Ocean transport of heat is a substantial component of the climate system but its characteristics and dynamic causes are still somewhat unknown. Prior research has shown that global observations from the ocean and atmosphere indicate that the ocean and atmosphere transport about 6 PW of energy from the equatorial regions towards the poles. Studies have shown that approximately 2 PW of that transport are carried by the ocean. It has been proposed that global tropical cyclone activity could account for a large amount of the mixing needed to explain the thermohaline circulation driving this transport. However, there remain insufficient observations to conclusively prove this hypothesis. After a tropical cyclone moves across the ocean it leaves behind a wake of colder temperatures in the upper ocean. The cold wake is primarily caused by mixing, upwelling and an enthalpy flux into the atmosphere. This study makes use of the JASON-1, and TOPEX/POSEIDON satellite altimeters to investigate the amount of heating of the ocean required to re-stratify the ocean to pre storm conditions. Argo floats are also used to validate results found from the sea surface height anomalies from satellite. In order to attain the necessary spatial and temporal resolution, the Climate System Forecast Reanalysis (CFSR) model is used. Given that CFSR is a coupled atmospheric and ocean model, it enabled this study to compare the modeled storms and then the impact of storms on the ocean. After the storm passed through the area, surface heating fluxes could be determined over the duration of the storm thus providing a direct comparison of heat loss and net heat gain over the entire duration of the storm. It was found that during the time period of the cold wake, the surface heating imbalance was high enough to account for all of the rewarming of the cold wake. Therefore it is possible that global cyclone activity could account for the large amount of mixing required to explain the thermohaline circulation. / 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. / Degree Awarded: Spring Semester, 2011. / Date of Defense: April 30, 2011. / Cold Wake, Argos Floats, Sea Surface Height Anomaly, Ocean Restratification / Includes bibliographical references. / Carol Anne Clayson, Professor Directing Thesis; Robert Hart, Committee Member; Paul Ruscher, Committee Member.

The HRD Real-time Hurricane Wind Analysis System (H*Wind) is a software application used by NOAA's Hurricane Research Division to create a gridded tropical cyclone wind analysis based on a wide range of observations. One application of H*Wind fields is calibration of scatterometers for high wind speed environments. Unfortunately, the accuracy of the H*Wind product has not been studied extensively, and therefore the accuracy of scatterometer calibrations in these environments is also unknown. This investigation seeks to determine the uncertainty in the H*Wind product and estimate the contributions of several potential error sources. These error sources include random observation errors, relative bias between different data types, temporal drift resulting from combining non-simultaneous measurements, and smoothing and interpolation errors in the H*Wind software. The effects of relative bias between different data types and random observation errors are determined by performing statistical calculations on the observed wind speeds. We show that in the absence of large biases, the total contribution of all error sources results in an uncertainty of approximately 7% near the storm center, which increases to nearly 15% near the tropical storm force wind radius. The H*Wind analysis algorithm is found to introduce a positive bias to the wind speeds near the storm center, where the analyzed wind speeds are enhanced to match the highest observations. In addition, spectral analyses are performed to ensure that the filter wavelength of the final analysis product matches user specifications. With increased knowledge of these error sources and their effects, researchers will have a better understanding of the uncertainty in the H*Wind product, and can then judge the suitability of H*Wind for various research applications / 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. / Degree Awarded: Fall Semester, 2010. / Date of Defense: October 8, 2010. / Hurricane, Tropical Cyclones, Wind Analysis, Uncertainty / Includes bibliographical references. / Mark Bourassa, Professor Directing Thesis; Mark Powell, Committee Member; Robert Hart, Committee Member; Guosheng Liu, Committee Member.

