Abstract:In order to explore the detection ability of X-band phased-array radar for extreme precipitation, based on the basic products of X-band phased-array radar and three-dimensional wind field reversal from June to August in 2023 and 2024, the dual-polarization parameter characteristics of 9 extreme precipitation events in two years’ summer and the storm structure of 3 typical precipitation processes are analyzed by statistical and diagnostic analysis methods. The results show that the mean and median values of horizontal polarization reflectivity factor (ZH), differential reflectivity factor (ZDR) and specific differential phase (KDP) below 4 km gradually increase with the increase of minutely precipitation intensity. KDP increases most obviously. The KDP of super heavy precipitation >2.5 mm·min-1 increases by 30%-246% compared with the lowest level of 1-1.5 mm·min-1 at each altitude, and increases by 15%-167% compared with the lower level of 2-2.5 mm·min-1. ZH and KDP decrease with increasing altitude, and the maximum values are in the height of 0-1 km. The dual-polarization parameters of the lower layer gradually increase 3-10 min before the extreme minutely precipitation, and decrease 2-5 min after the extreme value, with the maximum fluctuation range of KDP. Under the 2 km height, the increase of KDP before the extreme value is 133%-205%, and the decrease range after the extreme value is 49%-55%. The intensity of the minutely precipitation depends mainly on the KDP (particle concentration). By analyzing the characteristics of extreme precipitation storm, we can see that the storm belongs to backward propagation type, with a new cell born every 4-6 min on the west side and its whole life span ≥65 min. There is a convergence zone of 4-5 km thick in the storm. The ZDR maximum center of the storm is below 3 km, and larger raindrops are concentrated in the lower layer. The possible reason for the increase of KDP laging behind the increase of ZDR is that during the descending process, the raindrops first grow in size and then break up into smaller high-concentration raindrops.