垂直积分液态水含量在地面大风预报中的应用

利用天津塘沽的CINRAD-SA型新一代多普勒雷达体扫描垂直积分液态水含量(VIL)产品资料,结合地面大风灾情报告和实况资料,对地面灾害性大风出现前VIL值的演变、发展情况进行了统计分析。结果表明:VIL值达到30kg/m2是地面灾害性大风出现的阈值,VIL值达到或超过40kg/m2则可以看作是大风的一个预警指标;VIL值达到最大后的快速减小意味着将出现地面灾害性大风,VIL值快速减小后的突然跃增则是地面灾害性大风开始的标志。应用评分系统命中率、误警率、临界成功指数检验了上述预警指标,结果表明VIL产品预警地面灾害性大风是可用的,而且随时间调整阈值大小,可以大大提高地面灾害性大风预警的命中率和临界成功指数;地面灾害大风出现前预报员有12～18min的时间用于发布短时、临界大风天气预报和大风预警。

Application of Vertically Integrated Liquid (VIL) Water in Disastrous Wind Nowcasting

Based on the vertically integrated liquid(VIL)water,a statistic analysis of the evolvement and development of VIL before the disastrous winds is made by using the volume scan data of Tianjin CINRAD-SA Doppler weather radar in combination with the reports of disastrous wind and observational data.The results show that a VIL value of 30 kg/m2 can be regarded as the threshold of disastrous winds and 40 kg/m2 as the forecasting index.The rapid decreasing VIL after the maximum indicates the beginning of disastrous winds,and the subsequent jumping change can be acted as the symbol of the beginning of disastrous winds.The verification suggests that these warning indexes are not only practicable but also adjustable with time.Before the beginning of disastrous winds,forecasters have 12 to 18 minutes to issue short-time,nowcasting weather forecast.