Drought monitoring with VHI computed from the improved MODIS LST

Vegetation Health Index is computed based on the vegetation index and land surface temperature which are very important satellite products for drought monitoring with remote sensing. The quality of Temperature Condition Index and Vegetation Health Index deeply depends on the quality of the Land Surface Temperature (LST). The present retrieval algorithm of Moderate Resolution Imaging Spectroradiometer (MODIS) LST products is quite good globally but for a local area there is still a room to improve by taking the effects of aerosol, water vapor, view zenith and observing time into account. The paper compared the MODIS LST with the observed surface temperature in weather station in the farming area of Eastern China. The correlations between the MODIS LST and the MODIS TPW, MODIS AOD, observing time, observing angle and DEM, respectively, were analyzed. And finally a regression equation to correct the temperature difference is formed and used to correct the MODIS LST retrieved from MODIS satellite. The results showed that the corrected LST is close to the observed with the decreased root mean square error and the increased correlation coefficient. The Vegetation Health Index was further calculated and used to monitoring the winter wheat drought in Eastern China. The drought situation was better captured by the improved VHI.