During IODP Leg 317 off the east coast of New Zealand, three continental shelf sites (U1351, U1353 and U1354) and one continental slope site were cored. Sedimentary sequences representing shallow water depositional cycles were recovered and ranged from Upper Miocene to recent in age. One of the most widely used tools in the academic and scientific realm by onboard paleontologists to quickly determine such ages, along with foraminifera, are calcareous nannofossils. Adequate ages are highly dependent on the amount of time the shipboard paleontologist has to scan samples for biozone markers, and in some instances, zonal markers are unable to be found. Therefore, it is sometimes necessary for a secondary, post-cruise analysis of sediments to confirm the biostratigraphy developed during the cruise. Secondary objectives for this project include development of calcareous nannofossil abundance counts to analyze population dynamics, richness, evenness, and diversity as well as examination of ages and abundances of reworked and transported nannofossil assemblages in order to better understand transport mechanisms and sediment sourcing of the area. This additional onshore post-cruise analysis will allow for a more detailed study of the biozonation of the region as well as general assemblages. It is also believed that nannofossil abundances/assemblages undergo a profound change across sequence stratigraphic boundaries. This work aims to analyze these changes and determine the feasibility of using nannofossils to study these depositional cycles. Simple smear-slides have been prepared from ~100 samples and are currently undergoing semi-quantitative analysis using an Axioscope II light microscope. Shipboard biostratigraphic analysis of calcareous nannoplankton is crucial for accurate determination of stratigraphic ages due to their diversity, rapid evolution/mutation, and abundance in marine sediments. Establishing good age control allows for correlation with other proxies to develop precise chronology of cored sediments. / 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, 2013. / March 29, 2013. / Biostratigrapy, Calcareous, Canterbury, Nannofossils, Pleistocene, U1352 / Includes bibliographical references. / Sherwood W. Wise, Professor Directing Thesis; William Parker, Professor Co-Directing Thesis; Yang Wang, Professor Co-Directing Thesis.

Apalachicola Bay is a shallow estuarine system enclosed by a chain of barrier islands on the west Florida shelf. It is important both ecologically and economically due to the high biological productivity in the bay. The bay is subject to fluctuations in salinity, temperature, and dissolved oxygen. Salinity fluctuations are beneficial to many organisms in the bay. Measurements in and around the bay are analyzed to give a general description of how the bay's hydrographic properties vary in space and time. A salinity model using conservation of mass and salt is constructed in order to describe how the bay's salinity changes due to various forcing mechanisms. The main factors affecting salinity in Apalachicola Bay are freshwater inflow from Apalachicola River, winds in the direction of the major axis of the bay, and to a lesser extent, tides. When smoothed with a ten day filter, the salt model results over the three year study period agree with observations in each side of the bay at a correlation between 0.8 and 0.9. Variations in the concentration of dissolved oxygen with time are also analyzed, and the processes driving these are wind speed, temperature, biological activity, and advection. During one period when tides affect the concentration of dissolved oxygen, a regressive model based on tidal velocity and light measured near the bottom agree with observation at a correlation of > 0.8. / 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. / Summer Semester, 2013. / July 1, 2013. / Includes bibliographical references. / Kevin Speer, Professor Directing Thesis; Eric Chicken, University Representative; William Dewar, Committee Member; Mark Bourassa, Committee Member; William Landing, Committee Member.

This study presents a new algorithm to dealias folded Doppler velocities in S, C, and X-Band radars using a new boundary detection technique on the raw velocity field as a whole, rather than the traditional gate by gate methodology used in more popular and widespread algorithms. Several different types of precipitation events are used to compare and contrast the final output of the new boundary based algorithm. The results are then compared to the NEXRAD dealiasing algorithm as defined by Eilts and Smith (1989) and an objective manual unfolding by radar manipulation software called SoloII. / 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, 2013. / June 26, 2013. / Aliasing, Doppler, radar / Includes bibliographical references. / Peter Ray, Professor Directing Thesis; Henry Fuelberg, Committee Member; Guosheng Liu, Committee Member.

