Rainfall erosivities as defined by the R factor from the universal soil loss equation were determined for all events during a two-year period at the station La Cuenca in western Amazonia. Three methods based on a power relationship between rainfall amount and erosivity were then applied to estimate event and daily rainfall erosivities from the respective rainfall amounts. A test of the resulting regression equations against an independent data set proved all three methods equally adequate in predicting rainfall erosivity from daily rainfall amount. We recommend the Richardson model for testing in the Amazon Basin, and its use with the coefficient from La Cuenca in western Amazonia.

<p>This study examines whether and how land-atmosphere interactions can have an impact on the nocturnal convection over the Southern Great Plains (SGP) through numerical simulations of an intense nocturnal mesoscale convective system (MCS) on 19-20 June 2007 with the Weather Research and Forecasting (WRF V3.3) model. High-resolution nested simulations were conducted using realistic and idealized land-surfaces and two different planetary boundary layer parameterizations: Yonsei University (YSU) and Mellor-Yamada-Janjic (MYJ). All simulations show a persistent dry layer around 2 km during daytime and, despite ample instability in the boundary layer, the lack of a mesoscale lifting mechanism prevents precipitating convection in the daytime and in the evening ahead of the MCS passage after local midnight. Integral differences in timing and amount of MCS precipitation among observations and model results were examined in the light of daytime land-atmosphere interactions, nocturnal pre-storm environment, cold pool strength, squall line morphology and propagation speed, and storm rainfall. At the meso-gamma scale, differences in land-cover and soil type have as much of an effect on the simulated pre-storm environment as the choice of PBL parameterization: MYJ simulations exhibit strong sensitivity to changes in the land-surface in contrast to negligible impact in the case of YSU. A comparison of one-way and two-way nested MYJ results demonstrates that daytime land-atmosphere interactions modify the pre-storm environment remotely through advection of low-level thermodynamic features, which strongly impact the development phases of the MCS. At the end of the afternoon, as the boundary layer collapses, a more homogenous and deeper PBL (and stronger low level shear) is evident in the case of YSU as compared to MYJ when initial land-surface conditions are the same. For different land-surface conditions, propagation speed is generally faster, and organization (bow echo morphology) and cold pool strength enhanced when nocturnal PBL heights are higher and there is stronger low level shear in the pre-storm environment independently of the boundary layer parameterization. To elucidate the distinct roles of mesoscale transport and redistribution of low level instability (daytime remote feedbacks) and low level shear in the downwind pre-storm environment (nighttime local feedbacks), which is to separate the nonlinear land-atmosphere physical processes from PBL parameterization-specific effects on simulated storm dynamics, requires addressing the phase delay in storm development and propagation between the observed and the simulated MCS.</p><p>Another research objective was to examine the contribution of the land surface at short time scales. A second set of experiments was performed in which the land surface properties were homogenized every 5 minutes. The results show that surface effects are most pronounced during periods of insolation and, for the Yonsei University PBL parameterization, effects on the PBL height are most pronounced at the time of PBL collapse. Image processing techniques were found to be a useful measure of the spatial variation within fields. The results of this study show that, for this case, the integrated effect of the land surface can have a noticeable effect on convection, but such effects are not readily discernible at the 5-minute scale. While this study focused on the thermodynamic effects, further work should examine sensitivity to grid spacing and surface roughness.</p> / Thesis

