厦门地区一次阵风锋与海风锋碰撞触发强对流的数值模拟OA

Using conventional observations,surface automatic meteorological station data,NCEP/FNL re-analysis,Doppler radar data,and WRF model simulations,this paper studies a severe convective event triggered by the collision between a gust front and a sea-breeze front in the Xiamen Region,and also ana-lyzes its underlying mechanisms.The results show that this event occurred at the edge of the subtropical high,where upper-level divergence overlapped with low-level convergence.An unstable thermodynamic stratification characterized by dry upper levels and moist lower levels,together with strong thermal insta-bility,provided a favorable environment for convective development.The cold outflow generated by earlier convective cells expanded outward forming a gust front,while the sea-breeze front developed continuously along the Xiamen coast.After the two boundaries collided near the urban area of Xiamen,low-level con-vergence and local lifting were markedly enhanced,thereby initiating the severe convection.WRF simula-tions further indicate that following the collision,the shallow-layer specific humidity in the collision zone increased by about 2.5 g·kg-1,the maximum convective available potential energy increased by more than 1000 J·kg-1,and the vorticity intensified to 25× 10-4 s-1,which indicate significant enhancement of moisture supply,instability,and dynamic lifting.The convergence-induced ascending motion allowed air parcels to overcome the level of free convection,thereby initiating and sustaining convection.Subsequent-ly,convective cells near the collision zone merged and triggered a cloud-bridge cell,which further devel-oped into a multicellular merging process.Thereafter,a surface convergence line and shallow shear system on the rear side of the collision area maintained a deeper convergence-ascending structure,and with suffi-cient moisture and instability,a subsequent convective regeneration process occurred.The findings could provide a useful implication for nowcasting and warning of local severe convection in Xiamen and other coastal regions.