天津地区080625强对流天气过程的分析

The analysis of a strong convective precipitation process in Tianjin on 25 June 2008

强对流降水是天津地区重要的灾害性天气,为了研究该类天气发生发展的动力学、热力学机制,利用NCEP/NCAR再分析资料和FY-2C卫星逐时TBB资料对2008年6月25日天津的强对流降水过程进行研究,然后利用WRF(weather research and forecasting)中尺度数值模式对该次强对流降水过程进行数值模拟和诊断分析。结果表明:中尺度露点锋是该次强对流降水的重要机制,其对应的低层气流辐合所形成的强烈上升运动及相对应的强烈发展的对流云团,是此次天津强对流降水的直接影响系统;对流有效位能等参数的变化非常好地反映出此次强降水天气的发生和发展特征;较大的相对螺旋度与此次强对流天气的发生对应也较好。由此认为,中尺度露点锋锋生的动力学、热力学过程是此次强对流降水天气发生发展的重要机制。

The strong convective precipitation is one of disastrous weathers in Tianjin area.Based on the NCEP/NCAR reanalysis data and FY-2C TBB data,a heavy rainfall process in Tianjin area on 25 June 2008 is analyzed and simulated by the WRF（weather research and forecasting） model.The high spatial-temporal resolution data from model output are used to analyze the process.Results show that the movement of mesoscale dew-point front might be an important mechanism for the strong convective precipitation process.The low-level convergence airflow plays a crucial role in the formation and development of mesoscale convective clouds,which is the directly influencing system of the heavy rainfall process.CAPE（convective available potential energy） and another thermodynamical parameter can perfectly reflect the formation and development of the heavy rain process.It is found that the heavy rainstorm area has a better corresponding to higher storm relative helicity（SRH）.The frontogenesis of mesoscale dew-point front is the most important mechanism of the strong convective precipitation.