Abstract: Land surface temperature(Ts) and enhanced vegetation index(EVI) derived from MODIS images were used to create the Ts-EVI space,from which a dryness index-Temperature Vegetation Dryness Index(TVDI) was calculated by the equation of dry and wet line.The soil moisture spatial patterns each sixteen days for summer drought period during 28 July to 28 August of 2006 in Hangzhou were reversed by using the TVDI and the soil moisture of the dry line calculated by using the field measurement data.The results showed that the TVDI method could be used to predict the soil surface moisture and the mean absolute error of the simulation results with the observed soil moisture were with 15%.The modified TVDI by elevation on Ts by referring to DEM could be better used to predict the soil moisture and the mean absolute error was reduced by 5%,compared to the soil moisture without modification.

Key words: TVDI(Temperature Vegetation Dryness Index), TVDI(Temperature Vegetation Dryness Index), Soil moisture, MODIS