ABSTRACT This paper intends to briefly present some basic concepts on the microwave radiometry and radiometer calibration research in remote sensing applications and demonstrate results and analysis of the cryogenic calibration of a microwave ground-based radiometer currently deployed in scientific campaigns in Brazil. The equipment described in this text operates at 22 - 30 GHz and at 51 - 59 GHz frequency ranges and uses as the calibration standard a target cooled by liquid nitrogen. Since an accurate calibration (with observation errors below 0.5 K) is important to provide confidence in the retrieval of vertical temperature and humidity profiles, this work aims also to comment on some effects of the errors in calibration procedure on the atmospheric parameters of interest.

RESUMO A umidade do solo constitui-se num dos fatores principais para o estudo da seca, do clima e da vegetação. No caso da seca, esta é um fenômeno regional e afeta a segurança alimentar mais do que qualquer outro desastre natural. Atualmente, o monitoramento dos diversos tipos de seca é feito com base em índices que os padronizam em escala temporal e regional permitindo, com isso, a comparação das condições hídricas de diferentes áreas. Assim sendo, a fim de avaliar o impacto da umidade do solo durante os períodos de seca, o Índice de Severidade de Seca de Palmer foi estimado para toda a região do território brasileiro durante o período de 2000 a 2015, os quais incluem períodos com ocorrência de seca. Para isto foram utilizadas informações meteorológicas e pedológicas extraídas do modelo de balanço hídrico. A fim de avaliar as projeções de secas futuras, considerando o conjunto de dados de precipitação e de umidade do solo do Coupled Model Intercomparison Project Phase 5 (CMIP5) para o período de 2071-2100. Os resultados mostraram que o Índice de Seca de Palmer está diretamente associado aos padrões climatológicos de precipitação e de umidade do solo, em qualquer escala espacial e temporal (incluindo as projeções futuras). Assim sendo, conclui-se que este índice constitui de uma ferramenta importante para avaliar a umidade do solo em diferentes condições hídricas, bem como para a associação com informações econômicas e sociais para gerar mapas de riscos para subsídios aos tomadores de decisão.

ABSTRACT Soil moisture is a main factor for the study of drought impacts on vegetation. Drought is a regional phenomenon and affects the food security more than any other natural disaster. Currently, the monitoring of different types of drought is based on indexes that standardize in temporal and regional level allowing, thus, comparison of water conditions in different areas. Therefore, in order to assess the impact of soil moisture during periods of drought, drought Palmer Severity Index was estimated for the entire region of the territory. For this were used meteorological data (rainfall and evapotranspiration) and soil (field capacity, permanent wilting point and water storage in the soil). The data field capacity and wilting point were obtained from the physical properties of soil; while the water storage in soil was calculated considering the water balance model. The results of the PSDI were evaluated during the years 2000 to 2015, which correspond to periods with and without occurrence of drought. In order to assess the future drought projections, considering the set of the Coupled Model Intercomparison rainfall data Project Phase 5 (CMIP5). Climate projections precipitation in CMIP5 for the period 2071-2100 was extracted generating entitled forcing scenarios Representative Concentration Pathways - RCPs, and referred to as RCOP 8.5, corresponding to an approximate radiative forcing the end the twenty-first century of 8.5 Wm-2. The results showed that the PDSI is directly associated with climatological patterns of precipitation and soil moisture in any spatial and temporal scale (including future projections). Therefore, it is concluded that the PDSI is an important index to assess soil moisture different water conditions, as well as the association with economic and social information to create risk maps for subsidies to decision makers.

Os impactos da precipitação na qualidade da água ao longo do rio Purus, localizado no estado do Amazonas, foi investigado por meio de dados de precipitação, estimada por satélites, e informações sobre a temperatura da água, condutividade, pH, turbidez, oxigênio dissolvido e sólidos suspensos totais, adquiridas em quatro diferentes áreas ao longo do rio. Os resultados mostraram correlação negativa entre precipitação e turbidez e positiva entre precipitação e temperatura, condutividade, oxigênio dissolvido, sólidos suspensos totais e pH. O uso do solo, juntamente com o regime de precipitação, parecem ser os fatores principais que determinam a qualidade da água nos pontos de amostragem.

The impacts of precipitation on the water quality along the Purus River, located in the Brazilian State of the Amazonas, was investigated using data of precipitation estimated by satellite and information about water temperature, conductivity, pH, turbidity, dissolved oxygen and total suspended solids. The data were acquired in four different areas along the river. The results showed negative correlation between precipitation and turbidity. They also showed positive correlation between precipitation and temperature, conductivity, dissolved oxygen, total suspended solids and pH. The land use together with the rainfall regime seems to be the main sources of impact on the water quality around the sampling places.