This document presents an approach using the maximum likelihood formulation to estimate vector velocities in real-time by a network of Doppler radars. Relationships between the estimated vector velocity, the statistics of the measured signals, the characteristics of the observing geometry, and the hardware and signal processing parameters is derived. Metrics to gauge the quality of vector velocity retrievals are presented, and their utilization for network design and operation is provided. The thesis concludes with a software architecture for real-time implementation of the vector velocity estimation and its demonstration within the framework of the CASA IP1 four node radar network.

The effect that the Polar stratospheric clouds (PSCs) have on the destruction of ozone in the polar vortex is well known. The study of these clouds is therefore highly relevant and important. A tool that can be used to gather parameters needed to describe the PSC is a lidar (Light Detection and Ranging). The Swedish Institute of Space Physics (IRF) uses such a lidar to observe PSCs above Kiruna in northern Sweden. The lidar works by emitting polarised light and then collecting the scattered light. Knowing the time between when the light was emitted and the backscattered light was collected one can then determine at which altitude the scattering happened. The time and the backscattered light can then be used to derive the useful parameters needed to create a climatology of the PSCs. When creating a climatology, the different types of PSCs (type Ia, Ib and II) have to be classified. Each of the different types is classified by looking at the PSCs parallel and perpendicular backscatter ratio as well as the depolarisation ratio. The classification can then be used to understand the formation and composition of the cloud. To process the data gathered from the lidar a script in MATLAB is developed. The script is automatically going through the data and pinpointing the boundaries and interpolate the data, then using this to calculate the backscatter and depolarisation ratio. The script runs for all the available IRF observations between 2008 and 2018. The ratios and boundaries calculated from all the observations are then used to create a climatology. Comparing the climatology to the climatology by Blum et. al \cite{Psct} shows similar results. Future work should be done on the MATLAB program to inprove finding parameters from observation where the data includes more noise than the program can currently handle. This enables the retrieval of more trusty parameters and a more precise climatology.

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To evaluate the influence of dietary carbon on fish otoliths, juvenile red drum (Sciaenops ocellatus) were raised for 6 and 9 months in tanks with flow-through ambient seawater and fed diets differing by 2.12‰ (p < 0.001) in carbon isotope composition (del 13C). Muscle tissue from the two treatment groups also differed by 2.12‰ (p / A Thesis submitted to the Department of Oceanography in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester, 2004. / February 27, 2004. / Otoliths, Stable Carbon Isotope / Includes bibliographical references. / Jeffrey P. Chanton, Professor Directing Thesis; Christopher C. Koenig, Outside Committee Member; Nancy Marcus, Committee Member; Joel E. Kostka, Committee Member.

This series of studies evaluates the ability of global climate models (GCMs) to simulate the observed relationship between the upper limit of tropical cyclone (TC) intensity and sea surface temperature (SST). Previous studies addressed whether GCMs are capable of reproducing observed TC frequency and intensity distributions. This research builds upon these earlier studies by examining how well GCMs capture physically relevant relationships that are important for understanding the impacts of climate change on TC intensity. The research presented here aims to 1) quantify differences between the observed and simulated sensitivity of TC limiting intensity to SST, and 2) explore possible explanations for any differences that exist. Observed TC data are compared to simulated TCs from four different GCMs---the FSU-COAPS, GFDL-HiRAM, MRI-AGCM, and NCAR-CAM. Model horizontal grid spacing ranges from ~100 km for the FSU-COAPS to ~20 km for the MRI-AGCM. An additional comparison is made for TCs generated through a statistical-deterministic downscaling technique. This research uses a spatial tessellation approach that spatially bins North Atlantic TC and SST data into equal-area hexagon regions. For each region, the statistical upper limit of observed and simulated TC intensity (i.e., limiting intensity) is estimated using extreme value theory. For comparison with the statistical limiting intensity, reanalysis and model field data are employed to approximate observed and simulated potential intensity, respectively. Results reveal that the current suite of GCMs do not capture the observed sensitivity of TC limiting intensity to SST. While a 1° C increase in SST corresponds to a 7.9 +/- 1.19 m/s increase in observed limiting intensity, the same 1° C increase in SST is not associated with a statistically significant increase in simulated TC limiting intensity. This is found to be true both for relatively coarse resolution GCMs that do not generate TCs with intensities exceeding 50 m/s as well as for higher resolution GCMs that are capable of simulating Category 5 hurricanes. Rather than SST, it is found that simulated TC limiting intensity is highly sensitive to 700--400 hPa relative humidity. Conversely, relative humidity does not describe any of the residual variance in observed TC limiting intensity. Therefore, this research suggests that even if a model is able to resolve realistically strong TCs, those simulated TCs may not be governed by the same thermodynamic principles as those that we observe. Although GCMs do not capture the observed sensitivity of limiting intensity to SST, it is shown that the FSU-COAPS model capably reproduces the observed sensitivity of potential intensity to SST. The model generates a thermodynamic environment suitable for the development of strong TCs over the correct portions of the basin, however strong simulated TCs do not develop. This result strongly supports the notion that direct simulation of TC eyewall convection is necessary to accurately represent TC intensity and intensification processes in climate models. / A Dissertation submitted to the Department of Geography in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Spring Semester, 2015. / February 27, 2015. / Global climate models, Tropical cyclones / Includes bibliographical references. / James B. Elsner, Professor Directing Dissertation; Henry Fuelberg, University Representative; Chris Uejio, Committee Member; Tingting Zhao, Committee Member.

