晴空湍流在强天气过程临近预报中的应用研究

为研究强对流天气发生前的先兆信息,利用多普勒天气雷达的径向风场与谱宽数据对大气的湍能耗散率进行了反演。通过对2009年6月3日南京一次强雷暴过程和2009年6月14日南京一次飑线过程的研究发现,天气过程发生前湍能耗散率随时间的变化,可以用来判断湍流运动的剧烈程度。强对流天气发生前往往会有晴空回波的出现;并且湍流运动较正常情况下剧烈。反演得到的边界层湍能耗散率可以用来识别较强的湍流运动。通过两次典型的强天气过程的对比分析还发现,湍流在降水过程发生前2~3 h,会有趋势变化的拐点出现;并且是一个持续的加强阶段。当趋势特征出现后,且湍能耗散率最大量级达到3 000 cm2·s-3以上时,可认为即将有强对流的天气过程出现。根据湍能耗散率的变化可以获得强对流天气出现的先兆信息,这对提高强对流天气的预报水平具有重要意义。

Study of Clear-air turbulence to the Nowcasting Forecast of Severe Convective Weather

To study the precursor information of severe weather, the radial wind field and spectrum width data of Doppler weather radar data are utilized to retrieve the turbulent energy dissipation rate of clear-air echo. Studying two strong convective weather process occurred in Nanjing in June 2009 3rd and June 14th 2009 shows that: time measured turbulent energy dissipation rate can be used to estimate the severity of turbulence . There are always clear-air echo in low levels before convective weather, turbulent motion in low layers intensify drastically. The retrieved turbulent energy dissipation rate can be used to recognize the strong turbulence flow, the comparison of two convective weather also shows: 2 or 3 hours before the convective weather, the time measured turbulent To study the precursor information of severe weather, the radial wind field and spectrum width data of Doppler weather radar data are utilized to retrieve the turbulent energy dissipation rate of clear-air echo. Studying two strong convective weather process occurred in Nanjing in June 2009 3rd and June 14th 2009 shows that: time measured turbulent energy dissipation rate can be used to estimate the severity of turbulence . There are always clear-air echo in low levels before convective weather, turbulent motion in low layers intensify drastically. The retrieved turbulent energy dissipation rate can be used to recognize the strong turbulence flow, the comparison of two convective weather also shows: 2 or 3 hours before the convective weather, the time measured turbulent energy dissipation rate curve appears a turning point. With the appearance of tendency and the maximum level of turbulent energy dissipation rate reaching 3000cm2?s-3,can the convective weather process be regarded appearing in the soon future. The indication of convective weather will be obtained with the variation of turbulent energy dissipation rate, thus making significant sense to the forecast of strong convective weather.