Sea Surface Temperatures (SSTs) are an important measure of our current weather and climate, as well as an essential variable in both short and long term weather forecasting. Infrared SST retrievals are reliant on passive sensors, and retrieval techniques are influenced by changes in atmospheric composition, including aerosols. Many empirically derived retrieval algorithms are based on matching Top of Atmosphere (TOA) Brightness Temperatures (BTs) from the Advanced Very High Resolution Radiometer (AVHRR) to buoy measurements during clear-sky conditions. Data is cloud-cleared to remove cloud-contaminated data. However, small, but influential, Aerosol Optical Depths (AODs) data may not be flagged as contaminated and the algorithms incorrectly calculate a cold SST due to the radiometer sensing the cooler, elevated aerosol layer temperature. Many studies on aerosol effects on SSTs focus on aerosols due to volcanic eruptions. However, truly operational tropospheric aerosol corrections for daytime and nighttime retrievals have yet to be implemented. This work constitutes a first step to creating an accurate aerosol correction by exploring the sensitivity of aerosols on SSTs. The Santa Barbra DISORT Radiative Transfer model is used to quantify the effects of aerosol contamination on retrieved TOA BTs. The calculated radiances are spectrally averaged over each channel, converted to BTs, and used to calculate an SST using the Naval Oceanographic Office AVHRR algorithms. A radiative transfer model is used to evaluate the SST retrieval error due to varying AOD, height of an aerosol layer, and the satellite zenith angle (or viewing angle). This analysis shows that errors greater than the stated retrieval uncertainty of 0.5 K are observed for AODs greater than 0.25. Two sites with state-of-the-art aerosol measurements are analyzed for AOD variability. The first site, at Anmyon in east Asia, is found to have 14% of the days during the springtime with an AOD greater than 0.25. Based on the AERONET data from a second site in Cape Verde, 65% of the days during the boreal summer are found to have AOD greater than 0.25. Unfortunately, this seasonal peak in dust activity coincides with the active tropical cylogensis season for the region, making accurate SSTs even more vital for prediction purposes. / 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. / October 19, 2010. / Dust, Retrieval Error, Aerosols, Sea Surface Temperature / Includes bibliographical references. / Carol Anne Clayson, Professor Directing Thesis; Mark A. Bourassa, Committee Member; Guosheng Liu, Committee Member; Douglas L. Westphal, Committee Member.

By sampling individual rain events over a 1-year period at three sites situated around a known point source of atmospheric mercury, we have attempted to quantify its influence on local mercury deposition. A suite of trace elements was also analyzed on these rain event samples. A multi-element analytical program was set up using a Thermo-Finnigan "Element" ICP-MS. We identified 46 elements that are significantly enriched in rain samples relative to the method blank, including the alkali metals and alkaline earth elements, all three rows of the transition metals, and the rare earth elements. The total mercury concentrations in the rainwater samples ranged from 2-40 ng/L. The volume weighted mean rainfall mercury concentrations ranged from 9.2-9.8 ng/L, and there were no significant differences in the rainfall Hg deposition between the three sites. Principal component factor analysis (PCFA) was used to evaluate co-variance between mercury and trace element deposition. PCFA showed a strong crustal factor, a strong sea-salt factor, a mysterious "P" factor and a strong mercury factor. The mercury factor linked mercury with Bi, Ga, Pb, Sb and V. Plume dispersion modeling and air-mass back trajectory analysis have been conducted for each rain event. The goal of this research was to use mercury and trace element relationships in an effort to identify, and quantify, the impacts from various emission sources in the region on rainfall chemistry. We calculated the annual integrated percent of mercury associated with coal burning ranging between 15-47%. Using models to estimate the impact of local deposition we found that less than 1% of the mercury we measured is from the known point source. / A Thesis submitted to the Department of Oceanography in partial fulfillment of the requirements for the degree of Master of Science. / Fall Semester, 2006. / July 14, 2006. / Pensacola, Trace Metal, Florida, Hg, Coal Fired Power Plant / Includes bibliographical references. / William M. Landing, Professor Directing Thesis; Philip Froelich, Committee Member; Markus Huettel, Committee Member.

