中文摘要：

使用水平分辨率20km的RSM—RANAL再分析资料和WRF模式，对2004年7月12日影响上海地区的一次飑线过程进行分析和数值模拟，结果表明：（1）雷暴发生区域的西北侧约300krn处有一冷锋，地面风场辐合；中低层为一致西南急流，雷暴发生区域上空300hPa位于西风急流右后侧辐散区中；地面存在明显的温度梯度。（2）雷暴发生前浙皖交界山区处的CAPE增至1000J／kg，CIN减至30J／kg以下；杭州湾附近的CAPE值大于2000J／kg。这些地方之后均有强对流单体生成，并成为飑线的一部分。（3）WRF模式对这次飑线过程的主要特征模拟较好，包括地面风场和飑线的结构。（4）敏感性试验指出陆面过程对本次飑线过程的形成发展起了重要作用。一方面通过潜热通量输送增大边界层湿度；另一方面通过感热通量输送改变了边界层的层结结构，使得低层辐合（或抬升）比较容易释放不稳定。在强对流天气的预报中地表条件不可忽略。

英文摘要：

Analysis and a numerical simulation study are carried out to investigate the effects of surface fluxes on the development of a long-lived severe squall line that occurred on 12 July 2004 near Shanghai using the RSM-RANAL re-analysis data and WRF model. Results reveal that： （1） The squall line occurred in the warm sector ahead of a cold front, and the environment was characterized by a low-level jet, upper-level divergence, squall line and well-defined temperature gradient. （2） At 0600 UTC on 12 July 2004, Convectively Available Potential Energy （CAPE） enhanced to more than 1 000 J/kg and Convective Inhibition （CIN） reduced to less than 30 J/kg at a mountainous area joining Zhejiang with Anhui provinces. （3） The squall line, including surface wind and squall line structure, is simulated well by the WRF model. （4） The sensitivity experiment shows that the squall line cannot happen if there is no surface flux. The surface fluxes moistened the boundary layer atmosphere and made it more unstable and thus more favorable for the convection to develop. Surface conditions cannot be ignored in the forecast of severe convective weather.