Integrated Ocean Drilling Program Hole 1396C, adjacent to Montserrat Island, provides a lower Pliocene to Pleistocene record of calcareous nannofossil assemblages (CN11 to CN15). The nannofossil assemblages are generally common to abundant with moderate preservation in the upper Pleistocene, and very abundant with good preservation in the lower Pleistocene and the Pliocene. The sequence was zoned via the Gartner (1977) scheme for the Pleistocene and the Okada and Bukry (1980) zonation for the Pliocene using the recent age updates from Backman et al. (2012). Sedimentation rates inferred by nannofossil biostratigraphy suggest low sedimentation rates in the Pleistocene and high sedimentation rates during the Pliocene. This sedimentation pattern was also observed at Site 1000 from Ocean Drilling Program Leg 165 in the central Caribbean Sea, suggesting a regional event caused by the closure of the Central American seaway. During the expedition (IODP, Expedition 340), selected samples from Holes 1396A and C were used to determine the sediment water content by heating them at 105°C at room pressure for 24 hours. This process produced an artificial "late diagenesis" effect with severe overgrowth features on the nannofossils. Further examination of the diagenetic progression in these samples should provide a better understanding of the progression of carbonate diagenesis in cases of high temperatures and pressures. / 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 2013. / March 27, 2013. / Calcareous nannofossils, Caribbean Sea, Diagenesis, Lesser Antilles, Pliocene-Pleistocene / Includes bibliographical references. / Sherwood W. Wise, Jr., Professor Directing Thesis; Yang Wang, Committee Member; William Parker, Committee Member.

In the uppermost millimeters of shallow marine sands, photosynthesis by microalgae can cause oxygen supersaturation, leading to formation of oxygen bubbles and subsequent ebullition of the gas from the sediment. The role of ebullition for transport and reaction mechanisms in sandy environments is poorly understood. I show that the ebullition of this gas from permeable sediments can affect the circulation and exchange of water across the sediment-water interface, thereby enhancing interfacial solute exchange. In sands, free gas occurs mostly as small inconspicuous interstitial bubbles in the surface layers that, despite their small size, can affect the physical characteristics of the sediment or surface because they are compressible and provide gas reservoirs that allow gas exchange. Over time, the gas will equilibrate with the surrounding environment, leading to a change in volume and composition. These processes may also affect the biogeochemical activities in the sediment and water column. The small bubbles in the interstitial spaces of sands can combine into bubbles in the millimeter size range with buoyancy large enough to penetrate the sediment resulting in ebullition. So far, this process of gas ebullition from permeable sand has not been investigated in detail. The main goal of this study was therefore, to assess the role of ebullition on solute flux and oxygen dynamics in the sediment. I conducted seasonal field measurements of gas ebullition and sediment free gas content, and analyzed the composition of these gases. The highest gas ebullition volumes were generally observed in the afternoon and evening hours before midnight, a pattern reflecting the build-up of oxygen in the sediment after sunrise, reaching supersaturation in the late morning hours and bubble formation thereafter. The lowest bubble volumes were measured after midnight and in the early morning. Ebullition rates reached up to a maximum 15.6 ml m-2 h-1 with a peak of 62.3 ml m-2 h 1 between the hours of 12:00-18:00 during the summer season. On a yearly average, about 59 ± 32 percent of the gas that was measured from the bay was released from the sediment. There is a noticeable offset between bubble formation in the sediment to maximum rates of gas release. The latter became most significant and exceeded the sedimentary gas volumes mainly during the afternoon hours. The maximum volume of gas was recorded in August at 492.4 ml m-2 d-1, which integrates gas volume released from the sediment and the free gas still present in the sediment. Assuming photosynthetic activity by microalgae only occurs down to a sediment depth of 0.5 cm, this gas volume theoretically equates to approximately 10% of the total sediment volume affected by gas bubble formation. In this study, most of the measured gas was not collected in the sediment, but rather in the overlying water column. The maximum volume of gas that a given volume of sediment can contain before ebullition occurs, at 1 cm sediment depth, was determined to be around 0.064 ± 0.005 ml in the lab. In the natural environment, this maximum volume would also largely depend on a variety of physical, chemical and biological factors. In order to assess the effect of ebullition on sediment-water solute exchange, I conducted laboratory experiments utilizing sediment columns with pore water that contained inert fluorescein dye. Bubbles released at six different depths in the sediment resulted in a 4 to 21 fold enhancement of sediment-water solute flux relative to diffusion-only transport. The strongest increase of dye flux from the pore water into the overlying water was recorded when bubbles were released closest to the sediment-water interface, where individual gas bubbles were the smallest in volume but the release rate of individual bubbles was the highest. Subsequent analyses of larger sediment cores (57 cm diameter, ~ 5 cm in height) revealed a distinct pattern of dye washout caused by the ebullition that extended below the level at which the gas was released at 2.5 cm depth. This result demonstrated the effectiveness of pore water circulation caused by bubble release for the vertical and horizontal mixing of pore fluids, particularly near the origin of ebullition. With a transfer of the laboratory experimental design to the field using 19-cm diameter chambers with rotating discs and chamber water spiked with inert bromide (Br-) tracer, we could show that the average volume of pore water exchange in five different ebullition chambers was 231 ± 96 L m-2 d-1. Compared to the average from four non-ebullition chambers (79 ± 96 L m-2 d-1), the difference in interfacial tracer flux caused by ebullition was almost 3-fold. Investigations were also undertaken on oxygen gas bubble behavior in both the field and laboratory. Correlation comparisons between the collected gas samples from St. Joseph Bay and the measured environmental factors show that the change in the gas volume is most closely associated with sunlight, albeit with a lag time. While the rate of increase in the oxygen concentration was the greatest at the onset of the day (6:00-12:00), the volume maxima was not typically reached until the afternoon hours. The average concentration of oxygen in the bubbles during the summer at the bay exceeded 50% in both the sediment and bubble trap samples. The flux of oxygen from the sediment through ebullition was up to 5.93 ± 0.63 mmol m-2 d-1 during August. Pure oxygen gas was released at the sediment-water interface, as well as 2 cm in the sediment and collected at 20-cm intervals up to 1 m to see if any immediate changes in composition would occur. The gas stripping was further pursued in the lab by injected known volumes of pure oxygen (5, 10 or 15 ml) into seawater control vials and (5 or 10 ml) into glass containers filled with fresh, wet sediment collected from the bay. The loss of oxygen in the rising bubbles in the water column at St. Joseph Bay was 21% greater when gas was injected at 2 cm in the sediment versus at the sediment surface. In the lab experiments the gas samples in the sediment loss 43 and 33 percent more oxygen following 24 hours, with rates of decrease approximately 4.9 and 5.5 times (5 and 10 ml experiments) higher than the controls. In all experiments, the sediment demonstrated higher rates of oxygen consumption than in the water column, and N2 was the only other gas found in all of our gas samples. / 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, 2013. / October 19, 2012. / Includes bibliographical references. / Markus Huettel, Professor Directing Thesis; Ian MacDonald, Committee Member; Joel Kostka, Committee Member; Jeffrey Chanton, Committee Member.

