Moisture Tracing for Rainy Season Precipitation over the Three-River Source Region of China

Abstract This study investigates the moisture sources during the rainy season (May–September) in the three-river source region (TRSR) of China from January 1980 to December 2017. The Flexible Particle dispersion model and the WaterSip method are employed to track and quantify moisture sources. It is found that external moisture enters the TRSR mainly from the midlatitude westerly and the Asian monsoon. The regions that contribute most to precipitation are the Qinghai–Tibet Plateau (QTP) and the South Asian monsoon region, which exceed three-quarters of the total. We also quantify the cascading moisture recycling through the QTP, where moisture from an earlier source produces precipitation over the QTP, which then evaporates and contributes to precipitation in the TRSR. More than 50% of the contribution from the QTP comes from the earlier source region through moisture recycling. In the wettest years, anomalous atmospheric circulation leads to more substantial moisture transport and vertical motion and more moisture translocated through the QTP, resulting in enhanced precipitation. The findings of this study will contribute to a more comprehensive understanding of the moisture sources and the atmospheric water cycle in the TRSR. Furthermore, they will provide valuable insights into watershed management and the optimal utilization of water resources.