Tropical cyclones (TCs) are destructive, natural occurring phenomena that can cause the loss of lives, extensive structural damage, and negative economic impacts. A major hazard associated with these tropical systems is rainfall, which can result in flood conditions, contributing to the death and destruction. The role rainfall plays in the severity of the TC aftermath emphasizes the importance for models to produce reliable precipitation forecasts. Hurricane model precipitation forecasts can be improved through precipitation verification as the model weaknesses are identified. In this study, the Hurricane Analysis and Forecast System (HAFS), an experimental NOAA hurricane model, is evaluated for its skillfulness in forecasting TC precipitation. An object-based verification method is used as it is demonstrated to more accurately represent the model skill compared to traditional point-based verification methods. A 600 km search radius is implemented to capture the TC rainfall and the objects are defined by 2, 5, and 10 mm/hr rain rate thresholds. The 2 mm/hr threshold is chosen to predominantly represent stratiform precipitation, and the 5 and 10 mm/hr thresholds are used as approximate thresholds between stratiform and convective precipitation. Shape metrics such as area, closure, dispersion, and fragmentation, are calculated for the forecast and observed objects and compared using a Mann Whitney U test. The evaluation showed that model precipitation characteristics were consistent with storms that are too intense due to forecast precipitation being too central and enclosed around the TC center at the 2 mm/hr threshold, and too cohesive at the 10 mm/hr threshold. Changes in the model skill with lead time were also investigated. The model spin-up negatively impacted the model skill up to six hours at the 2 mm/hr threshold and up to three hours at the 5 mm/hr threshold, and the skill was not affected by the spin-up at the 10 mm/hr threshold. This indicates that the model took longer to realistically depict stratiform precipitation compared to convective precipitation. The model skill also worsened after 48 hours at the 2 and 10 mm/hr thresholds when the precipitation tended to be too cohesive. Future work will apply the object-based verification method to evaluate the TC precipitation forecasts of the Basin-Scale Hurricane Weather Research and Forecasting (HWRF-B) model. / Master of Science / Tropical cyclone (TC) precipitation can impose serious threats, such as flood conditions, which can result in death and severe damage. Due to these negative consequences associated with TC rainfall, it is important for affected populations to be sufficiently prepared once these TCs make landfall. Hurricane models play a large role in the preparations that are made as they predict the location and intensity of TC rainfall, which influences the peoples' choices in taking precautionary measures. Therefore, hurricane models need to be accurate, and comparing the forecast precipitation to the observed precipitation allows for areas in which the model performs poorly to be identified. Model developers can then be informed of the areas that need to be improved. In this study, the precipitation forecasts from the Hurricane Analysis and Forecast System (HAFS) model, a hurricane model that is currently under development, are evaluated. The shape and size of the forecast and observed precipitation are quantified for light, moderate, and heavy precipitation using metrics such as area, perimeter, and elongation. The values of these metrics for the forecast and observed precipitation are compared using a statistical test. The results show that the hurricane model tended to forecast storms that are too weak due to forecast precipitation being too close to the TC center, too wrapped around the TC center, and too connected. The hurricane model is also evaluated for the accuracy of its forecasts with time from model initialization. The model had a harder time representing lighter precipitation than heavier precipitation during the first 6 hours after initialization. A decrease in the accuracy of the model forecasts was also shown 48 hours after initialization due to the general degradation of model accuracy with time after initialization. Future work will evaluate the TC precipitation forecasts of another hurricane model, the Basin-Scale Hurricane Weather Research and Forecasting (HWRF-B) model.

