Analysis of Evapotranspiration Variation Characteristics and Influencing&nbsp;Factors in Different Regions of the Tibetan Plateau

Chen Tingwei, Ma Yaoming, Xie Zhipeng, Wang Binbin, Zuo Hongchao

doi:10.7522/j.issn.1000-0534.2025.00048

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DOI: https://doi.org/10.7522/j.issn.1000-0534.2025.00048

Analysis of Evapotranspiration Variation Characteristics and Influencing Factors in Different Regions of the Tibetan Plateau

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1. College of Atmospheric Sciences，Lanzhou University，Lanzhou730000，Gansu，China；
2. Key Laboratory of Plateau Environmental Change and Surface Processes，Institute of Tibetan Plateau Research，
Chinese Academy，Beijing100029，China；
3. University of Chinese Academy of Sciences，Beijing100101，China；
4. China-Pakistan Earth Science Research Center，Chinese Academy of Sciences，Chengdu610299，Sichuan，China

Online published: 2025-05-20

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Abstract

To investigate the long-term variation characteristics of actual evapotranspiration（ETa）in different climatic regions of the Tibetan Plateau and its main influencing factors，as well as to enhance the understanding of land-atmosphere interactions and eco-hydrological processes in the plateau region，this study selected MA‐ WORS，BJ，QOMS，and SETORS as representative observational sites. Based on long-term site observations and satellite remote sensing data，the ETa at different temporal scales was calculated for each site，and its correlation with meteorological factors was analyzed. Furthermore，a path analysis method was employed to quantify the impact of environmental factors on daily ETa during the monsoon season. The results showed that：（1）In terms of annual ET a，BJ exhibited the highest value，with a multi-year average of 592. 17 mm，followed by SETORS at 521. 34 mm. MAWORS ranked third，with an annual ETa of 422. 84 mm，while QOMS had the lowest ET a of only 206. 33 mm，significantly lower than the other sites.（2）Regarding the ratio of annual ETa to precipitation，MAWORS had the highest value at 3. 34 due to its low precipitation. BJ followed with a ratio of 1. 11，while QOMS had a ratio of 0. 96，indicating a near balance in local water budget，with precipitation being the primary water source for ETa. SETORS exhibited the lowest ratio of 0. 68，suggesting a strong water retention capacity of the underlying surface，with a surplus of precipitation conducive to water resource accumulation and vegetation growth.（3）The interannual variation trends showed that annual ETa at MAWORS，BJ，and SETORS displayed an increasing trend. The increase at MAWORS was mainly attributed to the continuous enhancement of net radiation，while the rise in BJ was closely related to an increase in soil moisture content. The upward trend at SETORS was primarily driven by rising temperatures. In contrast，QOMS showed a decreasing trend in ETa， mainly due to a reduction in precipitation during the monsoon season.（4）ETa at different sites was controlled by various environmental factors. At MAWORS，ETa was primarily regulated by net radiation and soil moisture con‐ tent，with glacier meltwater serving as a significant water source. At QOMS，where the terrain acts as a barrier to water vapor transport，ETa was predominantly controlled by precipitation，showing a clear water-limitation effect. At BJ，ETa was jointly regulated by net radiation and soil moisture，with a stronger energy-limitation effect. At SETORS，abundant precipitation resulted in weak water limitations on ETa，making it mainly influenced by net radiation and temperature.（5）The regulatory effect of vegetation cover on ETa was more evident at BJ and SETORS，whereas at MAWORS and QOMS，the correlation was weaker due to sparse vegetation.（6）During the non-monsoon period，water vapor supply decreased significantly at all sites. Except for SETORS，soil at the other sites remained frozen，with soil moisture content reaching its lowest level of the year. Consequently，the ET a process was mainly controlled by net radiation. At SETORS，where water vapor transport was reduced，ETa relied more on precipitation supply.

Key words： Tibetan Plateau; Diurnal Evapotranspiration; Variation Characteristics; Influencing Factors

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Chen Tingwei, Ma Yaoming, Xie Zhipeng, Wang Binbin, Zuo Hongchao . Analysis of Evapotranspiration Variation Characteristics and Influencing Factors in Different Regions of the Tibetan Plateau[J]. Plateau Meteorology, 0 : 1 . DOI: 10.7522/j.issn.1000-0534.2025.00048

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