Extreme events are phenomena which occupy the tail-end of a distributions PDF. While atmospheric phenomena are decidedly non-Gaussian, the exact shape of these tails of a distribution are relatively unknown. From stochastic theory, it is noted that tails or extremes may be predicted by the behavior of power-law distribution. While prior research for the empirical search for power-laws has been heavily qualitative in nature, this study aims at the quantitative and statistical fitting and analysis of power-laws across the southeastern United States with respect to daily maximum and minimum temperatures. Utilizing a power-law fitting algorithm, we may fit power-law distributions to the PDFs of atmospheric maximum and minimum temperatures. After statistical analysis, we may note the universal significance of these power-law tails throughout the southeastern United States within regions of non-Gaussianity. Further, we analyze varying behavior of these significant power-laws within the distribution's PDF. From this, we may note and observe the behavior of these extremes events in relation to weather and climatic cycles. / 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, 2013. / May 30, 2013. / Includes bibliographical references. / Philip Sura, Professor Directing Thesis; Zhaohua Wu, Committee Member; Mark Bourassa, Committee Member; Lydia Stefanova, Committee Member.

The cardinal role of the atmosphere in the global dispersion of mercury and its deposition in aquatic environments and on land is well established. Re-emission of mercury from waters and land is the major source of atmospheric mercury. If isotopic variations in Hg are to be used in developing a better understanding of the mercury cycle, experimental studies of the isotopic effects of those processes that induce mercury transformations from one species to another and its transition in and out of the atmosphere are critical. Knowledge of the isotopic composition of atmospheric mercury is also a key. This study has attempted to determine the isotopic signature of Hg in the atmosphere to provide an anchor for geochemical models of mercury. The residence time of Hg0 which comprises of approximately 98% of the total mercury in the atmosphere has been variously estimated to be between 0.6 and 2.0 years. Both the horizontal and vertical mixing times of the troposphere are approximately one month (vertical mixing can be much faster). Accordingly, we suspect that atmospheric mercury might closely approach isotopic homogeneity on a hemispherical scale (mixing times between the northern and southern hemispheres might well exceed a year). We have analyzed atmospheric mercury collected in our local area along the Gulf of Mexico coast at various times, elsewhere in the U.S. and at NOAA Global Baseline Observatories. Mercury is trapped on gold plated sand in a quartz tube. Air is passed through this gold trap by a pump, and a flow meter is used to monitor the flow rate. A desiccant (CaSO4) is used to absorb the moisture from the air and does not interfere with the Hg collection. To ensure that anthropogenic input was at it its minimum, sampling was not conducted in industrialized areas, or near coal powered plants and remote locations were preferred. Once the sampling is complete, mercury is thermally purged from the gold trap, and carried by a helium stream into concentrated nitric acid containing chloride, where it is completely oxidized to Hg (II). Hg (II) is reduced in a CETAC HGX 200 Cold vapor generator, and the evolving cold mercury vapor is analyzed in a NEPTUNE MC-ICP-MS. To minimize the effects of instrumental fractionation, isotope ratios were determined by sample standard bracketing technique and reported in and #61540; (') notation relative to NIST SRM 3133. Where as and #61540;AHg = ', where R= . Samples of atmospheric mercury exhibit a mass dependent fractionation effect with light isotope enrichment in 198Hg/200Hg ratios (relative to NIST-SRM 3133) of the order of 1.3 0.8 ' (2 and #963;), and small but reproducible mass independent fractionation effects with positive 199Hg and 201Hg anomalies of +0.1 to +0.3 '. From this study it is concluded that the atmosphere comes close to an isotopically uniform reservoir of mercury (IUR)Hg, on which local