Evolutionary periods of precipitation distribution in tropical cyclones (TCs) are sometimes misrepresented in numerical weather prediction models due to the rapid nature of TC structure changes that accompany intensity change. To better understand quantitative changes in TC rainband structure around landfall, I quantify the spatial distribution of precipitation in 62 landfalling TCs along the Gulf of Mexico and Atlantic coasts of the U.S. between 1998 and 2014. The Tropical Rainfall Measuring Mission (TRMM) 3B42 product is utilized to assess three spatial measures of precipitation: 1) area, 2) closure, and 3) dispersion. Calculations are made using two rain rate thresholds, 0.254mm/hr and 5mm/hr, to capture and compare changes in light and heavy precipitation, respectively. Changes in TC precipitation are statistically different based on landfall location along the Atlantic vs. Gulf. Overall, dispersion (measure of centrality) is the most dissimilar metric due to variability between 0.254mm/hr and 5mm/hr results. Lighter precipitation decreases in area and expands away from the TC center, while heavier precipitation contracts rather than disperses in Gulf landfalling storms. A k-means clustering produces six landfall regions and reinforces the result of heavier precipitation becoming more central along the Gulf, while Atlantic landfalling storms exhibit decreased centrality. Significant differences were not found in storms that undergo extratropical transition or dissipate later in lifecycle. The holistic approach exhibited by this study reveals wide variability among a large dataset of storms making landfall; therefore, sub-setting techniques are helpful to hurricane forecasters in understanding the role of landfall location. / MS / As our coastal communities become progressively vulnerable due to increased urbanization and settlement along United States coastlines, natural disasters, such as flooding caused by hurricanes and nor’easters, will continue to cripple coastal populations. Strong winds, storm surge, and heavy rains upon landfall during tropical cyclones produce billions of dollars’ worth of damage to infrastructure and natural resources. By understanding structural changes of hurricanes in terms of the spatial coverage of rainbands before, during, and just after landfall, operational meteorologists will be better equipped to aid in public preparedness and provide improved rainfall forecasts to emergency management personnel. This research examines the structural changes in precipitation as hurricanes make landfall along the Gulf of Mexico and Atlantic coasts of the U.S. using three shape metrics; 1) area (2-D coverage), 2) closure (proportion around storm center), and 3) dispersion (spread away from storm center). Precipitation is subset into light (0.254 mmhr⁻¹ ) and heavy (5 mmhr⁻¹ ) rain rates in order to capture and compare the structural changes of 62 landfalling hurricanes between 1998 and 2014. I find that the average precipitation distributions of Gulf and Atlantic landfalling hurricanes at the time of landfall are similar; however, there are important changes in these distribution based on landfall location. Specifically, Gulf storms become larger and heavy rain contracts around the TC center, while Atlantic storms become asymmetric and spread out through landfall. These results demonstrate the importance of landfall location and the role that environmental factors may play in determining how hazards related to flooding can evolve along the U.S. coastline.

A década de 90 foi caracterizada por uma grande expansão no mercado Brasileiro e mundial de frutas, em especial nas frutas de outono, como o caqui Diospyros kaki L.). Embora a quase totalidade da produção nacional de caqui seja destinada ao mercado interno, o Brasil vem se consolidando nos últimos anos como país exportador dessa fruta para países do continente americano e europeu. Por essa razão, o cultivo dessa fruteira vem se constituindo numa importante atividade agrícola para pequenos produtores no Brasil. O conhecimento da fenologia e de como varia o conteúdo em carboidratos de reserva do caquizeiro em clima tropical é de grande importância para o estudo do desenvolvimento dessa espécie nessas condições. A falta informações dessa natureza para o caquizeiro cultivado no Brasil motivou o presente estudo com a variedade Rama Forte, a mais cultivada e consumida no país. O trabalho conduzido em um pomar localizado na área experimental, setor de horticultura, da escola Superior de Agricultura "Luiz de Queiroz" (ESALQ) em Piracicaba - SP, no período 2002/2003. A fenologia foi caracterizada desde a brotação das gemas até