Clênia Rodrigues Alcântara

UMA TEORIA TERMODINÂMICA PARA BRISAS: TESTE UTILIZANDO SIMULAÇÕES NUMÉRICAS

In this work we test a thermodynamic theory for sea-land breeze coupled with valley-mountain breeze through tri-dimensional numeric simulations. We verify the presence of such a breeze in Northeast Brazils east coast and perform experiments with and without the topography of the region. Although the temperature contrast between two surfaces is important in forming the breezes, the thermodynamic efficiency is a key parameter for the breeze intensity. The presence of the slope causes the pressure difference between two points to increase during the day and to decrease during the night. This contributes for more intense daytime breeze and less intense nighttime ones. The maximum pressure drop occurs about three hours prior the maximum intensity of the sea breeze. This is because most of the available energy for the circulations is used to overcome dissipation, mainly during daytime. From a purely thermodynamic viewpoint, the slope of a mountain acts to intensifying the daytime breeze and to weaken the nighttime breeze.

INFLUÊNCIA DOS JATOS EM MÉDIOS E BAIXOS NÍVEIS NOS PROCESSOS DE NUVEM: ESTUDO NUMÉRICO DE UMA LINHA DE INSTABILIDADE AMAZÔNICA

Squall lines (SL) are multicellular storms and it is well known that factors such as vertical wind shear can act to organize their convection. However there is few evidences of how medium and low level jets can alter the cloud processes, and as a consequence to affect the intensity, duration and propagation of such systems. This work attempts to clarify those jets role by discussing a simulated case of an Amazon SL based on an atmospheric wind profile over Belem - Brazil at 12:00 UTC of May 30, 2008. To accomplish the proposed goal a set of eight numeric experiments, with different wind profiles was performed using the BRAMS model. The results showed that the occurrence of a deep and intense jet may increase ventilation in clouds, resulting in more evaporation and drying, i.e. more mass entrainment. If the entrainment is higher, it can influence downdrafts, cold pools, convergence ahead of the system, and updrafts, so that more energy can be available to the system. Thus, under these conditions SL are more likely to propagate at higher speed with longer life time.

PROFILE OF RURAL PRODUCERS IN SÃO JOÃO DO CARIRI MUNICIPALITY, AND ITS REFLEXES IN THE PRODUCTIVE PROCESS: BETWEEN THE TRADITIONAL AND THE MODERN

There is nowadays a strong appeal to the traditional agricultural practices, due to their conservationist character - although it should take caution when it comes to “traditional” and “modern” terms as they relate to agriculture, because the modern, if taken with proper precautions can be sustainable; and the traditional, opting for modern inputs, becomes as impactful as the first. This is the reality found upon profiles rising from both the producer and agriculture in the municipality of Sao Joao do Cariri, where while the production system practiced in more traditional forms of agriculture, also makes use of modern inputs (chemical products), endangering not only the physical integrity of people, but also contaminating the environment. This production system reflects the plight of farmers, who lack knowledge, assistance and technology to achieve high productivity and therefore better living conditions. Giving these issues, this study aims to analyze some indicators of deteriorating practices in smallholder agriculture in the county and raise the economic profile of local producers, through their practices. The results point to a commitment of half the production capacity, due to the adopted techniques.

LINHA DE INSTABILIDADE DA AMAZÔNIA: ESTUDO DE CASO E IMPORTÂNCIA DAS CARACTERÍSTICAS DO PERFIL DO VENTO NA SUA FORMAÇÃO E DESENVOLVIMENTO

Este trabalho consistiu em um estudo de caso de linha de instabilidade amazonica, primeiramente feito atraves de dados observados disponiveis e simulacoes numericas. Foram realizadas simulacoes homogeneas utilizando-se o modelo atmosferico de mesoescala BRAMS. Tais simulacoes foram processadas com o intuito de avaliar a importância do cisalhamento direcional e da intensidade do vento, ambos na vertical. Observou-se que as simulacoes foram bastante sensiveis as alteracoes implementadas nos perfis de vento que inicializaram o modelo. No caso simulado, em que nao se observou cisalhamento, inclusive direcional, o sistema que surgiu foi composto por uma celula com menos profundidade, de curta duracao e estacionaria. No caso em que se observou cisalhamento moderado em baixos e medios niveis (jato de baixos niveis), a simulacao ficou muito proxima do caso controle, em que teve a linha de instabilidade bem formada. E no caso com cisalhamento direcional no perfil do vento bastante pronunciado, formaram-se camadas de nuvens que cobriram uma area extensa.

Phenological Dynamics of Vegetation Using the Enhanced Vegetation Index (EVI) in Regions of Bahia State

The purpose of this study is to analyze the dynamics of EVI (Enhanced Vegetation Index) variability in different time scales of the different biomes in the state of Bahia. Images of the MODIS / Terra (Moderate Resolution Imaging Spectroradiometer) sensor with spatial resolution of 1km were used for the period between 2001 and 2015. For that, the methodology of the Wavelet Transformation (WT) was applied in each homogeneous region HR. The WT allows to identify in different scales important oscillations in the signal, through scales of energy and global power. Thus, it can be observed that the phenological pattern of vegetation predominates on an annual scale in almost all regions, except in HR1, HR4 and HR6 where interactions with smaller scales are detected: intrasazonal and seasonal to some years in the studied period. In this context, it was possible to identify that in the years where there were higher rates of EVI, there is an association with higher rainfall indices in different regions. Therefore, it can be said that EVI is also a good indicator of rainfall.

