Stable isotopes of oxygen, carbon and nitrogen were used to understand the ecological changes induced by human activities. The existing method developed by McLaughlin et al. (2004) for determination of the oxygen isotopic composition of dissolved phosphate (DIP) is not directly applicable to organic-rich waters in the Florida Everglades and produced Ag3PO4 precipitates contaminated by high amounts of organic matter. A series of laboratory tests was conducted to reduce the amount of organic contaminant in Ag3PO4 prepared from organic-rich DIP samples and to improve the accuracy of oxygen isotopic analysis of DIP. The improved method reduces the organic contamination in the final Ag3PO4 precipitates by more than 10 fold (from >20% C to ~2% C) compared to the previous method and can be used to accurately determine the oxygen isotopic composition of DIP in organic rich aquatic ecosystems if the oxygen isotopic difference between the DIP and dissolved organic matter is less than 13‰.20% C to ~2% C) compared to the previous method and can be used to accurately determine the oxygen isotopic composition of DIP in organic rich aquatic ecosystems if the oxygen isotopic difference between the DIP and dissolved organic matter is less than 13‰. The improved method was used to examine the oxygen isotopic systematics of DIP and to identify P sources and recycling in the Everglades. Our data reveal seasonal variations in the &delta18O of DIP, with lower values in the summer and higher values in the winter. Our results show that the &delta18O values of DIP collected from the Everglades National Park are in equilibrium with environmental water. This indicates that phosphorus (P) is quickly recycled in areas with low P concentrations. However, most DIP samples collected from areas impacted by high P loading are not in oxygen isotopic equilibrium with water, suggesting that biological cycling of P is not fast enough to erase the "fertilizer" &delta18O signature in the DIP pool in areas with high P levels. Using a two-endmember (i.e., fertilizer P and biologically recycled P) mixing model, we estimated that less than 57.5% of the DIP was derived from fertilizer. The &delta18O of total P (&delta18OTP) in sediments suggests at least three P resources: organic P with depleted 18O, fertilizer P with &delta18O values of ~23.7‰, and bacteria-processed P with &delta18O of ~16 to 24‰ at 20 to 30°C. Our data also show that the sediment P is dominated by organic P. The &delta18O of DIP displayed significant negative correlations with precipitation and evapotraspiration, underscoring the importance of hydrological factors in controlling the P cycle. Stable isotopes of carbon and nitrogen were used to trace the source of carbon and nutrients and to investigate the food web structure in Missouri River. Our data show that all the fish depend on the same carbon source and there exists significant dietary overlap between the invasive Asian carps and the native filter-feeding fishes. The similarity of &delta13C values of particulate organic matter and the fish muscle tissue indicate that the food base of the filter-feeding fishes was particulate organic matter in the water column. Bighead carp, the hybrids, gizzard shad, silver carp and bigmouth buffalo have trophic positions of 2.9, 2.9, 3, 2.1 and 2.6, respectively. Bighead carp and the hybrids compete with paddlefish for zooplankton and silver carp compete with gizzard shad for algae and detritus. Understanding the competitions between the invaders and native species can help policy makers and ecosystem managers to better manage the aquatic system. / A Dissertation Submitted to the Department of Geological Sciences in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy. / Summer Semester, 2009. / April 29, 2009. / Oxygen, Phosphorus, Nitrogen, Carbon, Isotope / Includes bibliographical references. / Yang Wang, Professor Directing Dissertation; Jeffrey Chanton, Outside Committee Member; Xiaolong Bill Hu, Committee Member; A. Leroy Odom, Committee Member.

Rapid intensity changes in hurricanes have been the focus of many publications. Understanding how and why these storms intensify has been the goal of many meteorologists over the last few years. This study explores the energetics of Psi-Chi interactions in modeled hurricanes of rapidly changing intensity. The energy exchanged within the storm as the flow changes from divergent to rotational is known as Psi-Chi interactions. Processes associated with latent heant and sensible heat exchanges are important when it comes to identifying changes in hurricane intensity. Understanding this interaction with the environment is crucial to understanding how the intensity changes. Model data derived from the fifth generation model from NCAR/Penn State known as the MM5 is used to calculate each term within the Psi-Chi equation. Each term is then calculated within the storm and its maximum values as well as location of maximum values within the storm are noted. The maximum value of each term and location of each term allows for an investigation of a connection between the energy exchange of the storm and its intensity. The maximum values of the terms of Psi-Chi interactions are also compared to the model intensity of each storm. Based on the comparison of model intensity and maximum term values there appears to be a strong relationship between the two (correlation values near r = 0.87), although further study is needed to determine if this simultaneous relationship can be extended to a lagged relationship to provide predictive value to forecasters. / 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. / Summer Semester, 2011. / March 7, 2011. / Hurricane, Psi Chi, Intensity / Includes bibliographical references. / T. N. Krishnamurti, Professor Directing Thesis; Robert E. Hart, Committee Member; Vasubandhu Misra, Committee Member.