This dissertation is a collection of five calcareous nannofossil and one stable isotope studies on materials from Ocean Drilling Program (ODP) Legs 183 (Site 1135), 206 (Site 1256), and 207 (Site 1259) that target two important paleoceanographic events: 1) the middle/late Miocene carbonate crash, and 2) the Paleocene/Eocene Thermal Maximum (PETM). Site 1256 nannofossil biostratigraphy in Chapter 1 refined the author's shore-based shipboard Quaternary-middle-Miocene nannofossil biostratigraphy with 16 zones/combined zones recognized based on 28 nannofossil datums. This chapter provides a chronologic framework for the age calibration of the first occurrence (7.18 Ma) and last occurrence (6.32 Ma) of Reticulofenestra rotaria, calculation of linear sedimentation rates, age determination of basalt basement (~14.5 Ma), and the recognition of the "carbonate crash" paleoceanographic event at the middle/late Miocene boundary. Reworked nannofossils and lithologic changes also allow a reading of a three-episode redepositional history (4.7, 8.3, and 10.7 Ma, respectively) in the eastern Pacific. The detailed examination of the Site 1256 material also yielded well-preserved Discoaster stellulus, for which only the distal view had been depicted in the original description. In Chapter 2, a redescription and re-illustration of both sides of this asterolith is provided. This should prevent misidentification of specimens in proximal view, thereby raising its potential application for middle-late Miocene biostratigraphy. Based on the above age model, in Chapter 3 stable oxygen and carbon isotopes were used for the first time to explore the late/middle Miocene "carbonate crash". This carbonate transition is a widespread (eastern and central equatorial Pacific, Indian, South Atlantic, and the Caribbean), sharp decrease in carbonate mass-accumulation rates, which has previously been considered only a dissolution event. The positive correlation (R2 = 0.75) between d13C and CaCO3 mass accumulation rates during 5-14 Ma at ODP Site 1256 clearly demonstrates that carbonate accumulation is mainly biologically controlled. The coincidence of the carbonate crash with negative excursions in d13C and d18O values suggests a causative mechanism related to surface-water productivity, as a result of surface-water warming and reduced upwelling. Based on these observations, one could speculate that the major middle/late Miocene sea-level drop may have caused the complete closure of the Indonesian Seaway, resulting in a piling-up of surface warm water in the west Pacific. The eastward spread of this nutrient-poor water then would have warmed sea-surface temperatures and reduced upwelling in the central and eastern Pacific, thereby creating a prolonged "El Nino" scenario and reducing biological productivity of phytoplankton. The reduction in carbonate supply to the deep waters consequently caused a rapid shoaling of the carbonate compensation depth, thereby triggering the carbonate crash. The PETM was a catastrophic, rapid greenhouse-forced global warming event ~55 m.y. ago that triggered an abrupt turnover in ocean chemistry and circulation as well as biota. Chapter 4 represents a quantitative study of the response of nannoplankton to the PETM at Demerara Rise, equatorial Atlantic (Site 1259). Toweius, Fasciculithus, and Chiasmolithus sharply decrease at the onset of the PETM, whereas Chiasmolithus, Markalius cf. M. apertus, and Neochiasmolithus thrive immediately after the event, which also signals the successive first appearances of Discoaster araneus, Rhomboaster, and Tribrachiatus. Two main environmental factors were extracted by correspondence analysis of relative abundance data. The time series of the two factors shows that during the PETM, 1) environmental stress (most likely from changes in seawater pH) increased and may well have also induced the evolution of ephemeral nannofossil "excursion taxa"; and 2) surface-water productivity increased at this site presumably due to higher runoff from continental areas. The local phytoplankton opportunist, Markalius cf. M. apertus, is described as a new species in Chapter 5, which will be published under the name Coccolithus bownii. Results presented in Chapter 6 from Site 1135 on the Kerguelen Plateau, Southern Ocean suggest that nannoplankton responded differently to the PETM at southern high latitudes. The onset of the carbon isotope excursion occurs within an 18-cm interval (instead of 1-2 cm as observed in most deep-sea sections) before the peak is reached, displaying a linear mixing curve. This indicates that the release of light carbon was a gradual, single injection, instead of multiple pulses as suggested in previous work, and that this sequence is highly expanded as a result of high sedimentation rates at this relatively shallow oceanic site. This is evidenced by the high numbers of dissolution-susceptible holococcoliths (Zygrhablithus bijugatus) preserved throughout the sequence. Although r- and K-selected specialists exponentially increase in abundance at the onset, Chiasmolithus abruptly drops but then rapidly recovers, whereas Discoaster and Fasciculithus show opposite trends, indicating that in high latitudes, surface-water oligotrophy prevailed at the carbon isotope excursion (CIE) onset but mesotrophic conditions dominated the CIE recovery. These observations confirm previous results from ODP Site 