山东西北部两次局地大暴雨过程对比分析

Comparative Analysis of Two Local Heavy Rains in Northwestern Shandong

[目的]对比分析山东西北部2次局地大暴雨过程。[方法]利用自动站观测资料、探空资料及NCEP再分析资料,从环流形势、影响系统和物理量场方面,对2010年7月18日夜间和8月9日夜间发生在山东西北部地区的2次局地大暴雨天气过程进行对比分析,探讨山东局地大暴雨的内部结构以及形成的可能机理。[结果]这2次暴雨均产生在500 hPa槽前西南气流的前部,在850 hPa附近的锋区中,大气均有较强的斜压性;2次暴雨均发生在低层有西南暖湿气流和850 hPa有切变线影响下,θse高能舌后部的密集区内常是暴雨易发地带,暴雨区与垂直速度大值区有较好的对应。不同点是:前次暴雨过程,700 hPa有明显的西南风低空急流与切变线,大降水区主要为700 hPa暖切南部地区;而在后次暴雨过程中,没有明显的西南风低空急流与切变线,大降水区处于两高之间。[结论]该研究为今后此类暴雨的预报提供有价值的思路。

[Objective] The aim was to comparatively analysis two local heavy rains in northwestern Shandong Province.[Method] By using observation data from automatic weather station,sounding data and NCEP reanalysis data,two local heavy rains at night on July 18 and August 9 in 2010 in northwestern Shandong was comparatively analyzed from the aspects of circulation situation,influence system and physical field,and the internal structure and possible formation mechanism of local heavy rain in Shandong were discussed further.[Result] The two heavy rains occurred in the forepart of southwest air in front of 500 hPa trough,and there was stronger atmospheric baroclinicity in front zone near 850 hPa.The two heavy rains were affected by southwest warm and humid airflow at low level and shear line at 850 hPa;heavy rain often appeared in intensive area behind high energy tongue,and heavy rain area corresponded with the area with high vertical speed.From the differences,during the previous heavy rain process,there was obvious southwest low level jet and shear line at 700 hPa,and the area with large precipitation was located in the south of warm shear line at 700 hPa;during the latter heavy rain process,there was no obvious southwest low level jet and shear line,and the area with large precipitation was between two high presures.[Conclusion] The study could provide valuable thinking for the forecast for this kind of rainstorm in the further.