a abscisão foliar. A variação dos teores de carboidratos de reserva em ramos e em raízes é descrita tendo por base os diferentes períodos de coleta de material no campo, e discutidos em função dos estádios fenológicos da planta e das estações do ano. As plantas estudadas passaram pelos estádios de dormência, brotação, elongação, florescimento, frutificação, senescência e abscisão foliar. As curvas de crescimento do fruto exibiram o padrão sigmoidal duplo, sendo que o crescimento em diâmetro se antecipou em relação ao acúmulo de massa. O crescimento do cálice se estabilizou ao final do último estágio de desenvolvimento dos frutos. Da brotação das gemas no final do inverno até a maturação dos frutos no início do outono passaram-se 199 dias. Após o florescimento foram produzidos apenas frutos sem sementes, com duração de 161 dias até a sua maturação. Ocorreram dois picos no abortamento de frutos. Os primeiros sintomas de senescência das folhas foram registrados a partir do último estágio de desenvolvimento dos frutos, dois meses e meio após a formação da copa ter sido concluída. Da brotação das gemas até o completo desfolhamento somaram-se 287 dias no decorrer de toda a primavera, verão e outono. A análise dos teores dos carboidratos de reserva mostrou que ocorreram variações significativas (P ≤0,05) no teor de amido e de açúcares solúveis totais nos órgãos amostrados. O amido se constitui numa importante fonte de material de reserva a ser mobilizada durante o ciclo do caquizeiro. Em relação aos açúcares solúveis totais, o amido mostrou maiores variações significativas, tanto no ramo como na raiz ao longo do período estudado. A recomposição no estoque de carboidratos de reserva nos ramos e nas raízes ocorreu durante o período de atividade fotossintética. / The decade of 90 was characterized by a great expansion in the Brazilian and world-wide market of fruits, in special in the autumn fruits, as persimmon (Diospyros kaki L.). Although almost the totality of the national production of persimmon either destined to the domestic market, Brazil comes if consolidating in the last years as exporting country of this fruit for countries of the American and European continent. Therefore, persimmon crop comes if constituting in an important agricultural activity for small growers in Brazil. The knowledge of the phenology of persimmon tree and how their reserve in carbohydrate content varies in tropical climate is of great importance for the study of persimmon´s tree in these conditions. The lack of information of this nature for the persimmon cultivated in Brazil motivated the present study with the ‘ Rama Forte’ variety, the most cultivated and consumed in the country. The work was lead in an orchard located in the sector of horticulture, in the Escola Superior de Agricultura "Luiz de Queiroz" (ESALQ), in Piracicaba, SP, during 2002/2003 growing cicle. The phenology of tree was characterized from budbreak to leaf fall, and carboydrate reserves in stems and roots was described for different times of plant material collected in the field, and argued based on phenological stages. The mixed buds had passed the stages of dormancy, budbreak, shoot elongation, bloom, fruition, leaf senescence and leaf fall successively. The curves of growth of the fruit had shown the double sigmoidal standard and growth of fruit diameter preceded that of fresh and dry weight. Calyx growth stabilized in the end of the last stage of fruit development. From budbreak, in the end of winter to the maturation of fruits, in the beginning of autumn was recorded 199 days. Only seedless fruits were produced. From flowering to fruit maturity 161 days was registered. Two peaks in the abortion of fruits had occurred. The first symptoms of leaf senescence had been registered from the last stage of fruit development, two months after the canopy have been concluded. From budbreak to the complete leaf fall 287 days was recorded during all the spring, summer and autumn growing seasons. Starch and total soluble sugars content fluctuated in roots and stems throughout (P≤0,05) phenologycal stages of persimmons tree. Starch fluctuations showed to be more prone to significant variations in relation to the total soluble sugars in the stems as in the root. Two peaks of starch depletion was registered. The stem and root tissue started to accumulate starch during the net exporting photoassimilates by leaf photosynthesis. These results indicate that root and stem tissues play a role as a carbohydrate reserve pools to be mobilized for shoot elongation, flowering and for the maintenance of the tree during the lack of photosynthesis activity of persimmon tree.