Violent tropical cyclones (TCs) continue to inflict serious impacts on national economies and welfare, but how they are responding to global warming has not been fully clarified. Here I construct an empirical framework that shows the observations supporting a strong link between rising global ocean warmth and increasing trade-off between TC intensity and frequency in the western North Pacific. Thermodynamic structure of the tropical western North Pacific with high global ocean warmth is characterized by convectively more unstable lower troposphere with greater heat and moisture, but this instability is simultaneously accompanied by anomalous high pressure in the middle and upper troposphere over the same region. Increasing trade-off level between TC intensity and frequency in a warmer year proves that this environment further inhibits the TC occurrences over the region, but TCs that form tend to discharge stored energy to upper troposphere with stronger intensities. By increasing the intensity threshold at higher levels we confirmed that the TC climate connection with global ocean warmth occurs throughout the strongest portion of TCs, and the environmental connection of the TC climate is more conspicuous in the extreme portion of TCs. Intensities at the strongest 10~% of the western North Pacific TCs are comparable to super typhoons on average, the increasing trade-off magnitude clearly suggests that super typhoons in a warmer year gets stronger. Conclusively, the negative collinear feature of the thermodynamics influences the portion of TCs at the highest intensities, and super typhoons are likely to become stronger at the expense of overall TC frequencies in a warmer world. The consequence of this finding is that record-breaking TC intensities occur at the expense of overall TC frequencies under global warming. TC activity is understood as a variation which is independent of global warming, and could be assumed to be an internal variability having no trend. Frequency variation and super typhoon intensity variation are regarded as the addition of global warming influence on TC activity variation. The structure depicts how a previous intensity record is overtaken and frequency falls continuously in the global warming environment in a linear perspective. A peak TC activity year when global ocean warmth is the highest ever is likely to experience a record-breaking intensity. In the same way, the least number of annual TCs may appear when a lull of TC activity occurs in the warmest year. / A Dissertation submitted to the Geophysical Fluid Dynamics Institute in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester, 2014. / August 25, 2014. / efficiency of intensity, global warming, super typhoon, Tropical cyclone climate / Includes bibliographical references. / James B. Elsner, Professor Directing Dissertation; Robert Hart, University Representative; Kevin Speer, Committee Member; Mark Bourassa, Committee Member.

