Previous studies suggest an accelerated water cycle over the Tibetan Plateau (TP) in recent decades, mainly based on observed precipitation. However, the exact changes to evapotranspiration (ETa) over this period remain largely unknown. Although multiple ETa products for the TP region report that ETa experienced a significant increasing trend of around 8.4 ± 2.2 mm/10 a during 1982–2018, there exist large uncertainties in the annual ETa estimates over different climate zones. Here, we quantified and explained the ETa trend using a comprehensive process-based ETa model refined on ground-based observations from nine stations over the TP. Attribution analysis revealed that a large part of the increasing ETa trend was caused by higher temperature (53.8%) and more soil moisture (23.1%) caused by the melting cryosphere and increased precipitation. The increasing rate of ETa on the TP was approximately twice that of the global ETa, providing strong and independent evidence for an accelerated hydrological cycle. The dominant role of increased temperature in ETa implies a continued acceleration of the water cycle in the future.
2021-12-22
本研究所分析的样品来自于2018年8、9月采集的长江全流域河水样品。河水镁同位素和锶同位素都在中国科学院地球环境研究所（IEECAS）多接收电感耦合等离子体质谱仪（Thermo-Fisher Neptune plus MC-ICP-MS）上测试。其中，镁同位素的分析精度（2SD）在0.06‰以内, Sr同位素的分析精度（2SD）大部分在0.000020以内。长江干流的河水镁同位素δ26Mg值整体从上游到下游呈下降趋势，变化范围为上游源头的-0.59‰到下游的-1.36‰，主要支流变化范围为-1.00‰到-1.55‰。锶同位素变化范围从0.709894到0.711446。长江的源头段的河水镁同位素受到了次生碳酸盐矿物沉淀的分馏作用，干流中下游和主要支流受到了碳酸盐风化主导。锶同位素主要受到碳酸盐风化主导，下游有硅酸盐风化的贡献。数据结果可以用于研究青藏高原地区的现代风化过程。
2021-11-25
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