and temporary effects are likely imposed. This (IUR)Hg provides an anchor around which models of the global mercury cycle could be constrained. In atmospheric waters and precipitation, mercury is present in the form Hg (II). Rainwater was collected in Tallahassee, FL for isotopic analysis of mercury. Due to low concentration of mercury in rainwater, samples were pre-concentrated by adding chloride and subsequent evaporation. All samples analyzed show a small positive odd isotope anomaly of the order of 0.213 +/- 0.28 (2 and #963;) ' for 199Hg and 0.18 +/- 0.24 (2 and #963;) ' for 201Hg. A network of Tillandsia usneoides (common name: Spanish Moss), an epiphyte, was collected along the eastern Coastal Plain of the U.S. from northern Florida to North Carolina and analyzed for its isotopic composition to determine its effectiveness as a natural monitor of isotopic composition of the atmosphere in which it grows. The Spanish moss exhibits a clear negative mass independent isotope effect which is distinct from the isotopic composition of the Hg-vapor in the ambient air and Hg (II) in the rain measured. Moreover all samples plot within analytical uncertainty of the theoretical fractionation line for magnetic isotope effect with a and #916;201Hg/ and #916;199Hg ratio of 1:1.1. This clearly indicates towards a biological origin of the isotope effect seen in the moss. / A Dissertation submitted to the Department of Earth, Ocean, and Atmospheric Science in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Summer Semester, 2010. / April 27, 2010. / Includes bibliographical references. / A. Leroy Odom, Professor Directing Dissertation; William Landing, University Representative; Yang Wang, Committee Member; Stephen Kish, Committee Member.

Seamounts are largely unexplored undersea mountains rising abruptly from the ocean floor. These unique habitats can support an increased abundance and diversity of organisms, due to increased flow rates, the presence of hard substrates, and potentially, hydrographic larval retention mechanisms. Oceanic islands, sharing geomorphic characteristics, are a subset of seamounts. Suspension feeders, such as deep-sea corals, are common benthic megafauna in these ecosystems. Deep-sea corals are associated with higher levels of diversity and are structure-formers, able to provide habitat and complexity to other organisms. However, most past work addressing deep- sea coral communities in general, on seamounts in particular, have not considered small-scale variation in these communities. Here I show that the subphotic structure- forming megabenthos of an oceanic island is structured along physical gradients at a much smaller scale than previously known. Corals and sponges in the Makapu and #700;u deep- sea coral bed (4.3 km2), offshore of Oahu, Hawaii, were mapped from ~ 320 ' 530 meters depth. The physical environment was surveyed at three spatial scales in order to increase the state of knowledge regarding community-level patterns of these ecosystems and to test the hypothesis of differing communities in the northern and southern regions of the bed. This hypothesis was shown to be partially true, with communities in one region differing from those occupying the other, even within the same depth zone. Local hydrological changes are likely manifesting in regional differentiation. Depth was found to be the strongest structuring gradient. Furthermore, different relief and substrate types hosted unique assemblages, with rugosity acting as an important factor as well. Preliminary analyses of a local crinoid population provided no evidence of nocturnal behavior, as was suspected, but revealed a potential increase in crinoid abundance over time. This work yields new insight on the spatial ecology of seamounts and points out that community changes can occur over narrow (~ 200 meters) depth gradients and be structured by small-scale physiography. Future ecological investigations on seamounts would benefit from collecting faunal and physical habitat data at multiple spatial scales. / 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. / June 13, 2011. / Includes bibliographical references. / Amy Baco-Taylor, Professor Directing Thesis; Ian MacDonald, Committee Member; Kevin Speer, Committee Member.

