Intensification of extreme precipitation across the Tibetan Plateau and its climatic drivers over 1982−2020

The Tibetan Plateau, known as the “Asian water tower”, plays a critical role in regional and global hydroclimate. However, a comprehensive understanding of the spatial and topographic variations in extreme precipitation and their underlying mechanisms over the Tibetan Plateau remains limited. Leveraging two state-of-the-art daily gridded precipitation datasets—the ECMWF ERA5 reanalysis and the High-accuracy Precipitation for the Third Pole (TPHiPr), we found that extreme precipitation (identified using the metric Rx1day (the maximum 1-day precipitation amount) and Rx5day (the maximum 5-day precipitation amount)) substantially increased during 1982−2020, with the trends becoming particularly pronounced in the last two decades (2001−2020). Spatially, changes exhibited a distinct dipole pattern, characterized by northward intensification contrasting with southward weakening. Topography strongly modulated these spatial patterns. Increases in extreme and mean precipitation were amplified at higher elevations and on gentler slopes, with changes in evaporation contributing more than those in atmospheric moisture convergence. Furthermore, precipitable water exerted a stronger influence than air temperature on both interannual variability and spatial heterogeneity of extreme precipitation. These findings deepen our mechanistic understanding of climate-induced changes in the hydrological cycle over the Tibetan Plateau.