季风涌背景下福建暴雨过程的触发机制研究OA

Based on conventional meteorological observations,ERA5 upper-air reanalysis data,FY-2G infrared cloud imagery,and FY-4A satellite cloud-top brightness temperature(TBB)data,this study employed the meso-scale WRF model to perform a numerical simulation and diagnostic analysis of a shear-type warm sector rain-storm that affected Fujian,Jiangxi,and adjacent regions during 13-14 June 2022.The results indicate that:(1)the low-level shear line was the primary mesoscale system responsible for the development of the rainstorm,and its eastward intensification played a key role in triggering the convective systems associated with the heavy rainfall;(2)a pronounced monsoon surge associated with the monsoon trough and its eastern flank supplied abundant moisture,enhancing the southwesterly warm-moist airflow,which converged with the northwesterly dry-cold airflow guided by the upper-level trough over the southeastern Wuyi Mountains,thereby initiating strong convection;(3)the rainstorm occurred under favorable stratification and vertical circulation conditions,where the continuous transport of low-level warm-moist air,together with pronounced upper-level divergence and low-level convergence,induced vigorous vertical ascent,sustained instability in the mid-lower troposphere,and continuously triggered new convective cells,maintaining persistent heavy rainfall;and(4)The WRF model adequately reproduces the spatial and temporal distribution characteristics of precipitation,with a TS score of 0.33 and a bias of 0.79 for 24-hour accumulated precipitation at the heavy rainfall level(≥50 mm).Further-more,potential vorticity effectively captured the dynamical and thermodynamical characteristics of the event,with high potential vorticity anomaly regions corresponding spatially to the rainstorm area,and the rainstorm center frequently located to the south of the high-value anomaly zones.