The Remote Sensing Drought Index (RSDI) was developed based on 10 daily long term global coverage of NOAA/NDVI 8km coarse resolution data and Climatic Moisture and Evapotranspiration Drought Indices (EDI) based on FY-2 geostationary satellite data were applied in Mongolia.
The processed MODIS products as Normalized Difference Vegetation and Water Indices (NDVI, NDWI) can be used to indicate deficiencies in rainfall and portray meteorological and/or agricultural drought patterns both timely and spatially, thus serving as an indicators of regional drought patterns. NDWI holds considerable potential for drought monitoring because the two spectral bands (NIR and SWIR) used in its calculation are responsive to changes in the water content and inter-cellular air spaces of the spongy mesophyll layer of leaves in the vegetation canopy.
A new vegetation drought indicator, the Normalized Difference Drought Index (NDDI), is combines information from both the NDWI and NDVI data derived from MODIS data and NDDI was found to be more responsive and have wider dynamic range values than a simple NDVI-NDWI differencing through drought periods. According to the NDDI categories many countries use these values as, extremely wet, very wet, moderately wet, slightly wet, wet, normal, dry, mild drought, moderate drought, severe drought and extreme drought.