690 on Maud Rise. The intensive dissolution of susceptible holococcoliths and the poor preservation of the assemblages are believed to have been caused by the effects of corrosion caused by the methane release. The different responses of nannoplankton to the PETM and the contrasts evident in previous work from the open ocean vs the continental margins further demonstrate that the response to the PETM can be influenced by local differences in geologic setting and oceanographic conditions. / A Dissertation submitted to the Department of Geological Sciences in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester, 2007. / July 13, 2007. / Paleoceanography, Paleocene/Eocene Thermal Maximum, Middle/Late Miocene Carbonate Crash, Productivity, Stable Isotopes, Calcareous Nannofossils / Includes bibliographical references. / Sherwood W. Wise, Jr., Professor Directing Dissertation; Richard L. Iverson, Outside Committee Member; Anthony J. Arnold, Committee Member; Joseph F. Donoghue, Committee Member; Yang Wang, Committee Member.

This research involves the creation of a new storm surge index that incorporates many variables important in storm surge generation like maximum winds, radius of maximum winds, pressure, translation speed, and bathymetry. Using a two-dimensional, barotropic ocean model, power laws have been developed that describe the relationship between storm surge and changes in maximum wind, radius of maximum winds, pressure, and bathymetry. Direct curve fitting is used to describe the relationship between storm surge and changes in translation speed since a power-law relationship does not exist in that case. A database of 39 landfalling, United States hurricanes between 1986 and 2007 is used to evaluate the quality of the index. Storm parameters for all database storms are compiled using the extended best track dataset, and an index value is calculated for each storm in the database. Correlation analysis is then performed using the index values and observed maximum storm surge heights. Finally, an extensive error analysis is presented to demonstrate uncertainties in the index in both forecast and post-analysis situations. / A Dissertation submitted to the Department of Meteorology in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Summer Semester, 2008. / April 23, 2008. / Hurricane, Flood, Storm Surge, Forecasting / Includes bibliographical references. / Carol Anne Clayson, Professor Directing Dissertation; Jennifer Georgen, Outside Committee Member; Robert Hart, Committee Member; Paul Ruscher, Committee Member; Peter Ray, Committee Member; Steven Cocke, Committee Member.

Climate variability is an important characteristic of regional climate, and a subject to significant control from teleconnections. An extended diagnosis of the capacity of climate models to represent remote controls of regional climate (teleconnections) is vital for assessing model-based predictions of climate variability, understanding uncertainty in climate projections and model development. An important driver of climate variability for Africa is the sea surface temperature (SST) - rainfall teleconnection, such as the El Ni˜no/Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD). In this study, an assessment of the teleconnection between tropical SSTs and Eastern African rainfall in global and regional climate models is presented, with particular attention paid to the propagation of large-scale teleconnection signals (as represented by model reanalyses and Coupled Global Climate models (CGCMs)) into the domain of the Regional Climate Models (RCMs). The teleconnection-rainfall relationship with the Eastern Africa region is assessed in two rainfall seasons (June-July-August-September and October-November- December) under present and future periods. Evaluation runs (RCMs driven by reanalysis datasets) and historical simulations (RCMs driven by CGCMs) are assessed to quantify the ability of the models to capture the teleconnection relationship. The future analysis is performed for two Representative Concentration Pathway scenarios (RCP4.5 and RCP8.5) to assess future change in this relationship as a result of global warming. Using ERA-interim reanalysis as perfect boundary conditions, the RCMs adequately simulate the spatial and temporal distribution of rainfall in comparison with observations, although the model performance varies locally and seasonally within the region. Furthermore, the RCMs correctly capture the magnitude and spatial extent regional-scale seasonal rainfall anomalies associated with large-scale oceanic modes (ENSO and IOD). When the lateral boundary conditions are provided by CGCMs, RCMs barely capture the regional teleconnection patterns associated with large-scale modes, and mostly depend on the selection of the driving CGCM. Comparison of the CGCM-driven RCM simulations with the reanalysis-driven RCM simulations revealed that most of the errors in teleconnection found in the RCM simulations are inherited from the host CGCMs. The ERA-Interim driven downscaled results show better agreement with observed spatial teleconnection patterns than the CGCM driven downscaled results. Analysis of the CGCMs and corresponding downscaled results showed that in most cases both the CGCM and the corresponding downscaled simulations had similar teleconnection patterns, but in some cases the RCM results diverge to those of the driving CGCM