2014年7月龙门山脉一次持续性暴雨过程分析

The Analysis of a Persistent Torrential Rainhappened in Longmen Mountain in July 2014

为探讨龙门山脉的持续性暴雨过程成因及非地转湿Q矢量的应用,利用2014年7月18~21日大气环流背景及天气影响系统和NCEP 1°×1°每6 h一次的再分析资料分析,结果表明：500 hP a西太平洋副热带高压外围环流稳定,阻挡西风槽东移使得其持续维持在川西高原,是这次持续性暴雨过程的大气环流背景和影响天气系统。中低层强盛的水汽输送与超级台风＂威马逊＂外围水汽的汇聚作用为这次持续性暴雨过程提供了充沛的水汽条件。暴雨发生前低层非地转湿Q矢量是一个快速增加的过程。暴雨发生时700 hP a非地转湿Q矢量辐合区与强降雨区有较好的对应关系,强降雨中心位于辐合中心东侧到零线梯度的较大处,越接近强降水时间,诊断效果越好;辐合中心与其东侧或南侧的辐散中心构成次级环流圈。同时东北—西南向的龙门山带的陡峭地形引起盆地东南气流的强烈垂直上升运动,对暴雨的增幅有重要作用。

In order to analyze the cause and the use of the convergence of the wet Q-vector of the continuous torrential rain process in the Longmen mountain,the material of atmospheric circulation background,weather impact system and the NCEP reanalysis data（ 1° × 1°） from NCEP / NCAR center on July 18- 21,2014. The results indicate that the stabilization of the environmental field of peripheral of the western pacific subtropical high,mak the upper trough maintain in the Chuanxi plateau the rainstorm’s atmospheric circulation background and affect the weather system. The strong water vapor transport in the lower troposphere combined with vapor transportation of the super typhoon ＂RAMMASUN＂provided abundant water vapor for the continuous torrential rain process. Before the heavy rain,the convergence of the wet Qvector increase rapidly in the lower troposphere. In the heavy rain,the horizontal distribution of the convergence of the wet Q-vector at the level 700 h Pa correspond well with the heavy rainfall center of the same period of time,and the position of maximum rainfall is near the east of the convergence center. The closer it gets to the heavy rain time,the better the diagnosis results. The convergence and divergence center constitute the secondary circulation. The steep northeast to southwest terrain of the Longmen Mountain play a important role in increasing the rainfall that cause the southeast airflow upward motion strongly.