摘要
使用宜昌多普勒天气雷达基数据资料,采用统计计算方法,分析了2004—2008年宜昌境内52块强对流云的特征。结果表明:(1)在宜昌地区,产生冰雹的对流云中其平均最大反射率因子均在50 dBz及以上;回波顶高均在9 km以上,最高达到22 km,其中80%的冰雹云的回波顶高在12～16 km之间;最大垂直液态含水量在50 kg.m-2以上的比例为76%;利用回波强度、回波顶高和垂直液态含水量均不能很好地辨别雹云和雷雨云,但可将这些参量作为冰雹发生的参考条件。(2)利用45 dBz回波顶高可较好地识别冰雹云,当强回波高度达到7.6 km时预示有冰雹出现,其临界成功指数达86%。(3)降雹前,强中心回波顶高会出现跃增现象,跃增后不久地面出现降雹,这一特殊现象有助于提前进行冰雹预警。
Based on statistic method,the features of 52 strong convective clouds over Yichang,Hubei province from 2004 to 2008 are analyzed by using the new generation of Doppler weather data.The results show that（1） All convective clouds,which come into hail,have an average maximum reflectivity factor ≥50 dBz,and all the top high of echo are above 9 km,and 80% of the top high of echo of hailstorm clouds are between 12～16 km.There are 76% of hailstorm clouds which the maximum vertical liquid water content is more than 50 kg.m-2 in proportion to all hailstorm clouds.Difference between thunder clouds and hail clouds can＇t be distinguished by intensity of echo,top height of echo and VIL,but the above radar parameters can be taken as the hail occurring reference factors.（2） The hail clouds can be distinguished from strong convective clouds through echo height of the 45 dBz.When the height of the strong echo reaches 7.6 km,the hail will emerge with the 86 percent probability.（3） There is a sudden-increase phenomenon for the echo top of the strong center before a fall of hail,and then the hail appears on the ground shortly after the phenomenon happened.This special phenomenon could be contributed to advance the hail warning.
出处
《暴雨灾害》
2009年第3期261-265,共5页
Torrential Rain and Disasters
关键词
冰雹云
多普勒雷达
识别参量
冰雹预警
Hail cloud
Doppler radar
Identification parameter
Early warning
