辽宁省东南部一次暴雨过程动力诊断分析

Dynamic Diagnosis Analysis of a Rainstorm Process in the Southeast of Liaoning Province

[目的]对2015年8月2-4日辽宁东南部地区一次由东北冷涡引起的大范围持续性暴雨过程进行动力诊断分析。[方法]采用FNL一日4次再分析资料,分辨率为1°×1°,结合Micaps格式地面、高空观测资料,分析2015年8月2-4日辽宁东南部地区一次持续性暴雨过程的降水实况、环流背景和动力条件。[结果]东北地区上空有深厚低压系统,东侧阻塞高压和南侧副热带高压阻止其东移南压;暴雨发生地区位于强盛的低空急流出口左侧区域、高空急流入口区的右侧,低空急流促使底层风场切变辐合,高空急流使得高空存在一个明显的＂抽吸＂作用;低空辐合、高空辐散的散度场分布有利于空气的上升运动;暴雨发生地区存在广义湿位涡正异常区,且广义湿位涡正异常区域与未来6 h暴雨区域及暴雨强度有良好的对应关系。[结论]该研究为暴雨预报提供指示性因子。

[Objective] The research aimed to analyze the dynamic conditions of a big range sustained rainstorm process caused by northeast cold vortex in Liaoning Province southeast from August 2 to August 4 in 2015. [Method]Using FNL 1° × 1° data and Micaps ground and high observational data,the precipitation,circulation background and dynamic conditions of a sustained rainstorm process in Liaoning Province southeast on August 2-4,2015 were analyzed. [Result]There was a deep and low pressure system over Northeast China during the storm,on the east side of the south subtropical high blocking high pressure and prevent its eastward and southward. The area of heavy rainfall was located in the left area of the strong low level jet stream and in the right side of the entrance area of upper jet stream. Low level jet wind shear convergence to the bottom,the upper jet stream made a clear suction effect. Low altitude convergence and divergence distribution was conducive to air upward movement. There was a broad area of wet potential vorticity in the heavy rain area,and the area of the positive anomaly area of the generalized moist potential vorticity had a good correspondence with the intensity of the rainstorm area and the heavy rain in the next 6 hours.[Conclusion]The study provides indicative factor for the heavy rain forecast.