A década de 90 foi caracterizada por uma grande expansão no mercado Brasileiro e mundial de frutas, em especial nas frutas de outono, como o caqui Diospyros kaki L.). Embora a quase totalidade da produção nacional de caqui seja destinada ao mercado interno, o Brasil vem se consolidando nos últimos anos como país exportador dessa fruta para países do continente americano e europeu. Por essa razão, o cultivo dessa fruteira vem se constituindo numa importante atividade agrícola para pequenos produtores no Brasil. O conhecimento da fenologia e de como varia o conteúdo em carboidratos de reserva do caquizeiro em clima tropical é de grande importância para o estudo do desenvolvimento dessa espécie nessas condições. A falta informações dessa natureza para o caquizeiro cultivado no Brasil motivou o presente estudo com a variedade Rama Forte, a mais cultivada e consumida no país. O trabalho conduzido em um pomar localizado na área experimental, setor de horticultura, da escola Superior de Agricultura “Luiz de Queiroz” (ESALQ) em Piracicaba – SP, no período 2002/2003. A fenologia foi caracterizada desde a brotação das gemas até a abscisão foliar. A variação dos teores de carboidratos de reserva em ramos e em raízes é descrita tendo por base os diferentes períodos de coleta de material no campo, e discutidos em função dos estádios fenológicos da planta e das estações do ano. As plantas estudadas passaram pelos estádios de dormência, brotação, elongação, florescimento, frutificação, senescência e abscisão foliar. As curvas de crescimento do fruto exibiram o padrão sigmoidal duplo, sendo que o crescimento em diâmetro se antecipou em relação ao acúmulo de massa. O crescimento do cálice se estabilizou ao final do último estágio de desenvolvimento dos frutos. Da brotação das gemas no final do inverno até a maturação dos frutos no início do outono passaram-se 199 dias. Após o florescimento foram produzidos apenas frutos sem sementes, com duração de 161 dias até a sua maturação. Ocorreram dois picos no abortamento de frutos. Os primeiros sintomas de senescência das folhas foram registrados a partir do último estágio de desenvolvimento dos frutos, dois meses e meio após a formação da copa ter sido concluída. Da brotação das gemas até o completo desfolhamento somaram-se 287 dias no decorrer de toda a primavera, verão e outono. A análise dos teores dos carboidratos de reserva mostrou que ocorreram variações significativas (P ≤0,05) no teor de amido e de açúcares solúveis totais nos órgãos amostrados. O amido se constitui numa importante fonte de material de reserva a ser mobilizada durante o ciclo do caquizeiro. Em relação aos açúcares solúveis totais, o amido mostrou maiores variações significativas, tanto no ramo como na raiz ao longo do período estudado. A recomposição no estoque de carboidratos de reserva nos ramos e nas raízes ocorreu durante o período de atividade fotossintética. / The decade of 90 was characterized by a great expansion in the Brazilian and world-wide market of fruits, in special in the autumn fruits, as persimmon (Diospyros kaki L.). Although almost the totality of the national production of persimmon either destined to the domestic market, Brazil comes if consolidating in the last years as exporting country of this fruit for countries of the American and European continent. Therefore, persimmon crop comes if constituting in an important agricultural activity for small growers in Brazil. The knowledge of the phenology of persimmon tree and how their reserve in carbohydrate content varies in tropical climate is of great importance for the study of persimmon´s tree in these conditions. The lack of information of this nature for the persimmon cultivated in Brazil motivated the present study with the ‘ Rama Forte’ variety, the most cultivated and consumed in the country. The work was lead in an orchard located in the sector of horticulture, in the Escola Superior de Agricultura “Luiz de Queiroz” (ESALQ), in Piracicaba, SP, during 2002/2003 growing cicle. The phenology of tree was characterized from budbreak to leaf fall, and carboydrate reserves in stems and roots was described for different times of plant material collected in the field, and argued based on phenological stages. The mixed buds had passed the stages of dormancy, budbreak, shoot elongation, bloom, fruition, leaf senescence and leaf fall successively. The curves of growth of the fruit had shown the double sigmoidal standard and growth of fruit diameter preceded that of fresh and dry weight. Calyx growth stabilized in the end of the last stage of fruit development. From budbreak, in the end of winter to the maturation of fruits, in the beginning of autumn was recorded 199 days. Only seedless fruits were produced. From flowering to fruit maturity 161 days was registered. Two peaks in the abortion of fruits had occurred. The first symptoms of leaf senescence had been registered from the last stage of fruit development, two months after the canopy have been concluded. From budbreak to the complete leaf fall 287 days was recorded during all the spring, summer and autumn growing seasons. Starch and total soluble sugars content fluctuated in roots and stems throughout (P≤0,05) phenologycal stages of persimmons tree. Starch fluctuations showed to be more prone to significant variations in relation to the total soluble sugars in the stems as in the root. Two peaks of starch depletion was registered. The stem and root tissue started to accumulate starch during the net exporting photoassimilates by leaf photosynthesis. These results indicate that root and stem tissues play a role as a carbohydrate reserve pools to be mobilized for shoot elongation, flowering and for the maintenance of the tree during the lack of photosynthesis activity of persimmon tree.

