2016年大连地区强对流天气雷达回波特征分析.doc

2016年大连地区强对流天气雷达回波特征分析
摘要:该文利用探空资料、加密自动站资料、天气雷达资料对2016年6―9月大连地区9次强对流天气过程,即短时强降雨(4次)、雷暴大风(3次)和冰雹(2次)3种强对流类型进行了雷达回波特征分析。结果表明:探空资料中K指数适用于短时强降雨识别;CAPE值与探空距离强对流时间密切相关;较大的高低层的温差有利于识别雷暴大风和冰雹;较低的0℃层和-20℃层高度有利于冰雹判别;较大的0~6km深层垂直风切变有利于雷暴大风识别。最大回波强度和所在高度,短时强降雨小于雷暴大风和冰雹;弓状型雷暴大风相对于低仰角径向速度大值区类型的雷暴大风有更长的预警时间提前量;雷暴大风和冰雹的VIL值都相对较大,不利于区分两者。研究结果为大连地区强对流预报预警提供参考依据。
关键词:大连地区;雷达回波特征;强对流天气预警
中图分类号 文献标识码 A 文章编号 1007-7731(2017)10-0156-06
Abstract:This paper examines 9 convection events occurred during June and September 2016 in Dalian area by using sounding,densely-covered automated weather station and weather radar data. 9 convection cases are categorized into 3 types:short-range strong precipitation (4 cases);thunder induced damaging wind (3 cases) and hail (2 cases). The results indicate:K index is an usful indicator for short-range strong precipitation;CAPE is closely related to the difference between souding time and convection initiation time;Large difference between mid-level and low-level temperature is an indication for thunder induced damaging wind and hail development;Relatively low 0℃ and-20℃ heights are indicative for hail and large wind shear of 0~6km is indicative for thunder induced damaging wind. For maximum reflectivity and its height,short-range strong precipitation is slightly smaller than damaging wind and hail. Early warning of Bow-shape-echo damaging wind is more viable than that of strong radial velocity at low elevation. In both damaging wind and hail cases,large VIL values are observed,as a results,it can not be used to distinguish the two convection types. The results provide guidance for convection warning for Dalian area.
Key words:Dalian area;Weather radar echo features;Severe weather warning
??对流天气[1]是指由对流风暴产生的短时强降雨、雷暴大风、冰雹、龙卷等中小尺度的灾害性天气现象。大连地区的强对流天气绝大部分发生在6―9月,其特点是突发性强,持续时间短,局地性强,易致灾。孙继松等[2]认为热力不稳定层结分析只有在对流发生前才有意义。另外,CAPE值不仅决定了对流云的发展高度,一定程度上也最终决定了强对流中雨滴或雹粒的大小和密度。雷蕾等[3]利用探空资料研究发现,CAPE和K指数可以判断是否出现强对流天气,但是不能判别强对流天气种类。北京地区雹暴要求环境大气的0℃层和-20℃层高