干旱区生态环境知识资源中心

The aim of this article is to study the spatial and temporal pattern of drought events in the Northeastern fringes of the Central Plateau of Iran using remote sensing and in situ meteorological data sets. Drought recognition is based on the analysis of the Standardized Precipitation Index (SPI) derived from meteorological variables such as rainfall, and indices derived from the Normalized Difference Vegetation Index (NDVI) obtained from the Advanced Very High Resolution Radiometer (AVHRR). The latter includes the Vegetation Condition Index (VCI), Land Surface Temperature (LST), thye Temperature Condition Index (TCI), Land Surface Moisture (LSM) and the Vegetation Health Index (VHI). Analysis is confined to the spring season from 1998 to 2004, inclusive. Results show that indices derived from the thermal bands have a higher sensitivity to drought conditions than indices derived from visible bands in this area. Indices derived from reflective bands such as NDVI and VCI seem to be better correlated to meteorological parameters than thermal band-derived indices like TCI. Indices that are calculated from both reflective and thermal bands such as LSM and VHI do not seem to be a reliable measure of drought conditions in this region.