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    湖北省分钟级雨强时空分布特征

    Analysis of temporal and spatial distribution characteristics of minute-scale rainfall intensity in Hubei Province

    • 摘要: 利用2019—2022年3—9月湖北省2523个区域站和国家站逐分钟雨量资料,分析了湖北省6 min雨强的时空分布特征及产生极端雨强的大气环流背景。结果表明:全省平均6 min雨强最大值为14 mm,西部山区6 min雨强平均值略小于东部。鄂西南分钟级降水强度较大,但出现频次少,鄂东地区分钟级雨强较大且出现频次较多。3—5月,鄂东南及江汉平原区域为降水高发区,鄂西北虽然分钟级强降水频次不多,但会出现较大6 min雨强(≥12 mm),致灾风险高;6—7月强降水频次明显增多,分布范围较广,雨强≥6 mm高频中心位于鄂东北,与梅雨期低空急流和大别山地形的相互作用有关;8—9月,雨强≥3 mm多发于山区平原过渡带的宜昌、恩施以及大别山南部的黄冈东部。6 min雨强频次分布存在明显日变化,峰值出现在午后至前半夜,以16:00—18:00频次最高,峰值时段对应午后热对流及夜间急流加强时段。月极值雨强出现时高空天气系统可分为三种类型,高空低槽型占一半以上,槽后西北气流型次之,副高型最少。极端分钟级雨强的产生与中小尺度系统的发展演变密切相关。

       

      Abstract: Based on the minute-scale rainfall intensity data of 2523 surface automatic observation stations from March to September in Hubei Province from 2019 to 2022,the spatial and temporal distributions of 6-min rainfall intensity,as well as the synoptic systems of the extreme 6-min rainfall intensity were analyzed.The results show that:the provincial average of the maximum 6-min rainfall intensity is 14 mm,and the average 6-min rainfall in the west is lower than that in the east.The 6-min rainfall intensity in southwest of Hubei is quite large with lower frequency,while the minute-scale rainfall intensity in eastern Hubei is large and with higher frequency.From March to May,the frequency of rainfall in Jianghan Plain and in southeastern Hubei is high,while in northwestern Hubei it is lower but rainfall is large (more than 12 mm),thus leading to a high risk of disaster.From June to July,the frequency of heavy rainfall is obviously higher and more extensive.The high frequency center of rainfall more than 6 mm is located in northeastern Hubei,which is related to the interaction between the low-level jet during Meiyu and the terrain of Dabie Mountains.From August to September,the rainfall more than 3 mm happens more often in Enshi and Yichang located in the transition zone between plain and mountain,and in eastern Huanggang,located south of the Dabie Mountains.The frequency of 6-min rainfall shows obvious diurnal variations,and the high-frequency period occurs from afternoon to midnight,with the peak from 16:00 BT to 18:00 BT.The high frequency period is related to afternoon thermal convection and the nocturnal intensification of the low-level jet.The synoptic systems of maximum 6-min rainfall in each month are divided into three types,with the upper-level trough type occupying more than half,followed by the northwest flow behind the trough type and subtropical high type.Extreme minute-scale precipitation is closely related to the evolution of mesoscale synoptic system.

       

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