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Apesar de sua importÃncia como grande produtor mundial, o Brasil tem participaÃÃo inexpressiva no mercado internacional de frutas. Parte da produÃÃo que nÃo atende aos critÃrios de qualidade mÃnimos para exportaÃÃo sÃo perdidos apÃs a colheita. Desta forma, estas frutas poderiam ser desidratadas para preservar parte da produÃÃo que nÃo à consumida ou exportada, aumentando desta forma a vida de comercializaÃÃo da fruta, reduzindo o peso para transporte e provendo maior renda ao produtor. A procura por alimentos de baixa caloria e adoÃantes nÃo calÃricos vem aumentando a cada dia. Os indivÃduos, que por diversas razÃes precisam substituir a sacarose por adoÃantes nÃo calÃricos, procuram por produtos que sejam dotados de gosto e caracterÃsticas prÃximas Ãs da sacarose, em virtude disso, o presente trabalho teve como objetivo avaliar os efeitos do ultrassom e da desidrataÃÃo osmÃtica como prÃ-tratamento ao processo de secagem, bem como a otimizaÃÃo deste para a produÃÃo de abacaxi (Ananas comosus) desidratado com valor calÃrico reduzido. Quando o abacaxi, na proporÃÃo 3:1 de Ãgua para fruta (p/p), sofreu aÃÃo do ultrassom de ponteira (200W), em Ãgua destilada como meio lÃquido, por 5 minutos, observou-se os maiores valores para, perda de Ãgua, perda de sÃlidos e difusividade efetiva. Nessa condiÃÃo a difusividade do abacaxi pÃrola aumentou 2,8 vezes, quando comparado ao abacaxi sem prÃ-tratamento (in natura), levando a uma reduÃÃo de 49,66% do tempo necessÃrio para remover 90% da Ãgua inicial dessa fruta, reduzindo o tempo total da secagem. Com a otimizaÃÃo dos dados do processo (proporÃÃo Ãgua/fruta 3:1 (p/p), por 20 minutos sobre ultrassom) seguido de impreguinaÃÃo em soluÃÃo de estÃvia a 10%, foi possÃvel reduzir o valor energÃtico do abacaxi em 17,97%, mantendo as cores da fruta in natura apÃs processamento. O que torna a utilizaÃÃo do ultrassom uma eficiente tecnologia na reduÃÃo de tempo de processamento de frutas secas e na participaÃÃo deste no desenvolvimento de novos produtos. / Despite its importance as a major world producer, Brazil has a minimal share in the international market of fruit. Part of the production that does not meet minimum quality standards for export is lost after harvest. Thus, these fruits could be dried to preserve part of production that is not consumed or exported, thereby increasing the shelf life of fruit, reducing shipping weight and provide more income to the producer. The demand for low-calorie foods and non-caloric sweeteners is increasing every day. Individuals, who for many reasons need to replace sucrose with non-caloric sweeteners, look for products that are provided with taste and characteristics similar to those of sucrose, as a result, the present study was to evaluate the effects of osmotic dehydration and ultrasound as pretreatment to drying process and the optimization for the production of dehydrated pineapple (Ananas comosus) reduced calorie. When the pineapple in the proportion 3:1 to fruit water (w / w), has the action of the ultrasound probe (200w) in distilled water as liquid medium for 5 minutes, there was the highest value, loss of water, loss of sound and effective diffusivity. In this condition the diffusivity of pineapple increased 2.8 fold when compared to non-pretreated pineapple (fresh), leading to a reduction of 49.66% of the time required to remove 90% of the fruit of the initial water, reducing the total drying time. By optimizing the process data (ratio water / fruit 3:1 (w / w) for 20 minutes on ultrasound) followed by impreguinaÃÃo stevia solution 10% was possible to reduce the energy value of the pineapple 17.97 %, keeping the colors of fresh fruit after processing. What makes the use of ultrasound technology in an efficient reduction of processing time of dried fruit and participation in the development of new products. Thus, the sonication figure as an alternative technology for obtaining reducing the processing time of fresh fruits of dried fruit and participation in the development of new products.

