基于S波段双偏振雷达和X波段相控阵雷达的强风暴观测分析OA

A storm event that affected Changsha on 24 April 2022 was analyzed by using multi-source observations,on the basis of data from an S-band dual-polarization radar and an X-band phased-array radar.The results are as follows:(1)This severe storm occurred under a synoptic situation characterized by a southwesterly low-level jet.Convective instability in the lower atmosphere and boundary-layer frontogenetical convergence induced by a surface convergence line provided the triggering mechanism.(2)The maximum reflectivity(DBZM)of the storm that produced the severe convective weather in Changsha remained persistently high,exceeding 70 dBZ.The initial increase followed by a decrease in the vertically integrated liquid water content(VIL)and the echo top height(ET)can serve as one indicator for identifying hail growth and subsequent descent.(3)The storm exhibited a distinct hook echo signature at low elevation angles,accompanied by high specific differential phase(KDP)and low differential reflectivity(ZDR)values.Vertical cross-sections revealed pronounced ZDR columns and KDP voids.The near-surface region of strong reflectivity(55-60 dBZ)corresponded to ZDR values below 0 dB,a correlation coefficient(CC)below 0.9,and KDP values reaching 1.7-2.4 °/km,suggesting that hailstones nearing the ground were coated with a thick water film.The ZDR column was accompanied by a distinct ZDR trough,which spatially corresponded to the occurrence of a thunderstorm downburst.(4)The X-band phased-array radar can more finely depict the evolution of the wind field within the rapidly evolving storm,proving more advantageous for the early warning and forecasting of sudden severe convective weather events that cause disasters.