Abstract: Based on conventional meteorological observation data,FY-4A satellite data and ERA5 reanalysis data,this study analyzes the large-scale environmental background,dynamical conditions,as well as the forcing mechanism of meso-β scale deep convective cloud clusters and their feedback mechanism associated with a heavy rainfall event over the Bohai Rim region during 5-7 July,2022.The results show that under the joint influence of an upper-level trough and Western Pacific subtropical high,low-level shear line and low-level vortex provided favorable dynamic conditions for the development of convective cloud clusters during this heavy rainfall process.Within the cloud cluster group,meso-β scale deep convective cloud clusters formed and developed into multiple mesoscale rain bands.The cloud-top brightness temperature (TBB) of these deep convective clouds was below -52 ℃,with heavy precipitation generally occurring in regions of large TBB gradients near the cloud cluster peripheries.The interaction of unstable stratification,water vapor flux convergence,and slantwise updrafts further enhanced the intensification and maintenance of deep convective cloud clusters.Moreover,the centers of convective condensation latent heating and the convergence zones of the divergent component of Q vector showed good correspondence with heavy rainfall centers,which indicating that convective condensation latent heat release within and around the deep convective cloud clusters strengthened the upward motion,thereby affecting rainfall intensity.deep convective cloud clusters enhanced updraft intensity through convective condensation latent heating,thereby affecting precipitation intensity.

Key words: Cloud-top brightness temperature, Convective cloud cluster, Convective condensation, Latent heating