Controls of the recent precipitation anomalies in the southeastern Tibetan Plateau: from the perspective of Indian summer monsoon activities and moisture sources

An increasing, but spatially inhomogeneous, trend in Tibetan Plateau (TP) precipitation, and especially the precipitation anomalies in southeastern TP (TPSE), has become the subject of major scientific concern. The Indian summer monsoon (ISM) is one of the TPSE's most important moisture sources, and its characteristics are therefore key for precipitation changes. Here we present the ISM activities (ISM onset/retreat date, ISM duration, and ISM intensity) and the percentages of varied moisture sources in TPSE, using OLR datasets and Hysplit modeling with gbl reanalysis. The recent precipitation anomalies in TPSE are analyzed with CMFD reanalysis. Major findings: (1) The ISM in TPSE generally begins later, retreats earlier, is of shorter duration, and weaker in intensity. (2) Uniformly decreasing (increasing) precipitation trends are found in TPSE for periods 1979 - 2018 and 1999 - 2018 (1979 - 1998). (3) Moistures along with the ISM are the primary controls of TPSE precipitation (similar to 85% in summer); these are also verified by the generally same linear trends observed in ISM moistures and TPSE precipitation in summer. (4) The precipitation anomalies in TPSE are closely related with the ISM activities: the ISM onset date (retreat date) and its variabilities affect precipitation during May - June (September - October); precipitation during July - August correlates positively with the ISM duration and its intensity. The ISM activities impact the percentages of ISM moistures and finally affect the precipitation amount and their trends. These results will contribute to precipitation-related studies as hydrology, ecology, and paleoclimate reconstructions in TP.