Estudo dos Padrões de Ventos Offshore no Litoral do Ceará Utilizando Dados Estimados pelo Produto de Satélites BSW

To know the spatial distribution of the wind patterns of a coastal region for monitoring the onshore and offshore wind potential goes through to the existence of a network of meteorological stations on the coast. On the coast of Ceará, a systematic analysis of the results obtained through prospective studies can be beneficial with the use of the results at 10 m estimated by satellites, BSW, with spatial and temporal resolution of 0.25° and six hours, respectively. In this work, BSW winds are validated in the vicinity of the coast of Ceará through oceanic buoys and anemometric towers. Verified its accuracy, these data are used to study spatial variability of sea winds in Ceará, in seasonal and interannual scale, and their correlation with the coastal winds.

Influência da Temperatura da Superfície do Mar na Ocorrência de Linhas de Instabilidade na Costa Norte e Nordeste do Brasil

Abstract This work aimed to verify the possible relationships of sampling points of the sea surface temperature spatially distrib-uted in the tropical Atlantic and the development of squall lines in North northeast coast of Brazil using techniques ofgeneralizedlinearmodeling.Forthis,weusedgeneralizedlinearmodelsfromthelinearregressionPoissonandnegativebinomial, for analysis of the relationship established by modeling was applied ANOVA variance test with significancelevel of 0.05 probability to determine which independent variables were more significant in modeling. Also the wastegenerated by the adjustment of the models in order to identify the distribution that best fitted the data were analyzed. AllstaticanalysiswasperformedinR.softwareAmongthe132pairsofobservations,themagnitudeofthecorrelationcoef-ficient of Pearson (r) ranged from 0.06 (p < 0.04) between (LI and TSM5) and 0.88 (p < 0.0001) (TSM2 and TSM5), de-spite relations TSM and episodes of LI present no linear relationship or perfect positive linear relationship between theRevista Brasileira de Meteorologia,

Estudo de Caso de um Distúrbio Ondulatório de Leste sobre o Estado do Rio Grande do Norte - Brasil

Disturbios ondulatorios de leste (DOL) sao sistemas atmosfericos presentes na regiao tropical, preferencialmente sobre areas dos oceanos Atlântico e Pacifico. Sobre o Atlântico sao identificados, inicialmente, proximos a costa oeste do continente Africano e se propagam embebidos no fluxo dos Aliseos, em forma de ondas que se deslocam de leste para oeste. No Atlântico tropical sul, os DOL atuam, preferencialmente sobre o leste do Nordeste do Brasil (NEB) contribuindo significativamente para os totais anuais de chuva. O presente trabalho analisa um caso de ocorrencia de um DOL sobre o NEB, no estado do Rio Grande do Norte, no dia 13 de Junho de 2014, fazendo o uso de dados de reanalise da componente meridional do vento e vorticidade relativa nos niveis de 850 hPa, agua precipitavel e dados observados de chuva. Observa-se que o DOL se intensifica entre os dias 12 e 13 de Junho, com valores de vorticidade negativa e agua precipitavel significativos, proximo a costa do NEB, e se apresenta inicialmente como uma extensao da atividade convectiva presente na ZCIT, desde o Oeste Africano. O DOL causou valores significativos de chuva, gerando deslizamentos de terra, alagamentos e problemas no trânsito de Natal, durante copa do mundo de futebol.

ESTUDO PRELIMINAR DA APLICAÇÃO DA TEORIA DE DUTOS ATMOSFÉRICOS ÀS LINHAS DE INSTABILIDADE AMAZÔNICAS

Este trabalho apresenta uma analise de perfis do vento e de temperatura potencial e temperatura potencial equivalente em sitios localizados proximos a cidade de Belem – PA as 00, 06, 12 e 18 UTC nos dias 20, 23, 24 e 25 de junho de 2011, sendo os dias 20 e 25 aqueles em que nao foram observadas a formacao de linhas de instabilidade (LI), e os dias 23 e 24, dias com a formacao desses sistemas. O intuito e averiguar caracteristicas termodinâmicas que diferencie dias com e sem LI e se a teoria de dutos atmosfericos pode ser aplicada para explicar o papel dos jatos de baixos niveis no processo de formacao e propagacao destas. Como resultados, obteve-se que o perfil de vento continua sendo elemento aparentemente decisivo e com grande contribuicao para o processo ja, que para os perfis de temperatura potencial, potencial equivalente e potencial equivalente de saturacao nao foi perceptivel diferencas entre os dias com e sem LI. A maioria das caracteristicas necessarias para a formacao dos dutos atmosfericos, como camadas estaveis estaticamente, profundidade adequada e um nivel critico, foram encontradas nos perfis estudados.