight legs containing anthropogenic emissions and the pathways travelled by these emissions. Results show that the DC-8 sampled anthropogenic emissions from Asia, North America, and Europe during the spring phase of ARCTAS. The pathways travelled by these emissions agree with our derived "climatologies" and previous studies of Arctic transport. Meteorological analysis and trajectory calculations indicate that middle latitude cyclones and their associated warm conveyor belts play an important role in lofting the surface based emissions to their sampling altitude in all three cases. / 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. / Fall Semester, 2010. / September 30, 2010. / ARCTAS, Pollution, Anthropogenic, Emissions, Arctic, Arctic Haze, Transport, Trajectories / Includes bibliographical references. / Henry E. Fuelberg, Professor Directing Thesis; Guosheng Liu, Committee Member; Robert Hart, Committee Member.