Two types of heavy precipitation in the southeastern Tibetan Plateau.

Abstract

The southeastern Tibetan Plateau (SETP) is the preeminent summer heavy precipitation region within the Tibetan Plateau (TP). However, the large-scale circulation types and dynamics driving summer heavy precipitation in the SETP remain inadequately elucidated. Using the hierarchical clustering method, two distinctive atmospheric circulation patterns associated with heavy precipitation were identified: the Tibetan Plateau vortex type (TPVT, constituting 56.6 % of the events) and the mid-latitude trough type (MLTT, 43.4 %). A comprehensive examination of the two atmospheric circulation patterns reveals a clear nexus between the occurrences of summer heavy precipitation and positive vorticity anomalies, moisture convergence, as well as the southeastward displacement of the westerly jet core. Specifically, TPVT events are characterized by the eastward and dry-to-wet potential vorticity progression processes, while MLTT events are linked to the intrusion of a deep extratropical trough into the SETP. This study advances our understanding of the complex mechanisms governing the summer heavy precipitation in the SETP, shedding light on critical meteorological processes in the region.