Characteristics of the Tibetan Plateau vortices and the related large-scale circulations causing different precipitation intensity

Abstract

Tibetan Plateau vortices (TPVs) are important synoptic systems generated over the Tibetan Plateau, triggering heavy rainfall over southwestern and eastern China when they move off the plateau. In the present work, the precipitation associated with the moving-off TPVs is explored, and two groups of TPVs are selected according to the precipitation intensity (PI) related to the TPVs. The characteristics of these two groups of TPVs and the large-scale circulations during the period after the TPVs move off the plateau are compared. The results show that the impact of TPVs is mainly found in the region to the west of 115° E between 30° N and 36° N, becoming weaker along with the longitude. Sichuan Basin is the area with the greatest influence from the TPVs. PI is attributed to both the TPVs and the large-scale background. The TPVs related to high (low) PI are stronger (weaker) and travel further eastward (travel shorter distance), and the ascending motion associated with the TPVs is stronger (weaker) and deeper (shallower). The Western Pacific subtropical high (WPSH), southwesterlies to the south of TPVs in middle and lower troposphere, the South Asia High (SAH), and upper-level jet stream are crucial systems influencing the PI. Stronger and northwestward stretching WPSH, more intensive southwesterlies and the associated water vapor transportation to the south of TPVs, and stronger upper-level jet stream, as well as the more powerful and eastward extending SAH, correspond to higher PI, and vice versa.