Plastificantes podem ser definidos como aditivos de baixa volatilidade utilizados para aumentar a processabilidade, flexibilidade ou diminuir a dureza de materiais poliméricos. Os ftalatos e adipatos utilizados como plastificantes, por sua baixa solubilidade em água e pelo alto coeficiente de partição octanol/água, tendem a se acumular no solo e sedimentos. Estes compostos são considerados potencialmente carcinogênicos, teratogênicos e disruptores endócrinos. A presente pesquisa compreendeu a biorremediação ex-situ do solo contaminado com resíduos de uma unidade industrial de plastificantes, utilizando reatores aeróbios, com microrganismos indígenas e exógenos adaptados através da adição de inóculo retirado da Estação de Tratamento de Efluentes por Lodos Ativados desta indústria. Foram avaliados os plastificantes: DIBP (Di-isobutilftalato), DBP (Dibutilftalato), DOP (Dioctilftalato),DIDP (Di-isodecilftalato), DIAP (Di-isoamilftalato) e DOA (dioctiladipato). Após a caracterização geotécnica do solo da área de plastificantes em 10 diferentes pontos, foram retiradas as quantidades para a biorremediação em 8 diferentes pontos (100kg/ponto) com os teores totais de plastificantes compreendidos entre 17 mg/kg solo a 6222 mg/kg solo. Análises mineralógicas, físicas e químicas foram realizadas posteriormente e indicaram que possivelmente a capacidade de troca catiônica do solo era devida aos plastificantes. Na biorremediação, os teores iniciais de plastificantes no solo, variaram de 85 mg/kg a 1688 mg/kg e após 120 dias de biodegradação em reatores aeróbios, as eficiências de remoção foram de 75 a 97%. Conforme as análises de fingerprint da comunidade bacteriana, ao final do processo, as bactérias presentes no solo eram originárias do lodo e do solo inicial e as análises de CGMS identificaram os metabólitos MEHP e os sub-produtos finais da biodegradação. / Plasticizers are low volatility compounds that offer flexibility and processability to resins. The phthalates and adipates, used as plasticizers, have low water solubility e high partition octanol/water(Kow) and accumulate in soil and sediments. This compounds are considered teratogenics, carcinogenics and as endocrine disruptors. This study evaluated the bioremediation of tropical soil contaminated with plasticizers process wastes, in aerobic conditions, with and without introduction of acclimated bacteria. After geological analysis of soil, considering ten differents points on the factory area, it was selected the soil for biodegradation of eight points (100kg/point) representing 17mg total plasticizers/kg soil to 6222mg total plasticizers/kg soil. Mineralogical, physical and chemical analysis were done and the results showed that perhaps the cationic change capacity was due to plasticizers. The plasticizers contents in soil were 85-1688mg/kg and after 120 days of biodegradation in eight aerobic reactors, the removal efficiencies were 75-97%. The fingerprint analysis showed that the final bacteria present in reactors originated from soil and sludge and the CGMS analysis identified the metabolic MEHP, and showed the sub-products and final products of biodegradation.

