Stable isotopic compositions in atmospheric water vapor (δO, δD and d-excess) are effective tracers that provide new insights into the local and regional hydrological cycle on the Tibetan Plateau. One-year continuous measurements of the isotopic compositions in near-surface atmospheric water vapor on the Southeastern Tibetan Plateau are reported. Our results demonstrated the relative impacts of moisture source shifts, large scale moisture transport, and local processes on the variability of the isotopic compositions in atmospheric water vapor. The observed seasonal variations in δO and d-excess exhibit low values in the monsoon period and high values in the non-monsoon period due to the predominance of large-scale atmospheric circulations. Local processes significantly modulate diurnal cycles of δO and d-excess. The sharp decrease in δO and increase in d-excess is related to the synoptic process. Moreover, the seasonality of moisture sources and transport, including moisture uptake and upstream rainout strongly affects the atmospheric moisture and the isotopes. These findings will improve our understanding of the regional hydrological cycle on the Southeastern Tibetan Plateau and provide reference to validate the simulated stable water isotopes.

中文翻译：

---

青藏高原东南部大气水汽稳定同位素组成的时间变化及其控制因素

大气水蒸气中的稳定同位素组成（δO、δD 和 d-excess）是有效的示踪剂，可为青藏高原局部和区域水文循环提供新的见解。报道了青藏高原东南部近地表大气水汽同位素组成的一年连续测量。我们的结果证明了水分源转移、大规模水分输送和局部过程对大气水蒸气中同位素组成变化的相对影响。由于大尺度大气环流占主导地位，观测到的 δ18O 和 d-excess 季节变化在季风期表现出较低值，在非季风期表现出较高值。局部过程显着调节 δ18O 和 d-过剩的昼夜循环。 δ18O的急剧减少和d-excess的增加与天气过程有关。此外，水分来源和运输的季节性，包括水分吸收和上游降雨，强烈影响大气水分和同位素。这些发现将提高我们对青藏高原东南部区域水文循环的认识，并为验证模拟的稳定水同位素提供参考。