锋面短时强降水系统发展模态的环境因子浅析

Analysis of environmental characteristics affecting the evolution pattern of the frontal short-time heavy rainfall system

利用探空和地面加密自动站逐小时观测资料,对2010-2011年汛期发生在锋面上的四次具有不同发展模态的短时强降水过程的降水系统环境场特征进行了分析。结果表明:对于产生短时强降水的中尺度对流系统(MCS),地面假相当位温(θse)等值线密集区和地面切变线的分布形态及运动是影响其系统模态发展和移动方向的关键因素,且对流单体的新生还与地面辐合区密切相关。纬向型MCS的θse等值线密集区呈纬向分布;经向型MCS的θse等值线密集区呈经向分布;转向型MCS的θse等值线密集区则由经向转为纬向分布。不同发展模态MCS的强降水持续时间与地面θse高值区的持续时间关系密切。

Using sounding and hourly data at ground automatic weather stations, the environmental field characteristics of four frontal short-time heavy rainfall events with different evolution patterns occurred in the prevailing period of Meiyu front in eastern China from 2010 to 2011 are analyzed. The results show that the evolution pattern and moving direction of MCSs are closely related to the distribution and motion of the dense isoline region of ground pseudo-equivalent temperature, and the formation of convective cells is relative to the ground convergence region. The dense isoline region of pseudo-equivalent potential temperature in the zonal, meridional and turning pattern of MCSs is in zonal, meridional and turning(from zonal to meridional) distribution, respectively. Moreover, the high value area of ground pseudo-equivalent temperature has a close relationship with the duration of heavy rainfall in different evolution patterns of MCSs.