Remotely sensed drought index and its responses to meteorological drought in Southwest China

摘要

The extreme drought in Southwest China during 2009-2010 caused great damages to vegetation in that area. In this study, we analyse the relationship between remotely sensed drought monitoring and meteorological drought monitoring. Vegetation Health Index (VHI) was calculated using multitemporal Normalized Difference Vegetation Index and land surface temperature from 2001 to 2010. VHI was adopted to characterize vegetation responses to southwestern drought characterized by Standard Precipitation Index (SPI). At the beginning of drought, vegetation has little response (VHI ＞ 50). As drought aggravates, VHI shows consistent and significant response (VHI ＜ 30 in most areas). VHI and 3-month SPI have highest correlation for croplands, whereas VHI and 6-month SPI have highest correlation for forest. SPI and VHI have good spatiotemporal consistency during drought period in Southwest China. Our study proves meteorological drought index combined with remote sensing drought index can enhance our understanding of vegetation responses to drought threat.