results. It has been demonstrated that similarities in SST-rainfall teleconnection patterns between the RCM simulations and respective driving CGCM simulations are noted over the equatorial and southern part of the region during OND season, where the rainfall is primarily controlled by large-scale (synoptic-scale) features, with the RCMs maintaining the overall regional patterns from the forcing models. Di↵erences in RCM simulations from corresponding driving simulations are noted mainly over northern part of the domain during JJAS, which is most likely related to mesoscale processes that are not resolved by CGCMs. Looking at the model projections of the future, although the spatial pattern of teleconnections between ENSO/IOD and rainfall still persist, important changes in the strength of the teleconnection have been found. During JJAS, ENSO is an important driver of rainfall variability in the northern parts of the region where dry anomalies are associated with El Ni˜no and wetter anomalies with La Ni˜na. Both regional and global ensemble projections show higher rainfall during La Ni˜na and lower rainfall during El Ni˜no over the northern part of the region compared to the present period. During OND, the teleconnection between ENSO/IOD and rainfall is projected to strengthen (weaken) over Eastern horn of Africa (southern parts of the region) compared to the present period. This implies heavy seasonal rains associated with positive phases of ENSO and IOD will increase in future across the Eastern horn of Africa. The change OND rainfall teleconnections are stronger and also more consistent between the models and scenarios as compared to the change in JJAS teleconnections. These findings have an important implication for the water and agricultural managers and policies in the region to tackle the anticipated droughts and floods associated anthropogenic climate change. Finally, the analysis demonstrated that the largest source of uncertainty in the regional climate model simulations in the context of teleconnective forcing of rainfall over Eastern Africa is the choice of CGCM used to force the RCMs, reinforcing the understanding that the use of a single GCM to downscale climate predictions/projections and using the downscaled product for assessment of climate change projections is insufficient. Simulations from multiple RCMs nested in more than one GCM, as is undertaken in the Coordinated Regional Downscaling Experiment (CORDEX), are needed to characterize the uncertainty and provide estimates of likely ranges of future regional climate changes.

Global climatic processes which control the interannual variability of summer rainfall over South Africa are studied. Monthly and seasonal rainfall variations are analysed with respect to fluctuations in sea surface temperature (SST), outgoing longwave radiation (OLR) and tropospheric winds. OLR is used as a proxy for convective intensity and for the identification of areas of sympathy and opposition to convection over South Africa. Wind data (and derived parameters) are employed to explore large- scale tropical dynamical structures. Plausible explanations are offered for the observed associations. A change in sign of the correlation structure from the October/November rainfall regime to the December through March regime is indicative of a shift from downstream advective processes (Atlantic side) to a teleconnection-type of behaviour (Indian Ocean side). Rainfall variations during the late summer months show significant (and negative) links with SST fluctuations within the equatorial/tropical Pacific and Indian Ocean areas and are consistent with results obtained in analyses with respect to OLR fluctuations. December OLR in the Western Equatorial Indian Ocean is associated with a large portion of the variance in late summer rainfall, and points to a possible relation with the evolution of the Indian monsoon. The positive association implies that reduced cloudiness off the eastern coast of equatorial Africa in the spring precedes above normal mid- and late- summer rainfall over South Africa. Vertical mass overturnings are investigated through the velocity potential and derived parameters (the Zonal Circulation and Meridional Circulation Indices). The results suggest that the vertical tropospheric cells are among the important associated components which modulate climate across southern Africa, and that broad scale flows have an impact upon regional circulation cells. Evaluation of the vertical circulations with respect to wet and dry composites reveals that the Walker-type cell which connects a branch over the Indian Ocean gradually forms after November and reaches peak development in February. A slight increase of SST in the Central Equatorial Indian Ocean (CEI) modifies the Walker cell anomaly leading to below normal summer rainfall over South Africa. Additional thermodynamic inputs in the CEI region are conducive to deeper convection, hence elevated outflow signatures are observed in the velocity potential and related fields. It is conjectured that the teleconnections between South Africa, the CEI and the remote Pacific Ocean regulate the depth of moisture influx and convergence over South Africa. Based on the results of this study, it is believed that empirical models could be designed for long-range prediction of summer rainfall anomalies over the central interior of South Africa.

