Spatially coherent clusters of summer precipitation extremes in the Tibetan Plateau: Where is the moisture from?

Atmospheric moisture dynamics for extreme precipitation is poorly understood in the Asian water towers. Using a new spatial clustering approach for extreme events, the Tibetan Plateau (TP) is divided into coherent sub-areas, where the magnitude of Summer Precipitation Extremes (SPEs) decreases from southeast to northwest in the past decades. There are two dominant pathways of external moisture convergences: one from the south, the other from the west, which are regulated by Indian monsoon and Westerlies, respectively. As Yarlung Zangbo Ground Canyon provides a natural passage for water vapor transport, SPEs in the southeast clusters absorb with around 75% of total moisture from the Bay of Bangla. The onset of SPEs in the southeast is also found earlier than the other clusters across the TP. Local recycling is another important moisture source for SPEs in areas with large water bodies. Moreover, teleconnections are initially examined between large-scale climate signals and moisture trajectories under the extreme events, demonstrating the potential influence of atmospheric circulations on SPEs in the TP.