Abstract
Abstract. Actual terrestrial evapotranspiration (ETa) is a key parameter controlling land–atmosphere interaction processes and water cycle. However, spatial distribution and temporal changes in ETa over the Tibetan Plateau (TP) remain very uncertain. Here we estimate the multiyear (2001–2018) monthly ETa and its spatial distribution on the TP by a combination of meteorological data and satellite products. Validation against data from six eddy-covariance monitoring sites yielded root-mean-square errors ranging from 9.3 to 14.5 mm per month and correlation coefficients exceeding 0.9. The domain mean of annual ETa on the TP decreased slightly (−1.45 mm yr−1, p<0.05) from 2001 to 2018. The annual ETa increased significantly at a rate of 2.62 mm yr−1 (p<0.05) in the eastern sector of the TP (long >90∘ E) but decreased significantly at a rate of −5.52 mm yr−1 (p<0.05) in the western sector of the TP (long <90∘ E). In addition, the decreases in annual ETa were pronounced in the spring and summer seasons, while almost no trends were detected in the autumn and winter seasons. The mean annual ETa during 2001–2018 and over the whole TP was 496±23 mm. Thus, the total evapotranspiration from the terrestrial surface of the TP was 1238.3±57.6 km3 yr−1. The estimated ETa product presented in this study is useful for an improved understanding of changes in energy and water cycle on the TP. The dataset is freely available at the Science Data Bank (https://doi.org/10.11922/sciencedb.t00000.00010; Han et al., 2020b) and at the National Tibetan Plateau Data Center (https://doi.org/10.11888/Hydro.tpdc.270995, Han et al., 2020a).
Highlights
As the birthplace of Asia’s major rivers, the Tibetan Plateau (TP), famous as the “Water Tower of Asia”, is essential to the Asian energy and water cycles (Immerzeel et al, 2010; Yao et al, 2012)
The surface energy balance system (SEBS)-estimated ETa was validated against EC observations at six flux stations on the TP at a monthly scale (Fig. 2)
The SEBS model is capable of capturing both the magnitude and seasonal variation in the monthly ETa signal at all the six stations
Summary
As the birthplace of Asia’s major rivers, the Tibetan Plateau (TP), famous as the “Water Tower of Asia”, is essential to the Asian energy and water cycles (Immerzeel et al, 2010; Yao et al, 2012). Consuming around two-thirds of global terrestrial precipitation, evapotranspiration (ET) is a crucial component that affects the exchange of water and energy between the land surface and the atmosphere (Oki and Kanae, 2006; Fisher et al, 2017). As one essential connecting component between the energy budget and the water cycle in the terrestrial ecosystems (Xu and Singh, 2005), ET and its variations have been drawing more attention worldwide 2020); the terrestrial ET on the TP and its spatial and temporal changes remain very uncertain
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