山东极端强降雨分钟雨量、Z-R关系和风暴结构演变特征

Analysis of Minutely Rainfall,Z-R Relationship and Structural Evolution for Extreme Rainfall Storms in Shandong Province

利用地面气象观测资料和多普勒天气雷达探测资料,对山东省2014—2016年31站次小时降水量超过80 mm强降水天气的分钟降水量变化特征、降水强度、Z-R关系、单体风暴参数特征和形态结构演变特征进行分析。结果表明,较大的对流有效位能(CAPE)值、较高的K指数和较低的抬升指数(LI),同时低层比湿在13 g·kg^(-1)以上时易发生小时极端强降水;强降水单体演变具有明显的"列车效应"或移动缓慢特征,具有"列车效应"特征的有15次,移动缓慢的有8次,同时具有两种特征的有8次,降水持续时间基本在57~58 min,5 min和6 min最大降水量均在15 mm和17 mm左右;用6 min最大降水量平均值17.3 mm作为强降水雨强,所对应站点低空反射率因子平均值为50.3 d BZ,Z-R关系近似于Z=200 R1.22;风暴最大反射率因子基本为50~59 d BZ,液态累积含水量(VIL)基本为15~40 kg·m^(-2),强回波中心高度基本在0℃层高度以下,风暴单体顶高8 km以上,回波顶高11 km以上,重心较低,降水强度大,适用于Z=200 R^(1.22)关系进行降水强度估测。

Based on the observations of automatic meteorological stations and Doppler radar data,the precipitation intensity,Z-R relationship,storm parameters and radar morphological characteristics of rainstorms with hourly rainfall more than 80 mm for 31 stations during 2014-2016 in Shandong Province were analyzed. The results show that larger convective available potential energy（ CAPE 500 J·kg-1）,higher K index（K≥33 ℃） and lower lifted index（LI≤-2 ℃）,and larger specific humidity（q≥13 g·kg^（-1）） at lower level were important factors resulting in hourly extreme rainfall. The evolution of heavy rainfall storms had＂train effect＂or slow moving characteristics. There were 15 storms with the characteristic of ＂train effect＂and 8 storms with slow moving characteristic,8 storms with both two features. The rainfall duration was about 57-58 minutes,the maximum rainfall of 5 minutes and 6 minutes was about 15 mm and 17 mm,respectively. Regarded the average value（17. 3 mm） of 6 minutes maximum rainfall as strong precipitation intensity,the corresponding average value of reflectivity factor was 50. 3 d BZ,the relationship between precipitation intensity and reflectivity factor fitted with the formula of Z = 200 R1. 22. In summer season,the maximum reflectivity factor of heavy rainstorms was between 50 and 59 d BZ,the vertically integrated liquid content ranged basically from 15 to 40 kg·m^（-2）,the height of strong echo center was basically below the height of 0 ℃ layer,the top height of storm cell was above 8 km,the echo top height was above 11 km,the precipitation efficiency was higher,and Z-R relationship were approximated to Z = 200 R^（1. 22）.