A New Angle-Based Spectral Index and Its Application in Drought Monitoring

An angle-based drought spectral index (ABDI) was proposed aimed to drought monitoring based on Near Infrared (NIR, 858 nm) and Shortwave Infrared (SWIR, 1240 and 1640 nm) bands of the Moderate Resolution Imaging Spectrometer (MODIS). The Shortwave Angle Slope Index (SASI) is reviewed and analyzed. United States Geological Survey (USGS) spectral datasets were employed to validate the ability of ABDI to estimate soil and vegetation moisture. Six-year(2002-2007) time series of Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI) and ABDI was created and analyzed for drought assessment and monitoring within the region of Nanchong in Sichuan Province, using MODIS history data and meteorological data. The investigation of a six-year history of MODIS NDVI, NDWI and ABDI indicates that a strong relationship exists among NDWI, ABDI and 2006 drought conditions of eastern Sichuan Basin. And the proposed ABDI had a stronger response to regional drought than NDVI and NDWI, which can be a practical method of drought monitoring in both accuracy and efficiency.