Processamento de imagens AVHRR/NOAA visando o monitoramento de estiagem

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

A great part of the Brazilian territory is vulnerable to the occurrence of frequent intense dry periods since there is a difference between the precipitation and the annual potential evaporation during the year. Some methods have been proposed to assess and monitor the occurrence of a drought, such as that ones based on agroclimatic indexes calculated with ground weather station data. Unfortunately, the high spatial and temporal variability of the rainfall in tropical regions and the low density of ground weather stations make difficult the operational use of these methods. New remote sensing techniques have been developed in order to monitor and assess droughts based on satellite data, such as those from the AVHRR/NOAA. This paper compares the vegetation indexes based on AVHRR/NOAA images with rainfall data of four ground stations located in the State of São Paulo on February/1999. This comparison has the objective to assess the operational use of vegetation indexes based on satellite data to monitor the occurrence of drought. Six free-cloud images were used among 16 available to calculate the vegetation indexes such as the NDVI (Normalized Difference Vegetation Index) and RATIO. These two indexes have responded quickly to the rainfalls registered on February/1999 showing potential to their use in methods of drought detection and monitoring. This kind of method seems to be more adequate to monitor the drought during the fall and winter in the South and Southest regions of Brazil since the rainfalls are caused by cold fronts and the number of cloudless days is larger. It can be useful also to detect dry periods in the beginning or the end of rainy season

ASSUNTO(S)

imagens multiespectrais secas monitoramento vegetal sensoriamento remoto meteorologia

ACESSO AO ARTIGO

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