Regional variations in atmospheric moisture residence time (RT) highlight the need to obtain independent observation indexes to constrain different model-based estimates. Stable isotopes of oxygen and hydrogen naturally exist in water molecules that can provide such observational constraints. We analyzed the relationship between RT and precipitation isotopes (δ2H and δ18O) across different climatic zones in Eurasia from 1980 to 2020. Our analysis reveals that: (1) Both precipitation isotopes and RT showed significant increasing trends during 1980–2020. The increase in RT corresponds to weakened net isotopic distillation over Eurasia, suggesting reduced atmospheric circulation intensity under warming conditions. (2) The spatial patterns of RT and precipitation isotopes vary significantly among different moisture source regions, reflecting distinct moisture transport and precipitation formation processes. (3) On long-term scales, RT generally shows positive correlations with precipitation isotopes, except in plateau regions. The RT-δ18O relationship exhibits latitude-dependent variations, with similar slopes in regions sharing common moisture sources. These findings enhance our understanding of the long-term controls on precipitation isotopic composition and atmospheric moisture cycling patterns across Eurasia.

中文翻译：

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大气水分停留时间对欧亚大陆降水同位素影响的区域差异


大气水分停留时间 （RT） 的区域差异突出表明需要获得独立的观测指数，以限制不同的基于模型的估计。氧和氢的稳定同位素天然存在于可以提供这种观测限制的水分子中。我们分析了 1980 年至 2020 年欧亚大陆不同气候区的 RT 与降水同位素 （δ2H 和 δ18O） 之间的关系。我们的分析表明：（1） 1980—2020 年降水同位素和 RT 均呈显著增加趋势。RT 的增加对应于欧亚大陆上空的净同位素蒸馏减弱，表明在变暖条件下大气环流强度降低。（2） 不同水汽源区 RT 和降水同位素的空间模式差异显著，反映了不同的水汽输送和降水形成过程。（3） 在长期尺度上，RT 通常与降水同位素呈正相关，高原地区除外。RT-δ18O 关系表现出与纬度相关的变化，在共享共同水分来源的地区具有相似的斜率。这些发现增强了我们对整个欧亚大陆降水同位素组成和大气水汽循环模式的长期控制的理解。