摘要
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)此次连续强风暴是副高稳定维持,西南涡东移,暖式切变线触发形成的,强对流出现在副高外围西南气流和低涡东侧的辐合区中,第1阶段短波快速东移后中高层转为冷平流,上干下湿的层结利于冰雹和大风出现,第2阶段则处在槽前暖湿气流中,湿层深厚,探空对流有效位能CAPE中等强度,出现持续性强降水的概率较大。地面中尺度涡旋促使强对流发展维持,18日冷空气南下是第2阶段雷电密集的主要原因。(2)鄂西北强对流正闪比例较大,正闪峰值时刻和降雹时刻几乎一致,零星地闪分布在强回波外侧35~50 dBZ回波中,≥60 dBZ强回波中并未观测到地闪,鄂东强对流闪电频次较多,以负闪为主,密集的负闪分布在35~55 dBZ强回波区,零星正闪和强回波外围25~35 dBZ层状云对应,以上雷达特征对分类强对流预警都有很好的指示意义。(3)FY-4A闪电成像仪资料LMI、云顶亮温TBB低值区和二维地闪探测位置吻合,LMI总闪和二维地闪随TBB低值中心移动,冰雹和对流性大风的TBB更低,分布在230 K以下,强降水则在250~270 K。
From May 17 to 18,2018,two thunderstorms occurred successively during a continuous severe storm in Hubei.Using data from FY-4A 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-4A 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.
作者
陈仁君
苟阿宁
王玉娟
徐双柱
余蓉
张琴
明绍慧
CHEN Renjun;GOU Aning;WANG Yujuan;XU Shuangzhu;YU Rong;ZHANG Qin;MING Shaohui(Lightning Protection Centre of Hubei,Wuhan 430074,China;Wuhan Central Meteorological Observatory,Wuhan 430074,China;Meteorological Disaster Prevention Technology Center of Qinghai,Xining 810001,China;Zibo Meteorological Bureau,Zibo 255048,China)
出处
《热带气象学报》
CSCD
北大核心
2021年第3期457-467,共11页
Journal of Tropical Meteorology
基金
国家重点研发计划重点专项项目(2017YFC1502000)、湖北省气象局面上项目(2021Y01)、中国气象局预报员专项(CMAYBY2020-081)共同资助。