The lack of satellite imagery prior to 1966 and limited aircraft reconnaissance has led to an indefinite number of tropical cyclones (TCs) in the Atlantic Basin remaining undetected by traditional surface observational networks. As a result, these cyclones were not identified by operational forecasting centers like the National Hurricane Center and are not a part of the consensus Atlantic TC climatology. While previous research suggests that this historical undersampling exists, there is considerable disagreement as to its true magnitude. However, it is widely accepted that these "missing storms" have led to difficulties in interpreting long-term trends in TC activity, adding uncertainty to the dialogues over the nature, role, and existence of the Atlantic Multi-decadal Oscillation and the possible influence of climate change on TC activity, among many others. This research seeks to add information to Atlantic Basin TC climatology by developing a scheme to identify previously unknown potential cyclones in the pre-satellite era. The technique utilizes advances in global reanalysis methods to identify candidate events within certain probabilistic bounds in order to improve existing TC Best-Track reanalysis efforts. Briefly, a series of thermodynamic proxies of TC passage in the NOAA/CIRES 20th Century Reanalysis dataset is first constructed. Signatures in these metrics that are of similar amplitude and morphology to known TCs but do not correspond to known Best-Track cyclones are identified within the reanalysis solution for the test hurricane seasons of 1951 through 1958. Synoptic verification of these candidate events using historical surface observation datasets sorts the events into three broad confidence bins. The most common outcome of the observational verification process is that the candidate event does not represent a credible possible addition to BT climatology. However, a small but significant number of the candidate events were found to present highly compelling cases for further examination by ongoing TC climatology revision efforts and may eventually warrant addition to the Best-Track database. Several of these candidate events, representing a broad range of possible uses of the technique, are presented in detailed case studies. Additionally, application of the reanalysis-based methodology to the Eastern Pacific Basin demonstrates promise for use in other TC basins around the world. In general, results suggest that future work extending the technique developed in this research may potentially lead to a more complete climatological record of global TC incidence and an improved understanding of long-term trends in activity. / 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, 2011. / March 28, 2011. / Tropical Cyclones, Climatology, Reanalysis / Includes bibliographical references. / Robert Hart, Professor Directing Thesis; Carol Anne Clayson, Committee Member; Henry Fuelberg, Committee Member.

The low-frequency signals (LFS) of climate variables such as temperature and pressure often contain variability as a result of the nonlinear and non-stationary nature of Earth's climate system. Occasionally, as in the case of the North Pacific climate regime shift of the mid-1970s, this variability appears in the form of an abrupt shift in climate states. Because such variability can have large impacts on agriculture, wildfire frequency/intensity, and ecological systems, it is important to pursue a more complete understanding of low frequency climate interactions. Previously, techniques such as fourier, windowed fourier, and wavelet analyses were used to extract the LFS. However, these techniques rely on an assumption of linearity, and thus when applied to nonlinear climate data, can potentially cloud the physical meaning of the extracted LFS. In this study a recently developed adaptive and temporally local analysis method—ensemble empirical mode decomposition (EEMD)—is applied to extract the LFS from observed daily minimum temperature data. The analysis uses data from 115 weather stations scattered throughout North Carolina, South Carolina, Georgia, Alabama, and Florida for the period from 1955 through 2007. An EOF analysis of the minimum temperature LFS reveals a large drop in the first PC time series in the mid-1970s. Further EOF-based analysis of the low-frequency variability leads to different interpretations of the characteristics of surface temperature variability. Most notably, the widely recognized shift of low-frequency variability around the mid-1970s can be alternatively interpreted in the Southeastern United States as phase coincidence between individual quasi-oscillatory components of interannual to decadal timescales. / 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, 2011. / March 21, 2011. / Low-frequency variability, Climate variability, Climate regime / Includes bibliographical references. / Zhaohua Wu, Professor Directing Thesis; Vasu Misra, Committee Member; Philip Sura, Committee Member.