A Zona de Convergência do Atlântico Sul (ZCAS) é um fenômeno meteorológico que exerce um papel preponderante no regime de chuvas na região onde atua, acarretando altos índices pluviométricos na América do Sul. Este estudo mostra que, em uma análise de mesoescala, um Vórtice Ciclônico de Mesoescala (VCM) está associado à ZCAS através de um processo de retroalimentação. Este sistema é gerado dentro de um ambiente estratiforme na região da ZCAS, suga a umidade, acelera os ventos na vertical provocando intensa precipitação e, como conseqüência, pode afetar drasticamente as regiões atingidas provocando sérios danos sócio-econômicos. Este trabalho enfoca a atuação destes VCMs que se formam associados à ZCAS, identificando as propriedades termodinâmicas durante os diversos estágios de seu ciclo de vida. O trabalho é desenvolvido em três fases: (a) documentação da representação da precipitação e do transporte de umidade para a região da ZCAS através de conjuntos de reanálises de nova geração; (b) avaliação da importância da atuação dos VCMs embebidos na ZCAS, através do desenvolvimento de um sistema de detecção para determinação de estatística de ocorrência e (c) realização de simulações com o modelo de mesoescala BRAMS (Brazilian Regional Atmospheric Modeling System) para compreensão do comportamento de episódios específicos destes sistemas de mesoescala e sua relação com a ZCAS. A primeira parte do trabalho evidencia o avanço das novas reanálises da tentativa de representar de forma mais adequada à variável precipitação acumulada na região da ZCAS. A documentação é baseada em seis conjuntos de reanálises atmosféricas (MERRA, ERA-Interim, ERA-40, NCEP 1, NCEP 2 e NCEP CFSR) e cinco conjuntos de produtos observados de precipitação (SALDAS, CPC, CMAP, GPCP e GLDAS). Através das reanálises também foi avaliado o transporte de umidade sobre a região da ZCAS, para os anos de 1979 a 2007. Os diagramas de Taylor mostram que os produtos de precipitação estão bem correlacionados com o ponto de referência (CPC), com coeficientes entre 0,6 e 0,9. Somente a reanálise do NCEP CFSR possui correlações próximas as dos produtos de precipitação. Os VCMs, embebidos na banda de nebulosidade da ZCAS, são selecionados através de um critério objetivo de detecção, baseado na vorticidade e circulação do sistema, aplicado ao período de 2000 a 2009. Um total de 300 VCMs úmidos foram detectados na baixa troposfera, enquanto que na média e alta troposfera foram detectados 277 VCMs. Na baixa troposfera a maioria dos VCMs úmidos se localiza mais para SW na região continental costeira (ZCC) da ZCAS. Verifica-se também uma concordância entre os vórtices destas regiões de máxima vorticidade ciclônica e os extremos de precipitação. O estudo de dois casos específicos nas regiões da Continental Amazônica (ZCA) e ZOC, simulados através do modelo BRAMS, enfoca a relação entre a formação de mesovórtices e a atividade convectiva presente próximo à região de formação. Em ambas as regiões, os VCMs apresentam características similares, que podem ser consideradas como uma assinatura do sistema. Nos dois casos simulados estes sistemas apresentam o ciclo de vida inferior a 24 horas, escala espacial de aproximadamente 200 x 200 km2, intensa precipitação, deslocamento no mesmo sentido do escoamento na baixa troposfera, vorticidade relativa da mesma ordem de magnitude do parâmetro de Coriolis (10-4 s-1), núcleo quente acima do nível de máxima intensidade e um rápido crescimento do centro de vorticidade ciclônica principalmente nos baixos níveis. O balanço de vorticidade e o ciclo de energia desses sistemas são analisados. Pela comparação da chuva simulada com o produto Hidroestimador, sugere-se que o modelo BRAMS, com uma alta resolução espacial e temporal, melhora a representação do VCM, comparado com os dados da reanálise CFSR do NCEP. / The South Atlantic Convergence Zone (SACZ) is a meteorological phenomena that plays an important role in the precipitation regime over the region it covers, resulting in a high pluviometric indices in South America. This study shows, from the mesoscale analysis prospective that Mesoscale Cyclonic Vortex (MCV) is associated to the SACZ through a feedback process. This system is generated embedded in a stratiform environment within the SACZ region, taking moisture up, increasing vertical winds resulting in intense precipitation and consequently can affect drastically susceptible regions prone to natural disasters causing serious social and economic problems. This study highlights the MCVs associated to the SACZ, identifying the thermodynamic properties of the various stages during its lifetime cycle. This study is separated in 3 distinct parts as follows: (a) document the representation of the precipitation and moisture transport into the SACZ new generation reanalysis; (b) develop a detection system to compute the frequency statistics to assess the importance of the embedded MCVs to the SACZ and (c) use of the BRAMS (Brazilian Regional Atmospheric Modeling System) mesoscale model to understand specific MCVs episodes and its relationship with SACZ. In its first part, this work clearly shows the progresses made by the new reanalysis