Rapid Intensification of Persistent Extreme Precipitation Over the Eastern Periphery of the Tibetan Plateau After 2000: The Role of Southwest Vortices

A notable increase in the intensity of Persistent Extreme Precipitation (PEP) events over the Eastern Periphery of the Tibetan Plateau (EPTP) is observed after 2000, which is strongly linked to the changes in Southwest Vortices (SWVs). A composited diagnostic of multiple SWVs is carried out in conjunction with the PEP. The Vorticity Vertical Transport (VVT) and Divergence (DIV) terms have a positive impact on the growth of SWVs, whereas the Relative Vorticity Advection (RVA) and Vorticity Tilt (VT) have a negative effect. Although all four terms are related to the variability of SWV intensity, DIV and RVA are the primary contributors to the increased trend in SWVs after 2000, accounting for up to 79.4% of the variation. The changes in meridional wind are thereby the main driver of the upward trend in PEP intensity, since it acts as the primary determinant of the long-term variations in the DIV and RVA.