No description available.

acase@tulane.edu

The location of the Inter-Tropical Convergence Zone plays an important role in the climatology of tropical regions. Yet, despite its importance, the basic physics that determine the location of the ITCZ are not fully understood. Observational analyses show that, where the cross-equatorial pressure gradient is strong, the maximum convection is not necessarily associated with the highest sea surface temperature,or correspondingly, the lowest sea level pressure. Tomas and Webster (1997) argue that if a strong enough cross-equatorial pressure gradient exists and the system is inertialy unstable, secondary ameliorating circulations will drive strong off-equatorial convection in regions where ITCZ location is determined by low tropospheric dynamics. The observational record is re-examined to test the inertial instability hypothesis using the new ECMWF reanalysis data set. Composite analyses are performed to study the structure of the summer meridional circulation for the tropical Eastern Pacific Ocean and Atlantic Ocean. In agreement with Tomas and Webster theory, we find that the magnitude of the cross-equatorial pressure difference appears to determine the intensity of convection with low values of outgoing longwave radiation always to the north of the zero absolute vorticity line, and the absolute vorticity advection equatorward of the this line. Also the observed oscillation period of the disturbance for the studied regions coincides with theoretical oscillation period of the inertial flow.

An eddy-permitting 2-1/2-layer Reduced Gravity Ocean (RGO) model is developed. Compared with the conventional 2-1/2-layer RGO models, the new model has improvements in subsurface thermodynamics, vertical mixing scheme and open boundary conditions. Using this new 2-1/2-layer RGO model as a dynamical tool, a systematic investigation of the role of oceanic processes in controlling tropical Atlantic sea-surface temperature (SST) response to Atlantic Meridional Overturning Circulation (AMOC) changes is carried out by varying the strength of northward mass transport at the open boundaries. It is found that the North Brazil Undercurrent (NBUC) reverses its direction in response to a shut-down of the AMOC. Such circulation change allows warm waters of the northern subtropical gyre enter the equatorial zone, giving rise to a prominent warming in the Gulf of Guinea and off the coast of Africa. Sensitivity experiments further show that the SST response behaves nonlinearly to AMOC changes. The rate of SST changes increases dramatically when the AMOC strength is below a threshold value. This nonlinear threshold behavior depends on the position of subsurface temperature gradient. The new RGO is coupled to an atmosphere general circulation model (AGCM) (CCM3.6). The coupled model is capable of capturing major features of tropical Atlantic variability. With the aid of this coupled model, a series of experiments with different combinations of oceanic and atmospheric processes are carried out to elucidate the relative importance of the oceanic processes and atmospheric processes in AMOC-induced tropical Atlantic variability/change. It is found that the oceanic processes are a primary factor contributing to the warming at and south of the equator and the precipitation increase over the Gulf of Guinea, while atmospheric processes are responsible for the surface cooling of the tropical north Atlantic and southward displacement of ITCZ. The sensitivity of the coupled system to different strength of the AMOC is further investigated. It is found that equatorial SST and precipitation response also behaves nonlinearly to AMOC changes. The impact of AMOC changes on Tropical Instability Waves (TIWs) is assessed. It is found that the activity of TIWs is reduced in response to the AMOC-induced equatorial SST warming. Correlation analysis suggests that AMOC may affect TIW activities by modifying SST gradient north of the equator.

In this thesis we construct an analogue in tropical geometry for a class of Schubert varieties from classical geometry. In particular, we look at the collection of tropical lines contained in the fan tropical plane. We call these tropical spaces "tropical Schubert prevarieties", and develop them after creating a tropical analogue for flag varieties that we call the "flag Dressian". Having constructed this tropical analogue of Schubert varieties we then determine that the 2-skeleton of these tropical Schubert prevarieties is realizable. In fact, as long as the lift of the fan tropical plane is in general position, only the 2-skeleton of the tropical Schubert prevariety is realizable. / text