African Easterly Waves (AEWs) are mesoscale synoptic features that form in West Africa and propagate westward. The relationship of AEWs to rainfall in the region has been examined in previous studies but no scientific consensus has been reached. This relationship, however, has been found to be complex and to involve numerous feedback mechanisms such as the African Easterly Jet (AEJ) fluctuations. Other mechanisms like latent heat release and the temperature gradient at the surface between the dry Sahara Desert and the moist maritime region along the Gulf of Guinea also play a role in the relationship between rainfall and AEWs. This study will investigate the relationship of AEWs to rainfall through objective analysis of the waves and an EOF analysis of daily rainfall over a prescribed region. Two classification schemes along with statistical techniques were used to investigate the spatiotemporal variability of the relationship between African Easterly Waves (AEWs) and the rainfall over West Africa. Two varying methods were used because of the highly subjective manner of tracking AEWs. This study was limited to four wet years (1958 –1961) and four dry years (1982-1985) during the summer months of June, July, August and September. The first technique was a new three-step method designed by Dr. A. Fink that makes use of 700mb and 850mb streamline plots and band-pass filtered meridional wind data. The second method uses the vertical structure of the band-pass filtered meridional wind to identify wave passage. The methods were compared and contrasted with one another, and both were shown to be adequate for tracking AEWs. However, for examining the relationship of rainfall with AEWs the second method appropriately named the Vertical Profile Method (VPM) was found to be preferable. Using the VPM the difference between wave characteristics and rainfall variability were examined on a daily timescale. This involved creating daily rainfall datasets for four different quadrants over the Sahel and relating any changes in rainfall activity to the AEWs as they both propagated across the quadrants. The differences in AEW and rainfall characteristics were examined by making comparisons within two distinct time-frame perspectives. The first perspective examined differences between wet and dry years and the second perspective examined differences between the 1st two months (June-July) and the last two months (August-September). For each category the strength of the waves, number of waves, location of the north and south regime, rainfall distribution and rainfall amounts were compared. During the wet years (1958 -1961) the number of waves that propagated across West Africa averaged 59 waves per year using the Vertical Profile Method (VPM) and 49 using the Andreas Fink Method (AFM). The number of AEWs tracked during the dry years (1982-1985) averaged about 63 with the VPM and 54 with the AFM. The difference in the average number of AEWs between the methods was probably a result of the limitations of each method. More waves in the dry years supports previous conclusions that stronger but less frequent AEWs occur in wet years and weaker but more frequent AEWs occur in the dry years. Tracking of the AEWs also allowed for the separation of the AEWs into two distinct wave regimes north and south of the African Easterly Jet (AEJ). Throughout all eight years the separation became apparent as the summer progressed with the separation reaching a maximum. This coincides with the fluctuations in AEJ intensity, which also has a maximum in the month of August. Rainfall within the tracked AEWs was found to be bimodal with the region of maximum northerly flow containing the most rainfall. This region is ahead of the trough and is typically associated with squall line convective activity. The maximum region was the same for both wet and dry years and also for the two month season comparison. An EOF analysis of daily rainfall was completed for 1958 (wet year) and 1983 (dry year) to determine if any relationship to AEWs could be identified in the rainfall time series. The resulting eigenvalues show the influence of topography along the Guinea coast with positive values: however, no discernable link to AEWs was present. The power spectrum of the first two principle components did identify a significant peak at the same period associated with AEWs. This power spectrum analysis demonstrated that rainfall is linked to AEWs, but a more detailed dynamical investigation is needed. / A Thesis Submitted to the Department of Meteorology in Partial Fulfillment of the Requirements for the Degree of Master of Science. / Spring Semester, 2006. / December 8, 2005. / Daily Rainfall, African Easterly Waves, EOF / Includes bibliographical references. / Sharon E. Nicholson, Professor Directing Thesis; T. N. Krishnamurti, Committee Member; Kwang-Yul Kim, Committee Member.

The objective of this study was to investigate oxygen consumption rates in permeable Gulf coast sediments and their link to changes in the water and sediment chlorophyll concentrations. The investigation was initiated to improve our understanding of the biogeochemical functioning of these sediments and their role in the coastal cycling of organic matter. Although sand is the most abundant sediment type on the continental shelf, the decomposition process in sediments affected by advective pore water exchange is not understood. Boundary-layer flows transport organic matter, nutrients and electron acceptors into nearshore permeable sediments thereby affecting benthic photosynthesis, microbial activity and oxygen dynamics. A series of advection chamber measurements was used to determine temporal and spatial variations in O2 consumption at two study sites located in the Northeastern Gulf of Mexico, with one site located at the exposed south side of St. George Island and the other more sheltered site in Apalachicola Bay. A time series analyzing sediment cores and overlying water samples provided data on the temporal and spatial dynamics of sedimentary and water column chlorophyll and oxygen concentrations. Sediment grain size and porosity were similar at the two sites, although Gulf sediments in general were more permeable (Gulf: 1.84 x10-11 to 5.29 x10-11, Bay 7.3x10-12 to 2.11x10-11) and had higher chlorophyll content at the Bay side (Gulf: 1.1 to 10.6 μg cm-3, Bay: 8.8 to 47.2 μg cm-3). At the Gulf site, O2 consumption rates ranged from 2 mmoles m-2 d-1 in winter to 17 mmoles m-2 d-1 in summer, while at the Bay site a maximum of 62 mmoles m-2 d-1 was recorded in August 2006 and a minimum of 11 mmoles m-2 d-1 in the winter. These rates demonstrate high metabolic activity in Gulf of Mexico nearshore sands despite their relatively low content of labile organic matter as reflected by their chlorophyll concentrations. Bay sediment chlorophyll in the upper 3 cm reached highest values in spring (March 2007: 47 μg cm-3), and the Gulf site in summer (July 2006: 10 μg cm-3). Our results highlight the role of filtering sublittoral sands as sites for high benthic organic matter turnover. / A Thesis submitted to the Department of Oceanography in partial fulfillment of the requirements for the degree of Master of Science. / Fall Semester, 2008. / October 22, 2008. / Oxygen Consumption, Marine Sediments / Includes bibliographical references. / Markus Huettel, Professor Directing Thesis; Thorsten Dittmar, Outside Committee Member; Richard Iverson, Committee Member.

