Satellite characterization of terrestrial drought over Xinjiang Uygur Autonomous Region of China over past three decades

Satellite-based evapotranspiration (ET) estimation plays an important role in monitoring surface drought of the Xinjiang Uygur Autonomous Region of China (XUARC) because ET is a key indicator of drought severity. In this study, the evaporative wet index (EWI) is defined as the ratio of ET to potential ET (PET) based on a satellite-based hybrid Priestley-Taylor (Hybrid-PT) algorithm driven by the Advanced Very High Resolution Radiometer (AVHRR) Normalized difference vegetation index and the interpolated gridded meteorological data at a spatial resolution of 0.05 degrees. The estimated ET is rigorously validated with eddy covariance (EC) observations. The validation result shows that the root-mean-square error (RMSE) is 0.75 mm and the square of the correlation coefficients (R-2) for the Fukang (FK) site is more than 0.5 for the comparison between the ground-measured and estimated daily ET at the Fukang (FK) site. We found a good correspondence between their spatiotemporal patterns of both EWI and precipitation (P) anomalies. We also found that widely significant decreasing trends in EWI, ET and P appears from 1982 to 2009 in central regions of XUARC. The EWI can effectively reflect the variation in surface moisture and it has provided a favorable tool for regional drought monitoring.National Science and Technology Support Plan [2012BAC19B03, 2013BAC10B01]; Natural Science Fund of China [41201331, 41071020]; Scientific Research Project of Beijing Educational Committee [KZ201410028030]SCI(E)EIARTICLExiangliu135@yeah.net67