承德市一次西北涡暴雨成因分析

A comprehensive analysis for Northwest Vortex Rainstorm

文章利用常规气象观测资料和NECP再分析资料,对2013年7月1日河北省东部的暴雨与大暴雨过程进行分析。结果表明：（1）高纬阻塞形势维持,有利于青海地区西北涡生成,西北涡沿着副热带高压外围引导气流向东北方向移动时,暴雨落区与对应的地面倒槽北部象限的路径非常一致;（2）雷达回波的＂列车效应＂、逆风区以及卫星云图上MCS的小断过境是导致承德南部降水较大的主要原因;（3）凝结函数、比湿的垂直分布与移动,对于大气湿层厚度的变化具有很好的指示作用：（4）高低空急流的有利配置以及燕山迎风坡的空气质量堆积引发的斜升气流为强降水天气的发生提供了动力条件;（5）∑θse（500、700、850hPa）的梯度大值区持续维持在承德市南部上空为暴雨天气提供了充沛的能量条件;（6）欧阳位温曲线在对流层顶存在明显的超低温层,为提前6-12h预报暴雨天气提供了重要依据。

In this paper,based on the conventional meteorological observation data and NECP reanalysis data analyse the torrential rain and rainstorm process in eastern hebei Procince.Analysis found that（l）Maintain of blocking situation in high latitude in favor of the formation of northwest vortex in Qinghai area,when the northwest vortex moving to the northeast along leading airflow around the subtropical high,the path of the area of torrential rain and North quadrant of inverted trough are consistent;（2） The ＂train effect＂ and the upwind in radar echo,crossing of MCS in satellite image is the main reason that much heavy rain appeared in southern Chende;（3）The vertical distribution and movement of condensation function have a good indicator for the change of the thickness of atmospheric humidity layer,（4） Obliquely ascending airflow triggered by favorable configuration of the high and low-level jet and air packing in Yanshan windward supply sufficient dynamic conditions for the occurrence of strong rainfall weather,（5） Gradient values of∑θse（5＋7＋8） sustain over the southern Chende provides sufficient energy condition for rainstorm weather;（6） Curve of OYANG potential temperature in tropopause exist ultra low temperaturelayer.which provides an important basis for 6-12 hours in advance to forecast rainstorm weather.