For many years tropical cyclone superensemble has shown remarkable skill in forecasting Atlantic tropical cyclone track and intensity. In this project tropical cyclone superensemble is applied to Eastern Pacific tropical cyclone forecasting for the 2004 Eastern Pacific tropical cyclone season. This task is completed by conducting a collection of model combination tests to discover which models perform best within the superensemble method. Then, the two main questions of this thesis are addressed: will a combined Eastern Pacific and Atlantic training set provide superior forecasts over just using an Eastern Pacific training set, and do intensity-specific training sets provide superior forecasts over just using all storms of varying intensities? In the context of the 2004 Eastern Pacific tropical cyclone season, the answer to both questions is yes. However, the ultimate findings are quite perplexing, as an Atlantic training set provides superior forecasts when compared to forecasts using an Eastern Pacific training set or a combined-basin training set. Furthermore, forecasts made using only hurricane training usually outperform forecasts made using combined-intensity training and tropical storm training. The rest of the project uses model bias comparisons and intensity-specific error calculations to try and determine why the results are as they are. / A Thesis submitted to the Department of Meteorology in partial fulfillment of the requirements for the degree of Master of Science. / Fall Semester, 2005. / September 1, 2005. / Tropical Cyclone Forecasting, Hurricanes / Includes bibliographical references. / T. N. Krishnamurti, Professor Directing Thesis; Carol Anne Clayson, Committee Member; Peter S. Ray, Committee Member.

Atmosphere-biosphere exchange plays a key role in the global cycles of water and carbon. Air pollution can alter these processes and induce climate perturbations and feedbacks. Surface ozone (O3) is an air pollutant and greenhouse gas that is toxic to plants, reducing their growth and ability to regulate water loss. Past controlled experiments have shown that O3 degrades a plant's water-use efficiency (WUE), which is the ratio of carbon uptake in photosynthesis to water loss in transpiration. This has potentially significant implications for terrestrial water cycle and precipitation, but no studies have evaluated the O3 effect on WUE in complete ecosystems. We aim to quantify the impact of O3 on WUE across a wide array of ecosystems. Meteorological and biological data was obtained from 23 FLUXNET flux tower sites, which use the eddy covariance method to derive hourly fluxes of carbon dioxide (CO2), water vapor (H2O), and O3 between the atmosphere and ecosystem. Across a broad range of sites, we find a significant negative relationship between daily anomalies of stomatal O3 flux (FS, O3) and WUE that explains 1-3% of WUE variability. The largest impacts occur in locations and species with high stomatal conductance, such as broadleaf forests, humid climates, or irrigated crops, rather than where surface O3 concentrations are highest. Past long-term studies have also found similar O3 impacts (1-3%) on WUE, indicating a consistent response across a pool species and ecosystems. / A Thesis submitted to the Department of Earth, Ocean, & Atmospheric Science in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester 2016. / March 23, 2016. / Ecosystems, FLUXNET, Natural environments, Stomatal ozone flux, Water-use efficiency / Includes bibliographical references. / Christopher D. Holmes, Professor Directing Thesis; Stephanie Pau, Committee Member; Vasu Misra, Committee Member; Jon Ahlquist, Committee Member.