MicroWave Humidity Sounder (MWHS) onboard both FY-3A and FY-3B satellites have three channels (channels 3-5) near 183 GHz water vapor absorption line. These channel frequencies are also used in other instruments such as Advanced Microwave Sounding Unit-B (AMSU-B) and Microwave Humidity Sounder (MHS) onboard MetOp and NOAA satellites. Both MWHS and MHS are cross-track scanners. In this study a comparison between the simulated brightness temperatures with MWHS measurements clearly shows that MWHS observations from the three sounding channels contain a scan angle dependent cohesive noise along the instrument scanline. This noise does not cancel out when a large amount of data over a sufficiently long period of time is averaged, which eliminates the possibility of such a noise to arise from natural variability of the atmosphere and the surface. The noises are around 0.3, 0.2, and 0.2 K for channels 3-5, respectively. A principle component analysis is used for the characterization of this cohesive noise using one-month FY-3B MWHS data. It is shown that the MWHS cohesive noise is contained primarily in the first PC mode, which mainly describes a scan angle dependent brightness temperature variation, i.e., a unique feature of cross-tracking instrument. The 1st PC accounts for more than 99.91% total variance in the three MWHS sounding channels. A five-point smoother is then applied to the first PC, which effectively removes such a data noise in MWHS data. The reconstruction of the MWHS radiance spectra using the noise-filtered first PC component is of good quality. The scan angle dependent bias from reconstructed MWHS data becomes more uniform and is consistent with NOAA-18 MHS data. / A Thesis submitted to the Department of Earth, Oceanic and Atmospheric Sciences in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester, 2013. / June 26, 2012. / FY-3B, MWHS / Includes bibliographical references. / Xiaolei Zou, Professor Directing Thesis; Guosheng Liu, Committee Member; Peter S. Ray, Committee Member.

This study presents a new method for assimilating lightning data into numerical models that is suitable for cloud-resolving scales (e.g., 3 km). The study utilized data from the Earth Networks Total Lightning Network at 9 km grid spacing to mimic the resolution of the Geostationary Lightning Mapper (GLM) that will be on the upcoming GOES-R satellites. The assimilation procedure was developed using the Weather Research and Forecasting (WRF) numerical model. The method (denoted MU) warms the most unstable low levels of the atmosphere at locations where lightning was observed but deep convection was not simulated based on the absence of graupel. Simulation results utilizing the new method are compared with a control simulation and a simulation employing the lightning assimilation method (FO) developed by Alexandre Fierro and colleagues. Unlike MU, the FO method increases relative humidity according to a nudging function dependent on the intensity of observed lightning and simulated graupel mixing ratio. Simulations are performed across the Central and Eastern United States for three separate severe storm cases during 2011. These cases exhibit a wide range of weather patterns and thunderstorm organization. When comparing simulation results with hourly NCEP stage IV radar and gauge precipitation observations, both the MU and FO assimilation methods produce an improved simulated precipitation field during the assimilation period and a short time afterwards based on subjective comparison and objective statistical scores. The assimilation methods commonly improve equitable threat scores by more than 0.1 and 50% during the assimilation period. Differing degrees of improvement from the assimilation methods depend on the weather pattern, with the MU method generally performing better in the simulation of isolated thunderstorms and other weakly forced deep convection. Biases in the precipitation, moisture, and temperature fields of the simulations also are examined and sometimes differ considerably between assimilation schemes. Based on performance and bias, the newly developed MU method is shown to be a viable alternative to the FO method, exhibiting utility in producing and locating thunderstorms where observed and providing a better analysis at low computational cost. / A Thesis submitted to the Department of Earth, Atmospheric, and Ocean Sciences in partial fulfillment of the requirements for the degree of Master of Science. / Summer Semester, 2013. / May 28, 2013. / Includes bibliographical references. / Henry Fuelberg, Professor Directing Thesis; Jon Ahlquist, Committee Member; Robert Hart, Committee Member.