第一届未来大气科学论坛

Polarimetric structures detected by radar can characterize the cloud microphysics and dynamics. Many studies have indicated that differential reflectivity (Z_DR) and specific differential phase (K_DP) columns, which serve as proxies for updraft strength, are related to lightning activity; moreover, the quantities of ice and supercooled liquid water strongly influence the occurrence of lightning flashes via noninductive charging. However, few studies have focused on clarifying the sequence or interactions among these factors from the perspective of the cloud life cycle. Here, we improve the ‘3D mapping columns’ method, which is based on the Cartesian grid datasets; this method is sensitive for identifying and quantifying the Z_DR columns in the early phase of cloud formation. Our study bridges the polarimetric structure and lightning activity within an isolated thunderstorm during the cloud life cycle. The results indicate that i) the parameter most relevant to total flashes/cloud-to-ground flashes is the content of supercooled rainwater/graupel. ii) The onset of the Z_DR column can be used to forecast lightning initiation in advance. iii) The signatures of the Z_DR and K_DP columns should be complementary and used to retrieve dynamic information instead of lightning activity. Notably, the variation in the Z_H intensity within Z_DR columns has high potential for predicting lightning activity during the cloud life cycle, which is valuable for exploration in the future. Our study improves the overall understanding of cloud microphysics and lightning activity, and suggestions for using these multiple polarimetric signatures to forecast severe weather are provided.

Thunderstorm,Lightning activity,Cloud microphysics,Polarimetric radar