Exploration of the spectral space based on vegetation index and albedo for surface drought estimation

In this paper, a simple surface dryness index (Vegetation Condition Albedo Drought Index, VCADI) based on the spectral patterns of surface moisture in two dimensional spectral space of vegetation index versus broadband albedo is suggested. VCADI derived from multi-sources remote sensing data including the Thematic Mapper (TM), the Enhanced Thematic Mapper Plus (ETM+) and the MODerate Resolution Imaging Spectroradiometer (MODIS) images are significantly related to field measured soil moisture over different eco-systems. Spatio-temporal patterns of VCADI are further analyzed using time series of MODIS data over Ningxia Huizu Autonomous Region of China. Results indicate that VCADI variations are accordant with regional rainfall dynamics and the index has a potential in drought estimation as a simple satellite derived method completely independent of surface ancillary data.