Variações do albedo, NDVI e SAVI durante um ciclo da cana-de-açúcar no Norte Fluminense

Abstract

The albedo is an important parameter in the radiation balance of a surface and is commonly used in climate models and crop weather, such as estimates of the flow of water vapor and net radiation, among others, however, this parameter is not always available. The aim of this study was to show the variations of albedo, Normalized Difference Vegetation Index (NDVI) and Soil Adjusted Vegetation Index (SAVI) during the growing cycle of sugarcane. For the purpose a micrometeorological station was installed in an area of 13 ha in commercial cultivation of Farm Partido. The crop was regularly monitored at 85, 102, 128, 149, 174, 194, 215, 235, 255 and 280 days after cutting (DAC), to obtain the total dry weight and leaf area index (LAI). The albedo was obtained from the data generated by pyramometers, installed at the station. The SAVI and NDVI during the crop cycle were obtained from images Moderate Resolution Imaging Spectroradiometer (MODIS), Terra platform, with all the necessary computational algorithms implemented by the program Erdas 8.7. The albedo variations followed LAI. The NDVI and SAVI were influenced by water conditions of the period, but generally followed the variations of the LAI-albedo interaction.