Avaliação de técnicas para obtenção do NDVI MSG de qualidade para monitoramento da superfície do solo

Abstract

Geostationary satellites represent a high temporal resolution alternative for ground surface monitoring compared to polar orbiting satellites. However, at high viewing angles, some factors influence surface reflectance, decreasing the quality of vegetation indices, reason why it is important to use atmospheric and geometric correction techniques. This article aims to evaluate data from the MSG (Meteosat Second Generation) geostationary orbit satellite to obtain the NDVI (Normalized Difference Vegetation Index) quality vegetation index in high viewing angle regions, having as study area the state of Goiás, in Brazil. MODIS (MODerate Image Spectroradiometer) images were used as a reference to identify temporal characteristics of the observations for product composition and to evaluate the performance of the evaluated techniques. The study database period was 2013-2015. As a result, the NDVI MSG, obtained from 10:00 to 12:00 local time, provides an image with 95% pixel coverage, within 12 days, while MOD09 gets it within 16 days. Geometric correction is a fine-tuning that did not present increased correlation of data. On the other hand, atmospheric correction maintains the correlation of the data and increases the value of NDVI, bringing it closer to the NDVI MODIS value. Performing a PCA (Principal Component Analysis) application using the unsupervised k-means classification technique, NDVI MSG provided superior results compared to MODIS, demonstrating the potential of geostationary data for soil surface monitoring.