The Florida manatee (Trichechus manatus latirostris) is an obligate aquatic mammal that inhabits shallow coastal waterways. Previous research has demonstrated that manatees vocalize using frequencies that range from < 0.5 kHz to 12 kHz (Frisch and Frisch, 2003; Nowacek et al., 2003) and hear frequencies between 0.4 kHz and 45 kHz (Bullock et al., 1982; Gerstein et al., 1999). Although the auditory anatomy has been described previously (Fischer, 1988; Ketten et al., 1992; Chapla and Rommel, 2003), potential sound pathways and middle ear mechanisms have not been analyzed. In the current study, Computerized Tomography (CT) is utilized to generate three-dimensional reconstructions of manatee heads and isolated earbone (tympanoperiotic) complexes in order to visualize the in situ arrangement of soft tissue and bone. Density data attached to the CT data are used to make calculations regarding the transmission and reflection of sound waves, with varying angles of incidence, as they encounter the boundaries of different tissue layers. Sound waves with 90° angles of incidence (relative to the tissue/water interface) will transmit 94% to 99% of their total energy intensity to the skull. Sound waves approaching at oblique angles to the surface of the head will transmit less of their energy intensity. The fraction of energy intensity in the transmitted wave will decrease with a decrease in the angle of incidence. Additional calculations of critical angles and an isospeed channel suggest that the inner fatty tissue layer (bounded by muscle and bone) does not provide an efficient channel for sound waves. Other potential sound pathways are discussed. A model of inertial bone conduction predicts that the peak displacement amplitude of the stapes, relative to that of the head, will be 8.4 dB at 200 Hz, and that inertial bone conduction may be possible between 125 Hz and 1000 Hz. Comparisons are made with data from humans and golden moles (Mason, 2003). / A Thesis submitted to the Department of Oceanography in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester, 2006. / April 7, 2006. / Middle Ear Anatomy, Three-Dimensional Reconstruction, Manatee Hearing, Inertial Bone Conduction / Includes bibliographical references. / Douglas P. Nowacek, Professor Directing Thesis; Sentiel A. Rommel, Outside Committee Member; Markus Huettel, Committee Member; Louis St. Laurent, Committee Member.

The purpose of this study is to test a perfect prognosis scheme used to develop lightning guidance for the warm season (May-September) for three regions of the country (Colorado, Washington, D.C., and Oregon). This guidance product is developed on a 10 × 10 km grid at 3-hourly intervals. Four seasons of RUC20 analyses and NLDN data are used to develop BLR equations for predicting one or more flashes (PROB ≥ 1), as well as predicting the amount of lightning (PROB ≥ T) for each 3-h period. RUC analyses of differing geopotential heights for each region and a map typing procedure to develop lightning frequencies for five dominant flow regimes are implemented to capture small-scale enhancements due to local forcing that are not well resolved by NWP models. Binary logistic regression (BLR) is used to develop equations for forecasting one or more flashes, while a negative binomial (NB) statistical model is used to predict the amount of lightning, conditional on one or more flashes occurring. The map-type frequencies are used as candidate predictors for both the BLR and NB models. RUC-analyzed parameters describing moisture, temperature, wind and stability also are used as candidate predictors in the PP equations. The perfect prognosis scheme is evaluated using independent data from mesoscale models during the 2009 warm season. Output from the National Centers for Environmental Prediction (NCEP) 13-km RUC (RUC13) and the NCEP 12-km North American Mesoscale Model is used to evaluate the performance of the new lightning guidance products. The goal is to beat lightning forecasts that are attained from climatology and persistence alone for each region. For most forecast periods, there is good agreement between the model forecasts and observed lightning verification. Brier score analysis indicates that our models beat climatology in forecasting one or more flashes, as well as the amount of lightning. Reliability also indicates that our models perform well for forecasting one or more flashes, but not for forecasting the amount of lightning. The goal is to make the technique a fully operational guidance product that can be used for NWS offices in these three regions. / 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, 2010. / May 18, 2010. / Statistical Studies, Lightning Forecasts / Includes bibliographical references. / Henry E. Fuelberg, Professor Directing Thesis; Philip Sura, Committee Member; Guosheng Liu, Committee Member; Andrew I. Watson, Committee Member.

