Using a convection initiation (CI) identification method and composite reflectivity (CR) data, 11,646 CI events (CIEs) were identified in the middle reaches of the Yangtze River Basin from May to September of 2016–2020. CIEs occur more frequently in July and August and from 11 to 16 BJT with a diurnal peak at 12 BJT. CI area (connected area with CR ≥40 dBZ) has a diurnal peak at 16 BJT related to the frequency of large-area CIEs (LACIEs, ≥62 km², 1%). Most LACIEs occur under stronger atmospheric instability and higher vertical wind shear with rapid intensification and expansion of convective regions after CI. Mountain CIEs, appearing under weak unstable stratification and low vertical wind shear, occur about twice as frequently as foothill or plain CIEs and are located over wetter soils than surroundings accompanied with the higher surface sensible heat flux and stronger soil moisture heterogeneity near CI locations.
 

Convection Initiation,Terrain,Yangtze River Basin