Abrupt decline and subsequent recovery of extreme precipitation associated with Atmospheric Rivers in the Southeastern Tibetan Plateau

The Southeastern Tibetan Plateau (SETP), known as a crucial precipitation center within the Tibetan Plateau, has experienced frequent extreme precipitation events that have caused severe disasters. Atmospheric Rivers (ARs) have been recognized as significant contributors to extreme hydrological events, yet their characteristics and relationships with extreme precipitation in the SETP are not yet fully understood. In this study, we identified ARs using ERA5 reanalysis data from 1979 to 2023, quantified the variations in extreme precipitation associated with these ARs, and explored the underlying mechanisms driving these changes. The results demonstrated a critical role of ARs in modulating extreme precipitation over the SETP, Over the study period, a significant shift occurred in 1999 regarding ARs-related extreme precipitation. While this value increased prior to 1999, it experienced a sharp decline that year. Although a slight recovery was observed between 2000 and 2023, average levels remained below pre-1999 records. Fluctuations in ARs-related extreme precipitation are driven primarily by variations in ARs frequency, and the weakening of dynamic conditions associated with ARs may partly offset the enhancement effect of increased moisture availability, thereby limiting the intensification of extreme precipitation. Additionally, changes in atmospheric circulation further influence extreme precipitation by altering ARs pathways. This study enhances our understanding of the influence of ARs on extreme precipitation, providing critical insights into water resource management within the SETP.