Resumo O sensoriamento remoto pode ser utilizado na estimativa de dados meteorológicos. A partir da utilização de imagens de variáveis atmosféricas obtidas pelo sensor AIRS (Atmospheric Infrared Sounder) a bordo do satélite Aqua, o presente estudo objetivou estimar as temperaturas máxima, mínima e média diária do ar na região do Distrito Federal – Brasil. Foram gerados modelos de regressão linear simples e múltipla tendo como variáveis explanatórias os dados do sensor AIRS de temperatura de superfície, umidade relativa do ar e vapor d’água atmosférico, obtidos em escala temporal de doze horas (diurno e noturno), durante o período compreendido entre janeiro de 2012 e dezembro de 2016. Como variáveis dependentes, foram utilizados valores observados de temperatura do ar em duas estações meteorológicas da região estudada. Os ajustes apresentaram R² = 0,62 e RMSE = 1,64 °C para os dados de temperatura máxima, R² = 0,59 e RMSE = 1,50 °C para os dados de temperatura mínima, e R² = 0,76 e RMSE = 1,45 °C para os dados de temperatura média. Conclui-se que os dados do sensor AIRS são adequados para o monitoramento da temperatura do ar na região do Distrito Federal.

Abstract Remote sensing can be used to estimate meteorological data. Images of atmospheric variables obtained by the AIRS (Atmospheric Infrared Sounder) sensor aboard Aqua satellite, were used to estimate maximum, minimum and average daily air temperature in Federal District region – Brazil. Simple and multiple linear regression models were used with explanatory variables derived of diurnal and nocturnal AIRS data of surface temperature, relative air humidity and atmospheric water vapor over the period 2012-2016. The dependent variables were the maximum, minimum and daily average air temperature obtained by two meteorological stations located in the study region. The AIRS fittings showed R² = 0.62 and RMSE = 1.64 °C for the daily maximum air temperature, R² = 0.59 and RMSE = 1.50 °C for the minimum daily air temperature, and R² = 0.76 and RMSE = 1.45 °C for the daily average air temperature. Our results suggest that the AIRS data can yield accurate daily air temperature estimates for Distrito Federal – Brazil region.

Abstract The Petrolina County, Pernambuco State, Brazil, presents specificities that make it unique from a hydrogeological point of view. Water resource scarcity is both a quantitative and qualitative issue. The climate is classified as semiarid, having low precipitation, along with high temperatures and evapotranspiration rates. Aquifer zones are related to low connected fractures resulting in a restricted water flow in the aquifer. The recharge is limited and the groundwater salinity is high. Stable isotope analyses of H and O were developed in groundwater samples (with different electrical conductivity) and surface water collected in a bypass channel flowing from the São Francisco River. The results were plotted in a dD ‰ versus δ18O ‰ graph along with the curves of the global and local meteoric water line. Groundwater samples showed unexpected results showing a lighter sign pattern when compared to the meteoric waters. More negative dD and δ18O values indicate an enrichment in light isotopes, which show that this process is not influenced by surface processes, where the enrichment occurs in heavy isotopes due to evaporation. The isotopic signature observed is interpreted either as resulting from the water-rock interaction, or as resulting from recharge from paleo rains. The waters are old and show restricted flow. So the water-rock contact time is extended. In the rock weathering processes, through the hydration of feldspars, there is preferential assimilation of heavy isotopes at the expense of the lighter ones that remain in the water. Analyses of the 87Sr/86Sr ratio and isotopic groundwater dating assist in the interpretations.