A substituição do Cerrado mato-grossense para práticas agrícolas e a dinâmica fenológica alteram os índices biofísicos da superfície como a temperatura da superfície (Tsup) e o índice de área foliar (IAF). Assim, o objetivo desse estudo foi avaliar a variação do IAF e da Tsup por sensoriamento remoto em uma área de Cerrado no interior do estado de Mato Grosso. Imagens do sensor Thematic Mapper (TM) Landsat 5 foram utilizadas para estimar o IAF e a Tsup de uma área de Cerrado (CE), cana-de-açúcar (CA), pastagem (PA) e soja (SJ) em 2011. O IAF e a Tsup apresentaram correlação inversa. O IAF diminuiu e a Tsup aumentou ao longo da estação seca. Os maiores IAF e menores Tsup foram observados no CE, enquanto que os menores IAF e maiores Tsup foram observados na SJ. Os padrões temporais e espaciais do IAF e da Tsup na área de estudo ocorreram dirigidos pela precipitação, atividades antropogênicas e pelo próprio ciclo fenológico da vegetação.Palavras-chave: superfície do solo, antropização, aquecimento da superfície, sensoriamento remoto. INFLUENCE OF DEFORESTATION ON LEAF AREA INDEX AND SURFACE TEMPERATURE IN THE CERRADO OF MATO GROSSO ABSTRACT:The substitution of the Cerrado of Mato Grosso for agricultural practices and phenological dynamics alter the biophysical indexes of the surface such as surface temperature (Tsup) and leaf area index (LAI). Thus, the objective of this study was to evaluate the variation of LAI and Tsup by remote sensing in a Cerrado area in the state of Mato Grosso. The images of the Thematic Mapper (TM) Landsat 5 sensor were used to estimate the LAI and Tsup of an area of Cerrado (CE), sugarcane (CA), pasture (PA) and soybean (SJ) in 2011. The LAI and Tsup presented an inverse correlation. LAI declined and Tsup increased throughout the dry season. The higher LAI and lower Tsup were observed in the CE, while the lower LAI and higher Tsup were observed in SJ. The temporal and spatial patterns of LAI and Tsup in the study area were driven by precipitation, anthropogenic activities and by the phenological cycle of vegetation itself.Keywords: soil surface, anthropization, surface heating, remote sensing.

No abstract

The global and Amazon climate change, mainly in rainfall, due to the El Niño and La Ninã phenomena. The objective of this study was to analyze the relative frequency (RF) of rainfall, in different periods of the day, during occurrences of El Niño, La Niña events and neutrality condition. The research was carried out in the Southern mesoregion of the state of Amazonas (Apuí, Boca do Acre, Lábrea, Manicoré and Humaitá). Data were analyzed by the Spiegel´s method. The rainfall data were obtained from the Global Land Data Assimilation database from January 1st, 2000 to December 31st, 2018. Data were made available every three hours and integrated into six hours. RF of rainfall was higher in the afternoon in La Niña, Neutro and El Niño years in all municipalities. The RF in La Niña year was higher than during El Niño. The RF during the Neutral year was higher than during El Niño in Apuí and Boca do Acre, and had no difference in Lábrea, Manicoré and Humaitá. The rainfall in the southern Amazon mesoregion was more frequent during the afternoon.

A implantação de assentamentos rurais e a avaliação do efeito da dinâmica da mudança da cobertura nesses assentamentos é de extrema importância para determinação de políticas públicas. Assim, o objetivo desse estudo foi avaliar o impacto da implantação do assentamento rural Roseli Nunes e de sua dinâmica do uso do solo sobre parâmetros biofísicos da superfície. Para tanto, foram calculados o índice de vegetação da diferença normalizada (NDVI) e o albedo (αs), a temperatura (Ts) e o saldo de radiação (Rn) da superfície em áreas de preservação permanente, nativa, urbana, plantio de mandioca, plantio de banana, pastagem e solo exposto a partir de imagens Landsat 5 e Landsat 8. Os dados meteorológicos e as imagens de satélite foram obtidas durante o período seco nos anos 2000, 2010 e 2017. O NDVI e o Rn diminuíram e o αs e a Ts aumentaram entre 200 e 2010 em função da substituição da vegetação nativa em pequenas áreas agrícolas e urbanas. No entanto, apresentaram padrão inverso entre 2010 e 2017 no assentamento. As áreas de preservação permanente e nativas apresentaram os maiores valores de NDVI e Rn, e menores valores αs e Ts, enquanto as áreas com cultivos agrícolas, pastagem e solo exposto apresentaram menores valores de NDVI e Rn, e maiores valores αs e Ts. Por fim, os parâmetros biofísicos foram alterados significativamente com o desmatamento da área do assentamento entre 2000 e 2010, e a recuperação da vegetação entre 2010 e 2017, quando os valores dos parâmetros biofísicos foram próximos aos encontrados antes da implantação do assentamento.

The research on precipitation is related to analysis of its spatiotemporal variability using daily, monthly and annual data. However, there is a scarcity in the availability of information on how this variable is distributed over the hours of the day. Thus, the objective of this study was to analyze the intensity and hourly patterns of precipitation in Cuiabá in the State of Mato Grosso. Precipitation data were collected at the Cuiabá weather station of the National Institute of Meteorology from 2003 to 2018. The relative frequency of hourly precipitation was analyzed by the Spiegel method. The relative frequency of precipitation in wet season was high in the afternoon from 16:00 h (6.2%) to 17:00 h (5.9%) and low in the morning from 10:00 (3.0%) to 11:00 (2.8%). The relative frequency of precipitation during the dry season was high at 05:00 h (5.0%) and 17:00 h (5.4%) and low from 12:00 h (2.6%) and 13:00 h (2.2%). In general, the intensity of precipitation in the region was predominantly weak, followed by moderate, strong and very strong. The precipitation events in Cuiabá generally occur in the late afternoon, resulting from convective activity in the region.