Extreme Precipitation Events Associated with Tibetan Plateau Vortex

Extreme precipitation event (EPE) often brings disastrous consequences, such as floods, urban waterlogging, and landslides. The understanding of the effects of weather systems on EPEs can significantly improve weather forecast accuracy. In this study, the precipitation datasets from ERA-Interim, NOAA CPC and CMA station observations are used to quantitatively analyze the effects of Tibetan Plateau vortex (TPV) on EPEs over the TP and adjacent areas, based on an objective identification algorithm.

The results show that TPV has significant effects on EPEs in the TP and adjacent regions. In most areas of the TP, up to 60-80% of EPEs associate with TPV. Higher frequency of EPEs are identified at the center and southeastern edge of TPV. For the TPVs with- and without-EPE, its structure and circulation field are different significantly both at the higher and lower levels of troposphere. The TPVs resulting in EPEs usually consist of some specific synoptic components, namely, the southwest monsoon airflow along the southern side of TPV, the shear line, and the South Asia High at the higher level of the troposphere. In addition, TPV is also closely related with some other weather systems, such as the Southwest vortex which is a major concern for the TPVs moving off TP. The atmospheric circulation of TPV with the formation of extreme precipitation and the average state of the circulation are analyzed in detail to provide a better understanding for the purpose of prediction services.