High-resolution Holocene sediment cores from the continental shelf of Antarctica are integral to the study of recent climate transitions, but such records are rare. The inaugural SHALDRIL I cruise to Maxwell Bay along the Northern Antarctica Peninsula, however, recovered the most expanded record to date at Site NBP05-02-1B. More than twice as long as any other such Antarctic sequence, the 108.2 m section dates back 13,480 yr B.P. Presented here is a record of climate variation interpreted from analyses of the diatom content. Diatoms have proven to be a useful tool in the study of paleoclimate. Analyses completed here include species diversity, total diatom abundance (valves per gram of sediment), Eucampia antarctica var. antarctica to E. antarctica var. recta ratio, Eucampia index, Chaetoceros resting-spore percent, Chaetoceros hyalochaete to C. vegetative ratio, and Thalassiosira antarctica T2 percentage. The analyses show a continuous sea-ice assemblage with minor fluctuations in response to changing sea-ice conditions. Other than the Thalassiosira antarctica T2 percentage, all analyses show a prominent warming period identified as the Mid-Holocene Climatic Optimum. Thalassiosira antarctica T2 percentage marks a period of deglaciation at approximately 11 ka. This episode of deglaciation has been documented in other studies and is believed to mark the onset of present-day ice conditions. / A Thesis submitted to the Department of Geology in partial fulfillment of the requirements for the degree of Master of Science. / Degree Awarded: Spring Semester, 2008. / Date of Defense: December 6, 2007. / Diatoms, Holocene, Antarctica / Includes bibliographical references. / Sherwood W. Wise, Professor Directing Thesis; Jennifer Georgen, Committee Member; Joseph F. Donoghue, Committee Member.

Geophysical data collected in 1975 and 1976 reveal major crustal and tectonic elements of the continental margin of southern Baja California. Gravity, magnetic, seismic reflection and bathymetric data show seaward extension of the islands enclosing Magdalena and Almejas Bays. A seismic reflection profile, oriented approximately normal to the trend of the Baja peninsula, indicates normal faulting of the near surface sediment layers along the outer continental shelf. The reflection record also shows that sediment layers immediately above the acoustic basement dip toward the east at the base of the continental slope. A crustal and subcrustal cross section, oriented approximately parallel to the reflection profile and constrained by gravity, magnetic, bathymetric and seismic refraction data, indicates a maximum crustal thickness of approximately 21 km for Baja California, making it intermediate in thickness between normal continental and normal oceanic crusts. The section also indicates a low density zone in the mantle below the Gulf of California. Magnetic anomalies along the cross section require oceanic crust of the Pacific Plate to extend at least 50 km landward of the edge of the western continental shelf of Baja California. This suggests either a past period of oblique subduction of the Pacific Plate beneath Baja California or emplacement of Pacific Plate oceanic crust beneath the peninsula by descending spreading centers of the East Pacific Rise. / Graduation date: 1977

Seismic refraction, reflection and gravity data obtained across the Peru continental margin and Nazca Plate at 9° S. permit a detailed determination of crustal structure. Complex structures normal to the profile require the development of a ray trace technique to analyze first and later arrivals for eleven overlapping refraction lines. Other data integrated into the seismic model include velocities and depths from well data, near surf ac sediment structures from reflection profiles and velocities obtained from nearby common depth point reflection lines. Crustal and subcrustal densities and structures were further constrained by gravity modeling to produce a detailed physical model of a convergent margin. The western portion of the continental shelf basement consists of a faulted outer continental shelf high of Paleozoic or older rocks. It is divided into a deeper western section of velocity 5.0 km/sec and a shallower, denser eastern section of velocity 5.65 to 5.9 km/sec. The combined structure forms a basin of depth 2.5 to 3.0 km which contains Tertiary sediments of velocity 1.6 to 3.0 km/sec. In this area, near-surface sedimentary structure suggests truncated sinusoidal features caused by exposure to onshore-offshore bottom currents. The 3 km thick, 4.55 to 5.15 km/sec basement of the eastern shelf shoals shoreward. Together, this basement and the eastern section of the outer continental shelf high form a synclinal basin overlain by Tertiary sediments which have a maximum thickness of 1.8 km and a velocity range of 1.7 to 2.55 km/sec. The gravity model shows a large block of 3.0 g/cm³ lower crustal material emplaced within the upper crustal region beneath the eastern portion of the continental shelf. Refraction data indicates a continental slope basement of velocity 5.0 km/sec overlying a slope core material with n interface velocity of 5.6 km/sec. The sedimentary layers of the slope consist of an uppermost layer of slumped sediment with an assumed velocity of 1.7 to 2 km/ sec which overlies an acoustic basement of 2.25 to 3.6 km/ sec. The high velocities (and densities) of the slope basement suggest the presence of oceanic crustal material over lain by indurated oceanic and continental sediments. This slope melange may have formed during the initiation of subduction from imbricate thrusting of upper layers of oceanic crust. Once created, the melange forms a trap and forces the subduction of most of the sediments that enter the trench. A ridge-like structure within the trench advances the seismic arrival times of deeper refractions and supports the suggestion that it is thrust-faulted oceanic crust which has been uplifted relative to the trench floor. The model of the descending Nazca Plate consists of a 4 km thick upper layer of velocity 5.55 km/sec and a thinner (2.5 km) but faster 7.5 km/sec lower layer which overlies a Moho of velocity 8.2 km/sec. The gravity model indicates that the plate has a dip of 5° beneath the continental slope and shelf. West of the trench, the lower crustal layers shallow, which may represent upward flexure of the oceanic plate due to compressive forces resulting from the subduction process. The upper crustal layers of the 120 km long oceanic plate portion consist of a thin 1.7 km/sec sedimentary layer overlying a 5.0 to 5.2 km/sec upper layer. An underlying 5.6 to 5.7 km/sec lower layer becomes more shallow to the east within 60 km of the trench while a deeper 6.0 to 6.3 km/sec layer thickens to the east. The lower crustal model consists of a 7.4 to 7.5 km/sec high velocity layer which varies in thickness from 2.5 km to 4.0 km. The 8.2 km/sec Moho interface varies not more than ±0.5 km from a modeled depth of 10.5 km. / Graduation date: 1979 / Best scan available for figures.