There are no IAEA-GNIP stations in Florida. In order to improve our understanding of the proxy climate records preserved in speleothems, tree rings and lake sediments and to explore the utility of stable oxygen and hydrogen isotopes in the investigation of the water cycle in North Florida, there was a need to establish rainwater sampling stations to fill a gap in the oxygen and hydrogen records of rainfall in North Florida. Rain samples collected from Tallahassee and Pensacola in North Florida were analyzed for stable oxygen and hydrogen isotopic ratios. The Tallahassee samples span a time period from May 2006 to January 2011 and the Pensacola samples were collected from November 2004 to January 2010. Water samples were also collected in late 2010 and early 2011 from two coastal lakes (Eastern Lake and Western Lake in Walton County) and two ponds (Pond 1 and Bluesink in Apalachicola National Forest) in North Florida for stable isotope analyses. The δ18O and δD values of rain samples all plot either on or close to the Global Meteoric Water Line (GMWL) on a δ18O vs δD plot while most of the lake/pond water samples plot below the GMWL indicating that the lake waters in those area have been significantly affected by evaporation. Stable isotopic ratios of the Tallahassee samples ranged from -13.6 to 0.4‰ for δ18O and -99.4 to -2.2‰ for δD values (n=43) while those of the Pensacola samples ranged from -16.0 to 1.5‰ for δ18O and -115.8 to 118.9‰ for δD (n=260). Lake waters yielded δ18O values ranging from -4.7 to 1.9‰ and δD from -31.8 to 14.2‰. Pensacola samples have weighted monthly mean δ18O and δD values that ranged from -7.3 to -1.5‰ and from -4.3 to -18.7‰, respectively. The annual weighted mean δ18O and δD values for Tallahassee for study period are -4.5 and -23.3‰ respectively and -4.3 and -18.7‰ for Pensacola. The average d-excess value is 14‰ for Tallahassee and 9‰ for Pensacola. There is a negative correlation between the precipitation amount and the stable isotopic ratios of preciptation during the study period in North Florida. However, the "amount effect" can only explain less than 20% of the variance in the δ18O values of precipitation likely due to variations in the source and history of atmosphric moisture. There is a weak (but not significant) positive correlation between the average air temperature and the stable isotopic compositions of precipitation, suggesting that temperature is not a major factor in controlling the stable isotopic composition of precipitaion in this area. In Talahassee, rain samples for winter months had δ18O values ranging from -5.3 to -2.6‰, δD values from -30 to -6.2‰, and d-excess from 9.7 to 18.8. During the summer season, rain in Tallahassee displayed a larger range of isotopic variation, with δ18O and δD values ranging from -13.6 to 0.4 and from -99.4 to -7.7‰, respectively, and d-excess ranging from -11.2 to 14.7. The larger isotopic variability observed in the summer is primarily due to tropical storms. Rain samples from Pensacola had slightly more enriched monthly mean δ18O values than Tallahassee samples probably because Pensacola is located closer to the main moisture source ( the Gulf of Mexico). Tropical storms (such as Alberto and Fay) not only produced large amounts of precipitation but also are characterized by very negative δ18O and δD values. The much lower than normal δ18O and δD values of tropical storms are likely recorded in tree rings and speleothems, and thus identification of storm signals in tree rings or speleothems would allow reconstruction of paleostorm history in the area. The unique isotopic signatures of tropical storms can also serve as a tracer to study the source and flow path of groundwater. / 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, 2011. / April 1, 2011. / Isotope, Precipitation, Temperature, Amount Effect, Continental Effect / Includes bibliographical references. / Yang Wang, Professor Directing Thesis; James Tull, Committee Member; Lynn Dudley, Committee Member; Yuch-Ping Hsieh, Committee Member.

