Spatio-temporal variations of evapotranspiration and its driving factors on the Mongolian Plateau

Abstract

Evapotranspiration (ET) is a critical component for understanding global climate change, optimizing water resource management, and analyzing energy cycles. This study based on GLEAM evapotranspiration data, remote sensing vegetation data, and meteorological datasets, utilized Sen’s trend analysis, multiple regression, path analysis, and correlation analysis to investigate the spatiotemporal characteristics, primary drivers, and the impact of vegetation changes on ET and its components—soil evaporation (Eb), vegetation transpiration (Et), and interception evaporation from vegetation canopies (Ei) on the Mongolian Plateau. The findings reveal the following: (1) ET exhibits a decreasing spatial gradient from northeast to southwest across the Mongolian Plateau. Over the past four decades, ET and its components have shown an overall increasing trend, with particularly pronounced growth in the western regions. (2) In arid and semi-arid regions, vegetation transpiration (Et) is the primary contributor to ET, while canopy interception evaporation (Ei) contributes the least. Conversely, in humid and sub-humid regions, Et remains the largest contributor, whereas soil evaporation (Eb) exhibits the lowest contribution. (3) Changes in ET and Et are predominantly driven by direct effects of vegetation growth (positive effect) and indirect effects of relative humidity (negative effect). Meanwhile, Ei is primarily influenced by direct effects of precipitation. (4) Over the past 40 years, significant vegetation greening has occurred across the Mongolian Plateau, leading to enhanced ET. Notably, more than 70 % of the region shows a positive correlation between leaf area index (LAI) and ET.