Climatology of warm‐season mesoscale vortices over the Tibetan Plateau: Key statistical features and common formation mechanisms

Abstract

During the warm season, the Tibetan Plateau serves as a key source region for mesoscale vortices, which significantly influence weather patterns across and downstream of the plateau. While Tibetan Plateau Mesoscale Vortices (TMVs) have been widely investigated, critical aspects including their vertical structure, common formation mechanisms, diurnal variability and the statistical characteristics of shorter‐lived TMVs (less than six hours) remain unquantified. To address these gaps, we analyze 42 warm seasons (1979–2020; May to September) using hourly ERA5 reanalysis. Results indicate that TMV formation is strongly terrain‐dependent, occurring more frequently at higher altitudes. Over 68% of TMVs last less than six hours, and more than 75% exhibit a shallow vertical extent (≤50 hPa). TMV‐related precipitation contributes approximately 13.8% of the total warm‐season rainfall over the Tibetan Plateau, with localized contributions reaching up to 36% in northwestern and central regions. TMV frequency peaks around 2200 h local solar time. Mechanistically, development is primarily driven by vertical stretching due to low‐level convergence. Favorable environmental conditions include warmer surface temperatures, higher convective available potential energy, stronger precipitation, upper‐tropospheric divergence, and mid‐level cyclonic vorticity. Furthermore, a strong steering flow, intense vortex core, deep vertical structure, and rapid enhancement of upper‐level cyclonic vorticity are essential factors enabling TMVs to move off the plateau.