安顺市2015-2019年冰雹时空分布特征及雷达临近预警指标研究

Study on the Spatial-temporal Distribution Characteristics of Hail and the Radar Approaching Warning Indicators in Anshun City from 2015 To 2019

利用安顺市2015-2019年降雹个例、MICAPS常规观测资料以及贵阳雷达资料,分析总结了安顺市冰雹时空分布特征及雷达临近预警指标。结果表明:安顺市冰雹以直径20 mm以下的小冰雹为主,冰雹站次呈北多南少特征;冰雹天气主要发生在春季,4月最多,5月次之;2015-2019年期间,2019年安顺市冰雹站次最多,2017年最少。直径10 mm以上与直径10 mm以下冰雹对应的雹云相比,其强回波值更强、降雹概率更高、强回波中心平均升降次数更多、上升幅度及最高上升高度更高(须在0℃层高度以上)、对应的径向速度特征(辐合/辐散、旋转)出现时间较降雹时间提前量更多,45 dBz回波均上升至-20℃层高度以上。而直径10 mm以下冰雹对应的雹云,45 dBz回波均上升至0℃层高度以上,但上升至-20℃层高度的仅15%。此外,强回波中心上升高度(0℃层高度以上)越高,冰雹直径越大。以上雷达回波特征均可作为安顺市冰雹预警指标,有利于提高安顺市冰雹预警准确率及提前量。

The spatial-temporal characteristics of hail and the radar approaching warning indicators were analyzed using the hail cases in Anshun City from 2015 to 2019,MICAPS conventional observation data and the Guiyang radar data.The results show that the hail in Anshun was mainly small hail with a diameter of less than 20 mm,the number of hail stations was more in the north than in the south.The hail weather mainly occured in spring,with the most frequent occurrence in April,followed by May.The number of hail stations in Anshun was the most in 2019 and the least in 2017 from 2015 to 2019.For the corresponding hail clouds with a hail diameter of more than 10 mm,compared with those with a hail diameter of less than 10 mm,its strong echo value was stronger,hail probability was higher,the average lifting times of strong echo center was more,the rise range and the highest rise height were higher(must be above 0℃layer height),and the occurrence time of radial velocity characteristics(convergence/divergence and rotation)was more advanced than that of hail falling time,the echoes of 45 dBz all rose above-20℃layer height,while the hail clouds with a hail diameter of less than 10 mm,the echoes of 45 dBz all rose above 0℃layer height,but only 15%of them reached-20℃layer height.In addition,the higher the height of strong echo center(above 0℃layer height),the larger the diameter of hail.The above radar echo features could be used as hail warning indicators in Anshun city,which was conducive to improving hail warning accuracy and advance quantity in Anshun City.