2013年7月冀中特大暴雨的中尺度系统特征和环境条件分析

摘要

提利用常规探测资料、NCEP最终分析资料、自动站、FY-2 E卫星以及多普勒雷达资料，分析了2013年7月1日发生在河北中部的大暴雨天气过程。结果表明：（1）河北中部的暴雨天气分为暖区暴雨和切变线暴雨两个阶段，暖区暴雨发生过程中，低层水汽通量辐合急剧增强。（2）非地转湿Q矢量强辐合早于暖区暴雨的发生，其对暖区暴雨有较强的预报能力。非地转湿Q*矢量散度对流凝结加热强迫项大值区在暖区的位置可以用来判断暴雨落区，其在暖区暴雨上空非地转湿Q矢量辐合中发挥了决定性作用。（3）暖区暴雨在地面中尺度涡旋的影响下，由暖区中β中尺度对流云团在初生和发展阶段造成，而切变线对流云团与暖区对流云团合并而成的PECS（持续拉长状中尺度对流系统），配合地面辐合线再次引发强降雨。（4）雷达回波显示β中尺度气旋式流场东南部负速度区中的γ中尺度辐合线为带状强降水多单体风暴持续在四芝兰出现创造了有利的动力条件。%The severe rainstorm process which occurred in the central part of Hebei on 1 July 2013 was ana-lyzed by using the conventional sounding data,NCEP reanalysis data,automatic stations data,FY-2E sat-ellite data and radar data.The results show that:(1 )The rainstorm can be divided into warm sector rain-storm and cold shear rainstorm.During the process of warm sector rainstorm,low-level moisture flux con-vergence was dramatically enhanced.(2 )Strong ageostrophic-wet-Q vector convergence took place before the warm sector rainstorm,and it has good performance in forecasting the warm sector rainstorm.Large value area of ·Q* only with convective condensation heating in warm sector can be used to indicate the heavy rainfall area.Furthermore,condensation heating plays an important role in ageostrophic-wet-Qvec-tor convergence.(3 )Warm sector rainstorm occurred in the developing stage of warm meso-βscale convec-tive clouds,influenced by the surface mesoscale vortex.Then,cold shear convective clouds incorporated with warm sector convective clouds formed PECS,which worked in with the surface convergence line cau-sing rainstorm again.(4)The radar echoes show that meso-γscale convergence lines in the meso-βscale cyclone flow field creates a favorable dynamic condition for banded strong rainfall echo in Sizhilan Area.