070703天长超级单体龙卷的多普勒雷达典型特征

Doppler Weather Radar Typical Characteristics of the 3 July 2007 Tianchang Supercell Tornado

主要使用南京多普勒天气雷达资料,分析了2007年7月3日发生在安徽天长和江苏高邮的龙卷风天气,着重分析了中气旋和龙卷涡旋特征(TVS)等产品的典型特征。龙卷发生在飑线回波带的北端强烈发展的超级风暴单体中,回波带前沿存在强烈的水平风切变,使得回波带上不断有中气旋生成。对产生龙卷的超级风暴单体,龙卷发生30min前,雷达给出了中气旋(M)产品,该中气旋持续了7个体扫的时间(42min),在中气旋出现后第5个体扫,雷达给出龙卷涡旋特征(TVS)产品,龙卷涡旋特征持续了3个体扫,综合切变产品也给出了显著的提醒。实地调查结果,龙卷风和第2个TVS同时发生,龙卷风位置与TVS位置对应,但位于TVS的南侧,位于中气旋最大风速圈的南缘。虽然CINRAD/SA雷达的TVS产品有虚警的情况,但结合反射率因子、平均径向速度、中气旋、综合切变等产品的分析,对于龙卷监测和预警会很有帮助的。

Using the data of Nanjing Doppler weather radar （WSR98D）, the tornado occurrin g in Tianchang of Anhui Province and Gaoyou of Jiangsu Province on July 3, 2007 was analyzed. The characteristics such as mesocyclone （M） and tornadic vortex s ignature （TVS） were found.The tornado occurred in the strong development supercell located on the north of line echo wave pattern （LEWP）, the strong shear of wind direction existed in the front of echo line, and it makes the mesocyclone continuously generated along the echo line. In the cell tornado, mesocyclone （M） products can be worked out 30 min before tornado occurrence, the M lasts for 7 volume scan time lengths （42 minutes）, thus TVS products can be worked out at the 5th volume scan of M product appearance, it lasts 3 volume scans, and the combined shear products have also given out notable prompting. According to the field survey, the tornado occurred at the time that the 2nd TVS occurred, it is located on the south side of the TVS, and consistent with the southern fringe of mesocyclone. Although the TVS products may be false at time, but with the checking of reflectivity, the base radial velocity, mesocyclone, combined shear products etc., it is useful for making tornado warning.