CHANGES IN EVAPOTRANSPIRATION AND THE POTENTIAL DRIVERS IN ASIAN ARID REGIONS DURING 2003 TO 2017

Abstract. Evapotranspiration (ET) has changed greatly across the world in the past decades. There are various drivers that may affect the changes in ET. Understanding the changes in ET and the potential drivers is of great importance to water resources management in the arid regions. In this study, we examine the trends in ET using satellite-based data in the Asian arid regions from 2003 to 2017. Trends in different ET components, i.e., the evaporation from bare soil and transpiration from vegetation, are estimated to examine their respective contributions to the changes in ET. The results show that the evaporation from bare soil is the main component of ET and has contributed larger to the changes in ET from 2003 to 2017. Statistically significant increasing trend is mostly found in Southwest Pakistan, Northwest India, Southeast Iran, many areas in Northwest China, and some parts in South Kazakhstan. The relations between ET and the global sea surface temperature (SST) are also examined. It suggests that the interannual variation of ET is closely related to annual SST anomalies in most areas, especially in Kazakhstan, Turkmenistan, Northwest China, Southwest Pakistan, and some parts of eastern Iran. This analysis provides useful information for water resources management and planning with respect to forest and agricultural development in the Asian arid regions.