on the correct representation of the accumulated precipitation over the SACZ region. The documentation is based upon six atmospheric reanalysis datasets namely MERRA, ERA-Interim, ERA-40, NCEP 1, NCEP 2 and NCEP CFSR in addition to five precipitation products namely SALDAS, CPC, CMAP, GPCP and GLDAS. The reanalysis were also used to assess the moisture transport over the SACZ region from 1979 through 2007. Taylor plots show that the precipitation products are well associated to the reference dataset (CPC) with correlation coefficients varying between 0,6 and 0,9. Furthermore, only the NCEP CFSR reanalysis present precipitation correlation close to the abovementioned products. The MCVs embedded within the SACZ cloud bands are selected through an objective detection criteria based on the vorticity and circulation of the system, performed from 2000 to 2009. A total of 300 moist MCVs were detected in the lower troposphere whereas in the medium and high troposphere 277 were detected. Most of the MCVs in the lower troposphere were located in the Southwestern region of the continental coastal line of the SACZ and are possibly associated to topographic effects and local instability caused by incursion of transient systems into the SACZ region. Moreover, the vortices in this region match very well the regions of maximum cyclonic vorticity and maximum precipitation intensity. Two case studies were conducted over the Continental Amazonia Zone, simulated using the BRAMS model, showing the relationship between the mesovortices formation and the convective activity near its formation region. In both regions the MCVs present similar characteristics which could be considered as a \"signature\" for such systems. The case studies also present a lifetime shorter than 24 hours and spatial scale of approximately 200 km2 in addition to intense precipitation, shifting in the flow direction in the lower troposphere, relative vorticity of the same order as the Coriolis parameter (10-4 s-1), warm core above the level of maximum intensity and rapid growth of the cyclonic vorticity center mostly in the lower levels. The vorticity balance and the energy cycle of these systems is then analyzed. The simulated precipitation is compared against the Hidroestimador precipitation product. The results suggest that the BRAMS model, configured with high spatial and temporal resolutions improves the representation of the MCVs when compared to the NCEP CFSR reanalysis.

A commonly noted problem in the simulation of warm season convection in the North American monsoon region has been the inability of atmospheric models at the meso- scales (10 s to 100 s of kilometers) to simulate organized convection, principally mesoscale convective systems. With the use of convective parameterization, high precipitation biases in model simulations are typically observed over the peaks of mountain ranges. To address this issue, the Kain-Fritsch (KF) cumulus parameterization scheme has been modified with new diagnostic equations to compute the updraft velocity, the convective available potential energy closure assumption, and the convective trigger function. The scheme has been adapted for use in the Weather Research and Forecasting (WRF). A numerical weather prediction-type simulation is conducted for the North American Monsoon Experiment Intensive Observing Period 2 and a regional climate simulation is performed, by dynamically downscaling. In both of these applications, there are notable improvements in the WRF model-simulated precipitation due to the better representation of organized, propagating convection. The use of the modified KF scheme for atmospheric model simulations may provide a more computationally economical alternative to improve the representation of organized convection, as compared to convective-permitting simulations at the kilometer scale or a super-parameterization approach.

The aim of this diploma thesis is to investigate the influence of different types of HVAC system outlets on convective heat transfer from a human body. The first part of the thesis consists of an overview of essentials important for understanding the issue, specifically, metabolism, thermoregulation, heat transfer mechanisms, thermal vote and fluid dynamics. The second part defines the main working hypothesis and describes the used experimental approach leading either to confirmation or disproval of the hypothesis. The chosen approach is based on a measurement with thermal mannequin “Newton” using two different configurations: constant surface temperature and constant generated heat flux. In case of the first configuration, the convection intensity indicator was the value of heat flux generated from each of surface segments of the thermal mannequin. Their surface temperature was the indicator when running the experiment using the second configuration. The value was evaluated by the thermal mannequin as well as the thermal camera Flir i7 which provided more detailed division of the surface. The final part of the thesis describes the progress of the experiment itself, represents gathered values involving analysis of contaminants and confirms or disproves the original thesis.

