【摘要】 利用天气观测资料和NCEP再分析资料对2004—2013年5—9月影响山东的切变线天气特征和环流形势进行了分析。将影响山东的切变线按热力性质分为冷切变线和暖切变线,10 a间影响山东的切变线共发生59次,其中暖切变线出现43次,占切变线总发生次数73%;冷切变线出现16次,占切变线总发生次数27%。切变线发生频数7月最多,6月次之,分别占切变线总数的35.6%和23.7%,9月最少,约占0.05%。影响山东典型切变线的发生与副高关系密切,冷切变线多出现在西风槽东移受阻,在对流层低层逐渐形成,暖切变线则出现在西风带小高压与副高合并,副高北抬时形成。针对2次典型冷暖切变线暴雨天气过程对比分析其暴雨落区、雷达回波特征和动力机制等,结果发现:暖切变线降水的强度、暴雨范围和持续时间明显大于冷切变线降水。暖切变线暴雨的GPS可降水量在强降雨出现前8 h快速上升,可降水量峰值对应地面降雨大值,对地面降雨变化反映不敏感,物理量呈垂直分布,强回波单体基本位于暖切变线雨带的中间。冷切变线暴雨的GPS可降水量短时间内增幅大,地面强降雨在峰值出现1 h后发生,对地面降雨变化反映较敏感,物理量从低层到高层向北倾斜且上升运动区较深厚,回波单体位于切变线南侧。更多还原

【Abstract】 This paper analyses the weather characteristics and circulation situation of shear line by using the meteorological observations and NCEP reanalysis data,which influences Shandong from May to September 2004-2013. The shear line occurred 59 times in Shandong Province in the past 10 years,the shear line in Shandong was divided into the cold one and the warm one based on its thermal properties. Among them,the warm shear line has 43 times,which accounts for 73% of the total number,the cold shear line occurred 16 times,which accounts for 35.6% of the total,The frequency of shear line occurred in July is the second in June,accounting for 35.6% and 23.7% of the total shear line respectively,and in September it is about 0.05%. The occurrence of typical shear line in Shandong is closely related to the subtropical high-pressure. The cold shear line gradually forms in the lower troposphere when the eastward-moving west wind trough is blocked. The warm shear line appears when the subtropical high-pressure is lifted north and small high-pressure of subtropical westerlies combines with the subtropical high-pressure. By analyzing the rainstorm area,radar echo feature and dynamic mechanism of two typical rainstorm processes caused by cold shear line and warm shear line,the results are follows: The warm shear line precipitation shows stronger influence than that of cold shear line in the intensity,rainstorm range and duration of precipitation. The GPS precipitation of the warm shear line rainstorm rises rapidly 8 hours before the occurrence of heavy rainfall. The peak values of precipitation correspond to the large values of the surface rainfall,which is insensitive to the change of the surface rainfall. Its physical quantity shows vertical distribution. The GPS precipitation of the cold shear line rainstorm could rapidly increase in a short period of time and the ground precipitation reaches the peak one hour later,which indicates the GPS precipitation of the cold shear line rainstorm is sensitive to the ground precipitation. The physical quantities show the northward inclination from the lower layer to the upper layer and the ascending movement area is deeply. The echo monomer is located over the south side of the shear line.更多还原