Contrasting mechanisms of cross-regional heavy precipitation induced by an eastward-moving Tibetan Plateau vortex: Dynamical dominance versus thermodynamic maintenance

Climate warming and moistening are enhancing the frequency and intensity of Tibetan Plateau Vortices (TPVs), altering precipitation patterns across the Tibetan Plateau (TP) and adjacent regions. Although TPVs are the primary weather systems driving heavy precipitation over northern China, how their impacts vary across different geographic environments remains poorly understood. Reanalysis data and potential vorticity (PV) diagnostics are used to examine dynamical and thermodynamic processes associated with the TPV-induced cross-regional precipitation event (8–13 July 2021) across the Eastern Slope of the TP (ESTP) and the North China Plain (NCP). In the ESTP, heavy precipitation results from a dynamical-thermodynamic coupled mechanism, where low-level jets transporting moisture from the Indian Ocean and South China Sea interact with orographic lifting to trigger warm and moist advection, further enhanced by PV advection and diabatic heating. In the NCP, a dual-channel moisture transport pathway emerges as the TPV interacts with warm-moist flow along the western flank of the Western Pacific Subtropical High (WPSH), with precipitation peaks preceding PV maxima, indicating that dynamical forcing associated with PV advection dominates the heavy precipitation. These findings show that TPV-driven heavy precipitation results from spatiotemporal coupling between dynamical triggering and thermodynamic feedback of moisture. Latent heating rapidly amplifies nascent convection, while thermal processes enhance low-level instability, compensating for weakening dynamical forcing and sustaining precipitation. These findings highlight that regional disparities in TPV-induced heavy precipitation stem from asymmetrical dynamical-thermodynamic coupling, underscoring the need to elucidate the physical mechanisms by which TPVs trigger cross-regional precipitation, in order to improve forecasts of TPV-related weather and associated hazards. • The Tibetan Plateau Vortex (TPV) plays a critical role in the triggering and maintaining of heavy precipitation in northern China. • Heavy precipitation is characterized by a coupled pattern of “dynamical triggering, thermodynamic maintenance” in the Eastern Slope of the Tibetan Plateau. • Heavy precipitation relies on potential vorticity advection and a deeply moist troposphere structure in the North China Plain. • The asymmetric coupling between dynamical-thermodynamic processes reveals different mechanisms underlying TPV-triggered heavy precipitation.