Carbon isotopes were used as tracers in the Florida Everglades to investigate the sources and sinks of dissolved organic carbon in natural and constructed wetlands and provide a way to monitor ecosystem restoration efforts. Stable carbon isotopes were used to determine the source of DOC and POC, and in a basic mass balance model to calculate turnover times of DOC in small constructed wetland cells. Radiocarbon was used to distinguish "old" DOC derived from historic peats from "new" DOC derived from modern primary production. Our study suggests that Ä14C measurements can be a useful indicator of the progress of ecosystem restoration in the Everglades. The oxygen isotope of phosphate (P) can also serve as an isotopic tracer in wetlands. Initial method development to use the oxygen isotope of phosphate extracted from natural waters is presented here. Preliminary data indicates that microbial recycling is a major means by which P stays in the water column despite reducing anthropogenic contributions. Stable carbon isotopes were also used to quantify the percent of methane oxidized within Tallahassee landfill soils. Carbon isotope and oxidation data collected over almost 9 months of monitoring methane emissions from landfill surfaces with and without a "biocover" is examined. These measurements, combined with measurements of methane flux, can help monitor the efficiency of various treatments in reducing methane emissions to the atmosphere by enhancing oxidation of methane by methanogenic bacteria. The presence or absence of DOC in the water column can determine whether trace metals will be present as a nutrient or as a toxicant. A novel method coupling capillary electrophoresis with ICP-MS was used to separate metal species and calculate binding constants of rare earth elements and Th, Hf, and Zr with humic substances at a range of pH and ionic strength of 0.1. Equilibrium dialysis ligand exchange was performed to validate the CE-ICP-MS method. Conditional stability constants of tetravalent metal-HA complexes are several orders of magnitude higher than lanthanide-HA complexes. Because thorium is often used as a proxy for the tetravalent actinides, Th-HA binding constants are useful in the study of sequestration of actinides in nuclear repository settings. / A Dissertation Submitted to the Department of Geological Sciences in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy. / Summer Semester, 2005. / April 28, 2004. / Metal speciation, Humic acid, Thorium, Capillary electrophoresis, CE-ICP-MS, Landfill Methane, Phosphorus, Everglades, Carbon isotopes / Includes bibliographical references. / Yang Wang, Professor Co-Directing Dissertation; Vincent J.M. Salters, Professor Co-Directing Dissertation; Jeffrey Chanton, Outside Committee Member; A. Leroy Odom, Committee Member.

Modern (farmed) calcite in Hollow Ridge Cave, Marianna, FL, USA was cultivated seasonally and analyzed for isotopic composition (δ18O and δ13C). Simultaneous in situ cave-air chemistry, drip water composition, and micrometeorology were continuously monitored to unravel the connection between the depositional timing and isotopic composition of calcite and ventilation-driven changes in cave-air CO2. Multi-year collection of soil gas, atmospheric and cave-air CO2 samples and drip waters allow the prediction of dripwater calcite saturation state, and thus speleothem precipitation, as a function of cave-air pCO2. This study demonstrates that high summer-time cave air pCO2 inhibits calcite growth, and that deep interior Hollow Ridge Cave speleothems preserve winter-time paleoclimate signals. This work also demonstrates the existence of a relationship between ventilation, evaporation and rapid CO2 loss on modern Hollow Ridge Cave calcite. Furthermore oxygen isotopic composition of Hollow Ridge calcite exhibits a constant positive offset from both the O'Neil et al. (1969) and Kim & O'Neil (1997) inorganic calcite temperature equations, allowing the construction of a new temperature equation for speleothem calcite that describes both temperature and ventilation fractionation effects on speleothem precipitation. This study illustrates the value of investigating site-specific drip water and cave-air chemistry before making speleothem-based interpretations of paleoclimate. This study has also provided a valuable link between rainfall, epikarst saturation state, and modern drip water residence time and x/Ca element partitioning in both water and calcite. It was observed that each site of calcite growth inside HRC has a unique chemistry in terms of x/Ca vs. Mg/Ca ratios. The data at each site are representative of a two endmember mixing system; (1) calcite dissolution during wetter epikarst periods, and (2) rainfall dilution. Sites can clearly be chemically grouped which suggests that down-slope hydrology and water residence time partially control the chemistry of drip water at HRC. Distribution coefficients were established for HRC calcite, and by comparing x/Ca vs Mg/Ca in drip waters with x/Ca vs. Mg/Ca in calcite it was determined that Li, Sr, K, U and Si are suitable modern-day solid-phase indicators of the hydrological conditions in the epikarst above HRC. This study also established that Na, Mn and Ba are not suitable standalone paleohydrologic proxies, but may be useful indicators when used together. / A Thesis Submitted to the Department of Oceanography in Partial Fulfillment of the Requirements for the Degree of Master of Science. / Summer Semester, 2010. / May 5, 2010. / Paleoclimate, Speleothem, Cave, Isotopes, Trace Element / Includes bibliographical references. / Philip N. Froelich, Professor Directing Thesis; Yang Wang, Committee Member; Doron Nof, Committee Member; Allan Clarke, Committee Member; Bill Burnett, Committee Member.

