2016年洛阳一次区域暴雨天气成因分析

利用常规气象观测资料、NCEP1°×1°的逐6h再分析资料及雷达产品等资料,对2016年7月18-19日洛阳地区的一次区域性暴雨天气过程的大尺度环流特征、物理量及其雷达回波特征等进行了诊断分析.结果表明,西风带低槽、中低层低涡和切变线、地面暖倒槽是造成此次暴雨的主要天气系统.此次暴雨第1阶段前期以对流性降水为主,后期以混合性降水为主,具有较强的条件不稳定,而且水汽条件充沛,地形和低层偏东风的作用是造成此阶段强降水的主要原因;第2阶段是以层状云降水为主的混合性强降水,在大片的层状云降水区中,有对流雨团的发展,这些对流雨团的缓慢移动和较长的持续时间是此阶段强降水的重要原因.在强降水发生时段内,低层东南急流出口区左侧的辐合区,高空的分流区及地面暖倒槽的东移北抬,为暴雨的产生提供了有利的动力条件.地形的抬升和阻挡作用是第1阶段前期对流性强降水产生的主要原因之一.低层的西南气流和东南气流2条水汽通道的维持,为暴雨的产生提供了充足的水汽.

Analysis of the Causes of a Regional Rainstorm in Luoyang in 2016

Based on the conventional meteorological observation data,the 6 h reanalysis data of NCEP 1° × 1° and the radar products,the largescale circulation characteristics,physical quantities and radar echo characteristics of a regional rainstorm process in Luoyang area from 18 to 19 in July 2016 were analyzed.The results showed that the westerly low trough,the low vortex and shear line at low and middle levels,and the ground inverted trough were the main synoptic systems.The rainstorm process was divided into two major stages.In the first stage,it was severe convective precipitation earlier and later turned to mixed severe precipitation.The conditional instability was strong and water vapor was abundant.The terrain and easterly wind at low level were the main reasons for the heavy rain at this stage.In the second stage,it was a mixed precipitation with stratiform cloud precipitation.In the large stratus precipitation area,the convective rain clusters developed.The low movement of these convective rain clusters and the longer duration were important causes of heavy rain at this stage.During the heavy rain process,the convergence area on the left side of the export area of the southeast jet at low level,the diverging area at high level and the northeastern movement of the warm inverted trough provided a favorable driving force condition for the heavy rain.The topographic lifting and blocking was one of the main causes of severe convective precipitation in the first stage.The maintenance of two water vapor channels form southwest and southeast provided adequate water vapor for the heavy rain.