2 research outputs found
Estimativa dos componentes do balanƧo de energia e da evapotranspiraĆ§Ć£o para Ć”reas de cultivo de soja no sul do Brasil utilizando imagens do sensor TM Landsat 5
Sazonalidade de variĆ”veis biofĆsicas em regiƵes semiĆ”ridas pelo emprego do sensoriamento remoto Biophysics variables seasonality on surface in semiarid regions by using remote sensing
Para investigar alteraƧƵes no albedo, no Ćndice de VegetaĆ§Ć£o por DiferenƧa Normalizada (NDVI), no saldo de radiaĆ§Ć£o e no fluxo de calor no solo, em decorrĆŖncia do regime pluviomĆ©trico no semiĆ”rido cearense, desenvolveu-se um estudo na bacia do Rio Trussu - CearĆ”, empregando-se sensoriamento remoto. Foram utilizadas duas imagens Landsat 7 ETM+, datadas de 25-10-2000 e 24-7-2001, sendo as variĆ”veis estimadas pelo emprego do algoritmo SEBAL (Surface Energy Balance Algorithms for Land). Os resultados mostraram que as variĆ”veis investigadas apresentaram alteraƧƵes entre as duas estaƧƵes, sendo os maiores valores de albedo registrados na estaĆ§Ć£o seca. O NDVI apresentou maior sensibilidade ao regime hĆdrico, mostrando alto potencial de recuperaĆ§Ć£o da vegetaĆ§Ć£o ao efeito da precipitaĆ§Ć£o. As margens do Rio Trussu apresentaram NDVI superior a 0,39, sendo indicativo de preservaĆ§Ć£o da mata ciliar. A vegetaĆ§Ć£o da bacia mostrou alto poder resiliente expresso pelo incremento nos valores de NDVI para o ano de 2001. A estaĆ§Ć£o chuvosa exerceu tambĆ©m influĆŖncia marcante sobre o saldo de radiaĆ§Ć£o e fluxo de calor no solo, confirmando o efeito da estaĆ§Ć£o climĆ”tica na modificaĆ§Ć£o do balanƧo de energia sobre a bacia.<br>To investigate the rainfall regime effects over the albedo, NDVI (normalized difference vegetation index), net radiation and soil heat flux in a semiarid region (Northeast of Brazil), a study in the Trussu watershed was developed by using remote sensing. The study focuses on two images (Landsat 7 ETM+) provided by Instituto Nacional de Pesquisas Espaciais (INPE), from October 25, 2000 and July 24, 2001, each of them having a different rainfall regime (dry and wet seasons). The images were analyzed by using the SEBAL algorithm (surface energy balance algorithm for land). The results showed that the amount of rainfall affected the investigated variables, and the highest values of albedo were registered during the dry season. The NDVI presented high sensibility to rainfall regime, pointing out a high vegetation potential recover during the rainfall season. The NDVI along the Trussu River was up to 0.39, expressing the repair zone preservation. The watershed vegetation showed a high resilience power expressed by NDVI values in the year of 2001. Net radiation and soil heat flux were greater in the dry season, in this way expressing the effect of humidity on the energy balance