A brief tilt and strain survey was conducted in the Krafla-Namafjall area in the North of Iceland during August of 1979 in order to study the feasibility of applying solid earth tidal observations in the exploration of volcanic geothermal systems. The rationale of the survey was based on the expectation that various types of geological structures such as rift zones and magma chambers can lead to observable distortions of the local solid earth tidal amplitude field. The field procedure consisted in measuring the local tidal amplitudes and comparing them with normal theoretical amplitudes at the same location. The Krafla volcanic complex is a central volcano traversed by a N-S trending fissure swarm, that has been tectonically and volcanically active since December 1975. Accompanying this activity have been periodic inflations of the Krafla caldera, presumably caused by a flow of magma into a local magma chamber and resulting in long term tilts of the order 0.5 ��rad/day that have been observed at two sites south and southeast of the caldera. In computing theoretical amplitudes the effects of the ocean tides need to be estimated. In the case of north Iceland they are found to be of the same magnitude as the solid earth tides. The amplitudes of the M��� ocean loading tilt at Krafla are estimated to be 0.066 ��rad and 0.032 ��rad for the NS and EW components respectively. The most noteworthy result was obtained at a site in the Namafjall geothermal area inside the active Krafla fissure swarm. The ratios of the observed to the theoretical M��� tidal tilt amplitudes at this site as estimated by a least squares spectral analysis method are found to be 0.9 �� 0.3 and 3.2 �� 1.5 for the NS and EW components respectively. On the basis of some simple order-of-magnitude estimates we can exclude one of the numerous nearby fractures as a possible cause for the EW tilt anomaly and conclude that it is most likely to be generated by a large body of magma below the Krafla fissure swarm. Due to thermoelastic noise other tilt data obtained during this survey turned out to be less reliable. However, our work at a site east of the fissure swarm and southeast of the caldera indicated a possible anomaly. The strain data are highly contaminated by thermal noise and could not be successfully analyzed. These results tend to confirm that tidal tilt observations can be of use in explorations of volcanic and geothermal systems. Our work indicates that a few improvements of the simple field techniques adapted may enhance the quality of data. These include (1) increasing the instrument resolution, (2) selecting sites with surface layers that are incapable of transmitting thermal stresses and (3) obtaining more extensive higher quality temperature recordings, that should enable the thermal noise to be largely removed. / Graduation date: 1981

