锦州地区一次短时局地暴雨V-3θ图特征

利用Micaps 3欧阳位温分析图，运用V-3θ图结构分析法，对2013年7月1-2日锦州东部地区短时局地大暴雨过程进行分析。结果表明：此次锦州地区短时局地暴雨过程是在东北冷涡背景下产生的，通过常规天气学角度预报短时局地暴雨难度较大，V-3θ图结构分析法利用特性层信息的非均匀性和不连续性，反映垂直方向的涡旋运动，可以在一定程度上弥补常规暴雨预报能力的不足。在短时局地暴雨发生之前12-24 h，锦州及其上游地区的V-3θ图有超低温存在；从暴雨开始至暴雨结束，锦州地区逐渐从“顺滚流”转为“逆滚流”；θ、θsed和θ*曲线有多处左倾转为平缓右倾，不稳定能量逐渐减少；水汽条件从有干层侵入至整层湿层，最后转为整层干层，这些特征对锦州地区短时局地暴雨预报有较好的指示意义。分析雷达速度资料可以判断不同高度的风向风速，进而判断“滚流效应”，弥补V-3θ图时空分辨率低的不足；不同下垫面分布可以改变边界层的风向风速，从而影响“滚流效应”，这也是局地暴雨落区预报的重要依据。

Characteristics of a local short-time rainstorm using V-3θ chart method in Jinzhou area

Based on MICAPS3 data, a local short-time severe rainstorm occurred on July 1-2, 2013 in the eastern area of Jinzhou was analyzed using a V-3θ chart method. The results show that this process occurs under the background of northeast cold vortex. In general, it is difficult to forecast a local short-time rainstorm by the conventional synoptic analysis, while a structure analysis method of the V-3θ chart using inhomogeneity and discontinuity of significant pressure layer could reflect vertical motivation of vortex. Thus, it could make up deficiency of conventional rainstorm forecasting. There exists ultra-low temperature on the V-3θ chart in Jinzhou and its upper reaches area before previous 12 to 24 hours of local short-time rainstorm. From the start to the end of this process, tumble is changed from “clockwise” to “anti-clockwise”. Curves of θ, θsed and θ* are changed from left incline in many points to gradual right incline, and instability energy gradually reduces. Water vapor invades from dry layer to wet layer, and then the whole layer changes wet layer. At last, the whole layer becomes dry layer. The above characters mentioned could be of indicative to a local short-time rainstorm in Jinzhou area. Analysis of radar velocity is favorable to judge wind speed and wind direction at different heights, and then judge the “tumble effect”, which can make up shortcomings of low space-time resolution of V-3θ chart. Also, different distribution of underlying surface could change wind speed and wind direction, and further influences "tumble effect”, so this is an important basis for falling area of local short-time rainstorm.