The Atlantic Warm Pool (AWP) is located in the western tropical North Atlantic (TNA) and the Intra-Americas Sea (IAS) (the Gulf of Mexico and the Caribbean Sea). The AWP is an area of warm sea surface temperatures (SSTs) greater than 28.5°C that exhibits a strong seasonal cycle, with the AWP disappearing in boreal winter (December-January-February) and reaching a maximum in late boreal summer (August-September-October (ASO)). In addition, the AWP exhibits interannual variability, with large AWPs nearly three times larger in area than small AWPs. Because there is a lack of surface and subsurface observations in the IAS and the TNA, this study uses reanalysis products to examine the AWP. It is of interest to ask what is the quality of these reanalysis products in their examination of the AWP. Thus, the main objective of this study is to examine and intercompare different reanalysis' renditions of the AWP. Three ocean reanalysis products are examined in this study and they are the following: (1) the Global Ocean Data Assimilation System (GODAS), (2) the Climate Forecast System Reanalysis (CFSR), and (3) the Simple Ocean Data Assimilation (SODA). In addition, because GODAS and SODA are not coupled to the atmosphere whereas CFSR is, two atmospheric reanalysis products are also used and they are the following: (1) the NCEP–National Center for Atmospheric Research (NCAR) reanalysis (hereafter R1), and (2) the NCEP–Department of Energy (DOE) Atmospheric Model Intercomparison Project (AMIP-II) reanalysis (hereafter R2). R1 is used in conjunction with SODA, and R2 is used in conjunction with GODAS. The period of interest for this study is 1980−2006. Each ocean reanalysis is used to examine the annual and interannual variability of the AWP in ASO. In addition, GODAS with R2, CFSR, and SODA with R1 are used to perform a detailed analysis of the SST tendency equation of the AWP. Furthermore, GODAS with R2, CFSR, and SODA with R1 are used to examine the impact of the AWP on the tropical tropospheric temperature and see if the impact is similar to the impact seen by the El Niño Southern Oscillation (ENSO). All three ocean reanalyses depict similar annual variability of the AWP. They all exhibit the AWP to be non-existent in boreal winter (December-January-February) and at a maximum in boreal summer. However, the reanalyses are inconsistent in their initial appearance of the AWP. All three ocean reanalyses depict similar interannual variability of the AWP; however, they are inconsistent in the relationship between the AWP area and subsurface temperatures. From the SST tendency equation, the fluxes contribute more to the AWP SST tendency in GODAS and CFSR, and the fluxes act to remove heat from the AWP. In SODA, the advective terms contribute more to the AWP SST tendency. Additionally, the reanalyses show that the AWP warms the tropical troposphere contemporaneously (ASO) but not three to six months after, as in the case with ENSO. / A Thesis Submitted to the the Department of Earth, Ocean and Atmospheric Science in Partial Fulfillment of the Requirements for the Degree of Masters of Science. / Summer Semester, 2011. / July 5, 2011. / Wang, lead-lag, Contemporaneously, Correlations, Tendency / Includes bibliographical references. / Vasubandhu Misra, Professor Directing Thesis; Robert Hart, Committee Member; Mark Bourassa, Committee Member.

