下垫面对渤海西部雷雨大风影响的数值模拟分析

Numerical simulation study of the effect of underlying sea surface on thunderstorm wind in the western Bohai Sea

利用天津WRF中尺度数值预报业务模式系统,对2016年6月10日夜间渤海西部的一次强对流大风过程进行控制预报和敏感性试验预报(渤海到海峡修改为陆地)的对比分析。结果表明:海洋下垫面对渤海前半夜生成的雷雨大风有增强作用,增幅在5~6 m/s。海洋下垫面会使冷池出流边界具有更明显的温度梯度和气压梯度,增幅分别为3℃/经度,2 hPa/经度;海洋下垫面在雷达回波刚入海时对其强度变化没有明显影响,当回波持续一段时间(4 h以上)后,海洋下垫面对回波强度有减弱作用,可能是由于下垫面对近地面风速的增幅作用,使垂直风切变小,回波倾斜度和垂直速度也相应减小造成。

Using the Tianjin Weather Research and Forecasting(TJWRF)numerical prediction system,a sensitivity experiment is conducted for a severe convective storm over the western Bohai Sea on 10 June 2016.The results show that the underlying sea surface intensifies the thunderstorm generated in early night in the Bohai Sea by 5-6 m/s.The underlying sea surface enlarges the pressure and temperature gradient of clod pool outflow boundary by 3℃/Lon and 2 hPa/Lon,respectively.Furthermore,the underlying sea surface shows no significant influence on the intensity of radar echo when it first enters the sea.Nevertheless,the underlying sea surface weakens the intensity of radar echo when it lasts 4 hours or longer,which may due to the decrease of vertical wind shear and the degree of inclination and vertical speed of the radar echo caused by the enhancement of underlying sea surface on near surface wind speed.