Observation of the 19 June 2022 Tornado by X-Band Polarimetric Phased Array Radar in Foshan,Guangdong

ZHI Jiangling; BAI Lanqiang; HUANG Xianxiang; CAI Kanglong; ZHANG Jingjing; LI Zhaoming; HUANG Shuting

doi:10.16032/j.issn.1004-4965.2024.028

Abstract：Based on the data of an X-band polarimetric phased array radar and other multi-source observation data,we present in detail the environmental conditions and evolution of the radar signatures of an EF1 tornado that took place in Foshan,Guangdong on 19 June 2022.The tornado was spawned from a supercell that developed at the southern end of a squall line,which developed in an active southwesterly airflow environment after the onset of the southwest monsoon.The ambient atmosphere had all thermal and dynamic conditions that were conducive to the occurrence and development of supercell and tornado,such as strong convective instability energy,low lifting condensation level and strong vertical wind shear.The significant enhancement of the low-level storm relative helicity,supercell composite parameter and significant tornado parameter had a good indication for the occurrence of a supercell tornado.A polarimetric phased array radar with high spatial and temporal resolution at Nanhai detected the development process of a mini-supercell and the evolution characteristics of a tornado vortex.The convective storm gradually formed a hook echo and a reflectivity hole with the strengthening of a front low-level inflow.The mesocyclone formed at a height of more than 2.5 km and then extended to the lower level.With the strengthening of rear-flank downdrafts,the vortex rotation at the lower level was enhanced.When the rotation speed of the low-level mesocyclone exceeded 22 m·s-1(strong mesocyclone)and the diameter contracted to less than 1.5 km,the tornado was about to touch the ground.The appearance of tornado vortex signature(TVS)and tornadic debris signature(TDS)is the main feature of tornado occurrence.The tornado occurred near the reflectivity hole,TVS and TDS.