Roles of the Topographically-Affected Boundary Layer Low-Level Jet in the Moisture Transport Process of Nocturnal Rainstorms in Mountainous Areas around the Western Sichuan Basin

Fifteen cases were selected from May to September 2010 2021 study the moisture transport of nocturnal rainstorms in mountainous areas around western Sichuan Basin (western SCB). Nocturnal mainly occur along mountains southwestern SCB, 22 04 LST, peaking at 00 LST. The four following paths (proportions) obtained using Hybrid Single Particle Lagrangian Integrated Trajectory model (HYSPLIT): local path southeastern SCB (51.9%), southerly South China Sea (35.1%), northwestern Tibetan Plateau (TP) (6.6%), and easterly East (6.4%). persistent southwest monsoon is large-scale circulation for while boundary layer low-level jet (BLJ) over plays a key role diurnal variations SCB. To discuss roles topographically-affected BLJ transport, wind field decomposed into creeping flows (flows mountains) circumfluence mountains). At ageostrophic turn southeast due clockwise rotation caused by inertial oscillations BLJ, transporting directly converging because blocking effect TP. Meanwhile, opposite geostrophic meet accumulate “trumpet” topography leading convergence, budget peaks 2 h earlier than rainstorm peak. force upward motions conflict between warm–moist cold–dry downslope TP triggers convection, which significantly strengthens vertical velocity. results confirm existence both Eulerian viewpoints reveal process