湖北一次连续风暴中两次强对流卫星雷达特征及与闪电关系

2018年5月17-18日,湖北省一次连续强风暴过程中先后出现了不同类型的强对流天气.利用FY-4A卫星、雷达和地基闪电观测等资料,对相似环境背景下17日夜间鄂西北强对流(第1阶段,下同)和18日上午鄂东强对流(第2阶段,下同)的环境背景和天气系统特征等差异进行分析,提炼卫星雷达和闪电资料对分类强对流的预报依据.(1)...

SATELLITE AND RADAR CHARACTERISTICS OF TWO THUNDERSTORMS DURING A CONTINUOUS STRONG STORM IN HUBEI PROVINCE AND THEIR RELATIONSHIP WITH LIGHTNING ACTIVIT

From May 17 to 18, 2018, two thunderstorms occurred successively during a continuous severe storm in Hubei. Using data from FY-4 A satellite, radar and Advanced Toa and Direction system(ADTD), the present study analyzed the differences of environmental background and characteristics of the synoptic system of the two thunderstorms. Under similar environmental backgrounds, the first strong convection(referred to as the first stage) occurred in northwest Hubei at night on May 17 and the second(referred to as the second stage) happened in east Hubei on the morning of May 18. After the analysis, the basis for classification of strong convection by using satellite radar and lightning data were proposed. The results showed that: (1) The continuous strong storm was triggered by the warm shear line, which was resulted from the eastward movement of the southwest vortex, and the strong convection occurred in the convergence zone of the southwest airflow around the subtropical high and the east side of the vortex. At the first stage, cold advection developed in the middle and upper levels after the rapid eastward movement of short waves. The upper dry layer and the lower wet layer were favorable for the development of hail and gale. The second thunderstorm was in the warm humid air flow in front of the trough. The wet layer was deep, the sounding convection effective potential energy CAPE was moderately strong, and the probability of continuous heavy precipitation was relatively high. The meso-scale vortex on the ground promoted the development and maintenance of strong convection, and the southward movement of cold air on May 18 was the main reason for the heavy lightning at the second stage.(2) In northwest Hubei, the proportion of strong convective positive flashes was relatively large, and the peak time of positive flashes was almost the same as that of hail. The scattered flashes were distributed in the 35 ~ 50 dBZ echoes outside the range of strong echoes, and no flashes were observed in the strong echoes≥60 dBZ. In east Hubei, the strong convective lightning, especially negative lightning, was more frequent. The dense negative lightning was distributed in the 35 ~ 55 dBZ strong echo area, and the scattered positive lightning corresponded to the stratiform cloud of 25 ~ 35 dBZ around the strong echo. The above radar features could facilitate the classification and early warning of strong convection.(3) The data from FY-4 A Lightning Imager(LMI) and the low value area of cloud-top brightness temperature(TBB) were consistent with the detection positions of the ADTD. The total lightning of LMI and cloud to ground lightning of ADTD moved with the low-value center of TBB. The TBB of hail and convective gale was lower, which was below 230 K, and the heavy rainfall was between 250~ 270 K.