2018年7月10日陇南大暴雨成因分析及预报预警方法
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摘要
2018年7月10日陇南市九县区普降大雨,部分地区大暴雨,造成725 918人受灾,直接经济损失35.6亿元。为了预防此类灾害性事件发生造成经济损失和人员伤亡,须在此类灾害事件发生前提早预报,提前预警。通过分析此次大暴雨过程发生时的天气影响系统和物理量特征,找出物理成因。结果显示,"7·10"大暴雨主要影响系统是"东高西低"形势场配置副高西侧的500hPa低槽、700hPa辐合切变线在副高西侧长时间稳定维持;水汽输送路径有3条:孟加拉湾、南海和台湾海峡,降水过程的预报值水汽条件为比湿>12g/kg;低层动力强、上升,中层动力弱、平移,高层200hPa槽后是正值、辐散;陇南的降水模型是在开始降水的1h就达到最大,小流域汇流时间是1～2h,最短时间为40～50min,很容易爆发山洪泥石流灾害。最后总结了预报成功的经验,提出面对此类天气的预报预警方法。
From day to night on July 10 th,2018,there was heavy rain in Jiuxian,Longnan,even downpour in some region,causing 725 918 people were affected,and the direct economic loss was 3.56 billion Yuan.To prevent this kind of disasters and reduce loss and casualties,the disasters should be forecasted and early warned.It analyzes weather influence system and physical quantity feature during the downpour and finds the physical cause.Successful experiences of the forecast was summarized and forecast and earlywarning method in face of such weather was proposed.The main reason of "7·10" downpour is that in the situation field featuring " high east and low west",there is 500 hPa low pressure trough in the west of subtropical high where 700 hPa convergence shear line stays for a long time;there are 3 vapor transport paths that are in the Bay of Bengal,the South China Sea and Taiwan Strait,respectively,and water vapor condition of the prediction value during the rainfall was that the specific humidity is more than 12 g/kg,the lower atmosphere layer has strong driving power and the air flow increases,the intermediate atmosphere layer has weak driving power and the air flow achieves translation and the correction value is after the higher atmosphere layer 200 hPa trough and the air flow diverges;rainfall models in Longnan reaches the maximum value after an hour of the beginning of rainfall.The conflux time of Small Watershed is one to two hours with the shortest time of 40 to 50 minutes,which is likely to trigger debris flow and flush flood disaster.
From day to night on July 10 th,2018,there was heavy rain in Jiuxian,Longnan,even downpour in some region,causing 725 918 people were affected,and the direct economic loss was 3.56 billion Yuan.To prevent this kind of disasters and reduce loss and casualties,the disasters should be forecasted and early warned.It analyzes weather influence system and physical quantity feature during the downpour and finds the physical cause.Successful experiences of the forecast was summarized and forecast and earlywarning method in face of such weather was proposed.The main reason of "7·10" downpour is that in the situation field featuring " high east and low west",there is 500 hPa low pressure trough in the west of subtropical high where 700 hPa convergence shear line stays for a long time;there are 3 vapor transport paths that are in the Bay of Bengal,the South China Sea and Taiwan Strait,respectively,and water vapor condition of the prediction value during the rainfall was that the specific humidity is more than 12 g/kg,the lower atmosphere layer has strong driving power and the air flow increases,the intermediate atmosphere layer has weak driving power and the air flow achieves translation and the correction value is after the higher atmosphere layer 200 hPa trough and the air flow diverges;rainfall models in Longnan reaches the maximum value after an hour of the beginning of rainfall.The conflux time of Small Watershed is one to two hours with the shortest time of 40 to 50 minutes,which is likely to trigger debris flow and flush flood disaster.
引文
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[9]甘璐,郭文利,邓长菊.北京地区两次特大暴雨过程的对比分析[J].干旱气象,2017,35(2):239-249.