2024 Volume 80 Issue 16 Article ID: 23-16006
The purpose of this research is to analyze environmental conditions of stagnant frontal line-shaped convective systems, which trigger heavy rainfall disasters in Baiu season in Japan, using past events and considering spatial and temporal characteristics. As a result, type-A, which is large scale and occurs near convergence of Baiu front, occurs by large convergence of Baiu front, so the environmental condition of type-A is not necessarily idealized. On the other hand, type-B, which is small scale and occurs more than 100km away from Baiu front, occurs at more limited and idealized environment than type-A. We consider that strictly environmental conditions contribute to self-organized development of the first convective cloud. We also showed that requirements for occurrence of the first cloud are convective instable, large CAPE (Convective Available Potential Energy), and big change of direction of wind. Moreover, our results bring that the constant ratio of buoyancy to turbulence is important for occurrence and development of line-shaped convective systems.