The purpose of this research was to quantify forest disturbance processes and evaluate the influence of these processes on secondary hardwood forest communities on a section of the Cumberland Plateau in Tennessee. The specific objectives of this study were to: (1) reconstruct the disturbance history of a secondary hardwood forest using species composition, stand structure, tree-ring data, and soil charcoal analyses, (2) quantify canopy gap formation mechanisms, (3) document canopy gap characteristics, and (4) determine the forest response to small-scale disturbance events. This information is useful to understand the importance of localized disturbances on stand development and forest successional patterns. With the exception of one stand-wide disturbance in the early 1980s, the disturbance regime of the forest was characterized by localized, asynchronous events that occurred at variable spatial and temporal scales. Gap-scale disturbance events became frequent after about 40 years of forest development. The presence of soil charcoal indicated that fire had occurred in the Pogue Creek Natural Area in the past, but species composition and a lack of fire-scarred trees indicated that fire had not occurred during the development of the current stand. The majority of canopy gaps were caused by treefall (either windthrow or basal-shear) and half of all gaps were caused by the death of a Quercus individual. Gap ages ranged from 1 to 17 years with a mean of 7 years. Seasonality of death could be accurately determined for 17 gap makers and all but one of these trees died during the growing season. Strong wind associated with convective storms is the most probable disturbance agent in the forest. The fraction of land area in expanded gaps and true canopy gaps was 15% and 6%, respectively. The amount of land area in canopy gaps was highest for younger gaps and generally decreased with increased gap age. Most expanded and true canopy gaps had elliptical shapes and the majority of gaps were oriented perpendicular to slope contours. Significant positive relationships were documented between expanded gap size and the density of saplings, trees, and total stems. Only weak relationships existed between stem diversity and expanded gap size. Most of the canopy gaps documented were projected to close by lateral crown expansion rather than height growth of subcanopy individuals, but gaps still provided a means for understory trees to recruit to larger size classes. Over half of all trees located in true canopy gaps with intermediate crown classifications were Acer saccharum, A. rubrum, or Liriodendron tulipifera. Because the gaps documented were relatively small and close by lateral branch growth of perimeter trees, the most shade-tolerant A. saccharum has the greatest probability of becoming dominant in the canopy under the current disturbance regime. This study indicated that gap-scale disturbance processes have an influence on stand development and successional patterns of secondary hardwood forests in the absence of large-scale events.

The genus Phytophthora includes more than 90 described species infecting over 1000 plant species. Population studies were conducted to investigate the survival and spread of P. capsici in the Peruvian coastal region. A total of 227 P. capsici isolates, recovered at widely distant localities from 2005-2007, were fingerprinted with AFLPs and SNP genotyping. A clonal population (PcPE-1) represented by 221 isolates was found to be distributed throughout the country. Atypical isolates of P. nicotianae were isolated from loquat trees in Peru and nuclear (internal transcribed spacer [ITS], the phenol acid carboxylase gene, and AFLPs) and mitochondrial genotyping (cytochrome oxidase gene [coxI]) identified this species as a hybrid between P. nicotianae and P. cactorum A comparison of five Phytophthora hybrid isolates from Peru and Taiwan (also infecting loquat trees) suggested that isolates from Peru likely originated from a single hybridization event and that the two isolates from Taiwan originated through different hybridization events. The generation of genetic resources for the study of complex genetic traits in P. capsici was initiated by studying its inbreeding up to the sixth generation. A total of 692 oospore-derived isolates were fingerprinted and a subset was characterized for pathogenicity in cucumber and jalapeno fruits and for segregation of the mating type. The traits tested revealed no-Mendelian segregation, and apomixis were observed to be more prevalent (100%) in deep (fifth generation) inbreeding crosses. Inbreeding was measured by studying the segregation of 20 AFLP markers, which indicated a loss of heterozygosity of ~75% by the sixth generation. The seminal cross from this study was used as a mapping population (F1) for generating a genetic linkage framework with 189 AFLP and 18 SNP markers. A total of 18 linkage groups were produced for each parental isolate using 65 and 42 markers for CBS121657 and CBS121656 isolates respectively covering 409 cM. SNP markers FL5 and FL6 were used for estimating the genome size of P. capsici and precision of the genome assembly. In order to conduct functional studies in P. capsici, we tested the efficacy of the polyethylene glycol mediated transformation. We regenerated up to 30 antibiotic resistant isolates and 53% of them were stable after three months of subculturing.

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