The purpose of this dissertation is to study the interannual flows along the western and southern Australian coasts and along the northern coast of the Gulf of Mexico. Along the western and southern Australian coasts, sea levels are highly correlated with the El Ni˜no signal due to the leak in the gappy western equatorial Pacific Ocean boundary. Along the western Australian coast the coastline is nearly meridional and particle displacements near the coast undergo a change in Coriolis parameter. In order to keep the potential vorticity constant, this interannual coastal signal should propagate westward as Rossby waves with large zonal scale. TOPEX/Poseidon sea level data and coastal tide gauge measurements do show these large-scale waves off Australia's northwest coast. Along Australia's nearly zonal southern coast, particle displacements are nearly zonal near the coast and experience no planetary vorticity change. Consequently the Rossby wave mechanism fails and theory suggests that the signal should decay from the shelf edge with baroclinic Rossby radius of deformation scale. High-resolution along-track TOPEX/Poseidon sea level heights show that the interannual height signal does decay rapidly seaward of the shelf edge with this scale. The sharp fall in sea level and geostrophic balance imply strong (10 cm/sec) low frequency currents seaward of the shelf edge. On the shelf, inter annual flow is in the same direction as the shelf edge flow but much weaker. The anomalous flows tend to be eastward during La Ni˜na, when the western equatorial Pacific and Australian coastal sea levels are unusually high, and westward during El Ni˜no when coastal sea levels tend to be anomalously low. The anomalous low-frequency flows can transport larvae large distances, enhancing the recruitment of Australian salmon to nursery grounds in the eastern part of the southern coast when the coastal sea level is higher than normal and decreasing recruitment when it is lower than normal. Along the shelf edge south of 23oS of the western Australian coast, although the coastline is nearly meridional, high resolution satellite sea level estimates show that the inter annual sea level signal does not have the expected large spatial scale as it decreases rapidly seaward from the shelf edge. The drop in interannual sea level amplitude coincides with the mean position of the Leeuwin Current. Theory shows that a nearly meridional mean flow, as in the case of the Leeuwin Current, can induce this fall in interannual signal amplitude by altering the potential vorticity balance. The associated interannual shelf-edge flow tends to strengthen the Leeuwin Current during La Ni˜na, weaken it during El Ni˜no and may profoundly affect the recruitment of the western rock lobster. Past work has shown that the interannual wind stress curl in the North Atlantic generates Rossby waves that reach the eastern U.S. coast and affect coastal sea levels both there and along the northern coast of the Gulf of Mexico. Tide gauge and TOPEX/Poseidon satellite sea level height measurements show that this signal penetrates all the way around the Gulf shelf to the Yucatan Peninsula, local alongshore interannual wind stress increasing the signal amplitude between Pensacola and the Texas-Louisiana shelf. In accordance with theory, satellite observations show that the seaward spatial structure of the sea levels and the associated geostrophic flows depend on the angle of the coastline with respect to due north and the Loop Current mean shelf edge flow. Off the eastern boundary (small) formed by the west coast of Florida, the Loop Current distorts the potential vorticity balance and the sea level falls rapidly from the shelf edge with a scale of order the Loop Current width. Off the northern boundary ( 90o), the signal behaves as a coastal Kelvin wave, the sea level amplitude falling quickly away from the shelf edge with first baroclinic radius of deformation scale. Off the western boundary ( 180o), the interannual sea level amplitude falls rapidly seaward of the shelf edge consistent with short western boundary scales. Geostrophic shelf edge flow may reach amplitudes of order 10cms−1 but along shelf flow amplitudes are a few cm/s or less. Even so, weak shelf flows of low frequency can transport particles many hundreds of kilometers. / A Dissertation submitted to the Department of Oceanography in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester, 2004. / October 22, 2004. / Interannual Flows, Physical-biological Interaction, Remote Sensing, Continental Shelf Dynamics / Includes bibliographical references. / Allan J. Clarke, Professor Directing Dissertation; Fei-Fei Jin, Outside Committee Member; William Dewar, Committee Member; Doron Nof, Committee Member; Richard Iverson, Committee Member.