Differences in triggering conditions between embedded and isolated convection initiation during a Meiyu season in China
Fan Zhang, Mingxin Li, Qinghong Zhang, Min Liu, Jun Xu, Jianping Guo, Huiyi Fan Abstract
The activity of the summer monsoon generates a complex convective environment and results in a large amount of convection initiation, whether embedded or isolated (i.e., ECI and ICI). However, there is still no consensus on how different are the triggering conditions that they undergo. For the first time, the respective spatiotemporal distributions of ECI and ICI, as well as their dependence on convective environments, lifting conditions, and their connection to monsoon circulations, are investigated statistically by using observations from radar and automated weather stations, reanalysis data, and a machine‐learning method during a Meiyu season over the Yangtze–Huai River Basin of China. The results show that ECI and ICI experience similar dynamic conditions but distinct thermodynamic convective environments due to the influence of a long‐lasting rain band. Consequently, ICI frequently occurs in the afternoon and around mountains, with a close connection to solar‐radiation‐induced atmospheric instability and topographic lifting but less sensitivity to circulation variations. In contrast, ECI exhibits a broader distribution over both plains and mountains, with two prominent peaks at 08:00 and 15:00 local time, and occurs more frequently when the front force was increased, resulting in more elevated initiation with convective updrafts generated above the boundary layer.