Nanofluids are homogeneous mixture of dispersed solid particles in base fluids. These solid particles are usually smaller than 100nm. Suspended nanoparticles modify the properties of based fluids. It is claimed, in some literature, for nanofluids to have greater than expected heat transfer performance. Due to this, nanofluids have gained great attention from both research and development and industries active in cooling systems. This thesis reports several measurements of convective heat transfer coefficient in a horizontal open micro-tube test section under laminar flow regime. The test section has an inner diameter of 0.5mm made of stainless steel and it has a length of 30cm. Two different test sections have been built. The first one has 13 thermocouples attached on the wall and the second one has 10. These thermocouples are used to measure the wall temperature distribution along the tube. In addition, two more thermocouples are used inside the micro-tube, at the inlet and outlet, to measure the bulk temperature of the nanofluids. A syringe pump is used for injecting the nanofluids through the micro-tube. A DC power supply provides constant heat flux along the test section and a differential pressure transducer measures the pressure drop of the test section. Aqueous based Al2O3 (9 wt %), ZrO2 (9 wt %), TiO2(9 wt %), CeO2 (9wt %), CNT (0.15 wt %), and diamond (1 wt %) have been tested in this thesis. Local Shah’s correlation predicts very well the behaviour of these nanofluids. The results are compared with water in six different ways: heat transfer forconstant Reynolds numbers, volume and mass flow rates, pressure drops andpumping powers. Enhancement in heat transfer is recognisable only in thegraphs of Nu numbers for constant Reynolds numbers. This can be attributed to the higher viscosity for nanofluids. Moreover, friction factor for constant Reynolds numbers has been compared. All the nanofluids with the exception of Al2O3 and diamond suit quite well with Darcy-Weisbach correlation.

Deep convective clouds (DCCs) play a crucial role in redistributing latent heat, hydrological cycle and in the radiative budget of our climate system. Therefore, their complex evolution processes are in focus of many studies. Changes in the structure of DCCs can delay the onset of precipitation and alter the albedo of clouds. Knowing where in the cloud and under what circumstances the cloud liquid water droplets start to freeze is an important step to improve climate and weather forecast models. The purpose of this planned study is to characterize the impact of aerosol and thermodynamic conditions on the cloud particle growth. Therefore, ground-based cloud side observation of the reflected solar spectral radiation (near infrared) using an imaging spectroradiometer and measurements of the emitted thermal radiation using an infrared camera will be combined. These measurements will be taken at the Amazon Tall Tower Observatory, in the Amazon forest, Brazil. Here, the campaign will be introduced. / Hochreichend konvektive Bewölkung (deep convective clouds, DCCs) spielt eine entscheidende Rolle bei der Umverteilung latenter Wärme, sowie für den Wasserkreislauf und dem Strahlungshaushalt unseres Klimasystems. Aus diesem Grund stehen ihre komplexen Wolkenbildungsprozesse im Fokus vieler Untersuchungen. Veränderungen in der mikrophysikalischen Struktur der DCCs können das Einsetzen der Niederschlagsbildung verzögern. Darüber hinaus verändern sie die Albedo der Wolke. Das Wissen darüber, wo in der Wolke und unter welchen Umständen die Wolkentropfen beginnen zu gefrieren, ist ein wichtiger Schritt zur Verbesserung von Klima- und Wettervorhersagemodellen. Das Ziel der geplanten Untersuchungen besteht in der Charakterisierung des Einflusses von Aerosolpartikeln und thermodynamischer Bedingungen auf den Partikelwachstum und der Phasenumwandlung in Wolken. Hierzu werden bodengebundene Wolkenseitenbeobachtungen der reflektierten solaren Strahlung (nahes infrarot), aufgezeichnet mit Hilfe eines abbildenden Spektrometers, sowie Messungen der emittierten thermischen Strahlung, detektiert mit einer Infrarotkamera, kombiniert. Die entsprechenden Messungen werden am „Amazon Tall Tower Observatory“ im Amazonas Regenwald in Brasilien durchgeführt. Im folgendem wird die zugehörige Kampagne vorgestellt.

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