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

Abstract

To investigate the long-term variation characteristics of actual evapotranspirationETain different climatic regions of the Tibetan Plateau and its main influencing factorsas well as to enhance the understanding of land-atmosphere interactions and eco-hydrological processes in the plateau regionthis study selected MA‐ WORSBJQOMSand SETORS as representative observational sites. Based on long-term site observations and satellite remote sensing datathe ETa at different temporal scales was calculated for each siteand its correlation with meteorological factors was analyzed. Furthermorea path analysis method was employed to quantify the impact of environmental factors on daily ETa during the monsoon season. The results showed that:(1In terms of annual ET aBJ exhibited the highest valuewith a multi-year average of 592. 17 mmfollowed by SETORS at 521. 34 mm. MAWORS ranked thirdwith an annual ETa of 422. 84 mmwhile QOMS had the lowest ET a of only 206. 33 mmsignificantly lower than the other sites.2Regarding the ratio of annual ETa to precipitationMAWORS had the highest value at 3. 34 due to its low precipitation. BJ followed with a ratio of 1. 11while QOMS had a ratio of 0. 96indicating a near balance in local water budgetwith precipitation being the primary water source for ETa. SETORS exhibited the lowest ratio of 0. 68suggesting a strong water retention capacity of the underlying surfacewith a surplus of precipitation conducive to water resource accumulation and vegetation growth.3The interannual variation trends showed that annual ETa at MAWORSBJand SETORS displayed an increasing trend. The increase at MAWORS was mainly attributed to the continuous enhancement of net radiationwhile 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 contrastQOMS showed a decreasing trend in ETa, mainly due to a reduction in precipitation during the monsoon season.4ETa at different sites was controlled by various environmental factors. At MAWORSETa was primarily regulated by net radiation and soil moisture con‐ tentwith glacier meltwater serving as a significant water source. At QOMSwhere the terrain acts as a barrier to water vapor transportETa was predominantly controlled by precipitationshowing a clear water-limitation effect. At BJETa was jointly regulated by net radiation and soil moisturewith a stronger energy-limitation effect. At SETORSabundant precipitation resulted in weak water limitations on ETamaking it mainly influenced by net radiation and temperature.5The regulatory effect of vegetation cover on ETa was more evident at BJ and SETORSwhereas at MAWORS and QOMSthe correlation was weaker due to sparse vegetation.6During the non-monsoon periodwater vapor supply decreased significantly at all sites. Except for SETORSsoil at the other sites remained frozenwith soil moisture content reaching its lowest level of the year. Consequentlythe ET a process was mainly controlled by net radiation. At SETORSwhere water vapor transport was reducedETa relied more on precipitation supply.

Cite this article

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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