Past binary logistic regression (BLR) and perfect prognosis schemes have shown skill for predicting the probability of one or more cloud-to-ground (CG) lightning flashes for regions such as Florida. This study examines the ability of the BLR and perfect prog techniques to forecast only those flashes at the daily onset of warm season convective activity. A statistical model is developed for two domains in the western United States in the vicinities of Amarillo, Texas and Albuquerque, New Mexico, to predict the probability of one or more CG flashes during the 1800 UTC to 2100 UTC time window. Warm season convection in these locales is influenced by factors such as the Southwest Monsoon, drylines, and topography. Each domain consisted of a 28 × 26 grid at a 10-km resolution. One equation for each domain was developed using 10-year climatology and predictors from the North American Regional Reanalysis (NARR) dataset for the dependent period May through September of 1994 – 2004. In our perfect prog scheme, the reanalysis data were treated as observations. Forecasts were made for the 2005 warm season, and evaluated using the Brier Score, Brier Skill Score, and reliability diagrams. Due to the relative rarity of the event being forecast, forecast probabilities tended to be small, rarely exceeding the 30% range in the Amarillo domain and 70% (with a majority below 50%) in the Albuquerque domain. Both domains typically exhibited skill over climatology and good reliability for low forecast probabilities, which constituted a majority of the forecasts. Sample forecasts for both domains are examined. The Amarillo model demonstrated competent performance on 10 June 2005, but poor performance on 1 September 2005. The Albuquerque model performed well on 1 September 2005, but performed poorly on 17 July 2005. Despite the low magnitude of probabilities forecast, both models showed promise, commonly placing their relative maxima in the vicinity of the verifying initiating flashes, with some obvious exceptions. / 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. / Summer Semester, 2011. / August 24, 2007. / Statistical Modeling, Forecasting, Lightning / Includes bibliographical references. / Henry E. Fuelberg, Professor Directing Thesis; Jon Ahlquist, Committee Member; Paul Ruscher, Committee Member.

Particle-laden buoyant jets (PBJ) are free-convective flows that contain particles. Many studies have examined pure thermal plumes, discussing a symmetric self-similar structure that is common in the plume literature. Other studies have studied the fallout properties of particles embedded in plumes. Many contaminant transport models use a Gaussian, self-similar plume profile and treat particles only as a passive tracer. There is however no evidence in the literature of the simultaneous examination of both particle loading and temperature on the flow regimes of a PBJ. Twenty-five numerical simulations were implemented using the LANL HIGRAD numerical model, to systematically study the resulting flow regimes as the temperature and particle loading of a PBJ were systematically varied. A supplemental experiment was carried out in the laboratory, with three simulations carried out that were dynamically similar to the experiment. The comparison between experiment and simulation indicated that the model did not create turbulence as close to the domain floor as in the experiment, and further tuning is required. With awareness of this inconsistency, the twenty-five simulation results produced results of significant interest. Only two of the twenty-five simulation results produced the self-similar, Gaussian profile that is observed in the plume literature. Four of the twenty-five cases produced a no collapse PBJ scenario. The remaining cases produced either a partial collapse or full collapse of the PBJ. The use of the Grashof and buoyant Richardson numbers to characterize the flow regimes did not produce consistency with the resulting flow regime. A modified multiphase Richardson number however, accounting for particle density within a control volume, showed consistency with the resulting flow regime and indicates promise for further research and perhaps operational use. PBJ are physically relevant to a variety of particle-laden convective flows including volcanoes, industrial emissions, and contaminant transport. These results are of interest to a number of stakeholders including the DOE, DOD, DHS, and emergency management communities. / A Dissertation Submitted to the Department of Meteorology in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy. / Summer Semester, 2010. / April 29, 2010. / Particles, Plumes, Buoyant Jets, Convective, HIGRAD / Includes bibliographical references. / Paul Ruscher, Professor Directing Dissertation; James B. Elsner, University Representative; Carol Anne Clayson, Committee Member; Henry E. Fuelberg, Committee Member; Guosheng Liu, Committee Member.

Coherent Tropopause Disturbances (CTD's) have been observed to play a central role in both extratropical cyclogenesis and the dynamics of jet streaks. Recent observational studies have quantified the existence of CTD's by locating potential temperature minima on a constant potential vorticity surface that is representative of the dynamic tropopause. This study applies a similar approach, but to a data set from a high-resolution global model (the Community Climate Model, Version 3). Application of an objective identification and tracking algorithm, along with several statistical calculations involving potential temperature on the 2.0 PVU surface, with statistics of outgoing longwave radiation, indicate that the CCM3 is a tool that may yield valuable insight into the dynamical interactions that determine the origin, growth and lifecycles of CTD's. / 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 28, 2006. / CTD, Coherent Tropopause Disturbances, Diabatic Potential Vorticity, Jet Amplification, Jet Dynamics, Tropopause, Potential Vorticity, Vortex / Includes bibliographical references. / Philip Cunningham, Professor Directing Thesis; Robert Hart, Committee Member; T. N. Krishnamurti, Committee Member; Paul Reasor, Committee Member.