Temporal variations of stable isotopic compositions in atmospheric water vapor on the Southeastern Tibetan Plateau and their controlling factors

Stable isotopic compositions in atmospheric water vapor ( 8 18 O V , 8 D V and d-excess V ) 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 8 18 O V and d-excess V 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 8 18 O V and d-excess V . The sharp decrease in 8 18 O V and increase in dexcess V 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.