Study on Drought Index Model of Arid Area in Central Guangxi Based on MODIS Data

Land surface temperature derived from brightness temperatures and NDVI from MODIS data are used to calculate TCI and VCI,respectively with which a dryness index(DI) is then constructed.The temporal-spatial distribution of drought in central Guangxi from September to November in 2004 and 2005 is studied by using the DI.DI's temporal-spatial pattern is compared with the real drought condition from the observatories around Guangxi,thus DI's validity in evaluating drought is verified.Afterward,the correlation coefficients of DI with TCI,VCI,LST and NDVI are evaluated.The results show that TCI and VCI have closer relation with drought than LST and NDVI,suggesting that dryness indexes based on TCI and VCI in this paper are reasonable for Guangxi central arid area.