Analysis on phased array weather radar detection of a short-term heavy precipitation

WANG Xuejing; ZOU Chao; WANG Yurun; YANG Min; ZHANG Yongxuan

doi:10.19513/j.cnki.hyqxxb.20250325001

Abstract：Short-term heavy precipitation is a leading disastrous weather occurring during the warm season in China.This study examines the meso-and small-scale characteristics of short-term heavy precipitation and the configuration of three-dimensional wind field in depth,using the heavy precipitation event of weak synoptic disturbance that occurred in Shanghai on 29 June 2022 as a case study.Utilizing observations of X-band phased array weather radar(XAWR),S-band dual-polarization Doppler weather radar,and surface and sounding data,the mechanisms behind this heavy rainfall and its developmental evolution are explored.The findings are as follows.(1)The event is a rainstorm that forms in the warm sector before the cold front,where the shallow cold air from the surface interacts with the warm and humid airflow,creating a mesoscale convergence line that triggers the convection.(2)During this heavy precipitation,the radar echoes experience three merging and intensifications.The first merging increases the echo intensity.In the second merging,multiple cells move towards southeast,and the diffusion of the sinking airflow from these cells in the lower layer intensifies the near-surface northerly airflow,continuously generating new cells at the southern edge of the thunderstorm.The multiple cells formed after the third merging move towards northeast,the outflow from the thunderstorm sustains the near-surface northerly airflow,and new cells are generated on the southern side of the echo.(3)The strengthening of southwesterly winds and the weakening of northerly airflow lead to a rapid decline in the radar echo intensity,signaling the end of this short-term heavy precipitation event.