Atmospheric precursors for intense summer rainfall over the United Kingdom
Atmospheric precursors for intense summer rainfall over the United Kingdom
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DOI：
10.1002/joc.6431
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发表时间：
2020-01
期刊：
影响因子：
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通讯作者：
R. Allan;S. Blenkinsop;H. Fowler;Adrian J. Champion
中科院分区：
文献类型：
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作者：
R. Allan;S. Blenkinsop;H. Fowler;Adrian J. Champion
强烈的亚日夏季降雨与英国的洪水影响有关。描述降雨事件前的大气条件可以提高对所涉及的大尺度机制的理解。从1979-2014年英国各地的雨量计记录中产生的最强烈的次日降雨强度数据与ERA中期再分析的领域相结合，以表征强降雨事件之前的大气条件。英国6个地区的200个最强烈的3小时事件与1天前英国西部或西南部海平面气压（< - 2 hPa）和200 hPa位势高度（< - 60 m）的负异常有关，西北欧的湿度、蒸发和露点温度高于平均水平。由25个最强降雨事件组成的复合事件的大气前兆更为强烈，但区域间的一致性较差，但在它们发生之前都显示了来自南部或东南部的大量水分输送。最重事件的复合特征为横跨北大西洋的三极位势异常模式。研究发现，纽芬兰上空高于平均位势高度和露点温度，北大西洋低于平均位势高度但蒸发量增加，与5-9天后最强烈的次日降雨事件的几率增加存在微弱关联。
Intense sub‐daily summer rainfall is linked to flooding impacts in the United Kingdom. Characterizing the atmospheric conditions prior to the rainfall event can improve understanding of the large‐scale mechanisms involved. The most intense sub‐daily rainfall intensity data generated from rain gauge records across the United Kingdom over the period 1979–2014 are combined with fields from the ERA Interim reanalysis to characterize atmospheric conditions prior to heavy rainfall events. The 200 most intense 3‐hourly events for six UK regions are associated with negative anomalies in sea level pressure (<−2 hPa) and 200 hPa geopotential height (<−60 m) to the west or south west of the United Kingdom 1 day earlier, with above average moisture, evaporation and dew point temperature over North West Europe. Atmospheric precursors are more intense but less coherent between regions for composites formed of the 25 heaviest rainfall events but all display substantial moisture transport from the south or south east prior to their occurrence. Composites for the heaviest events are characterized by a tripole geopotential anomaly pattern across the North Atlantic. Above average geopotential height and dew point temperature over Newfoundland and below average geopotential height but elevated evaporation in the North Atlantic are found to be weakly associated with an increased chance of the most intense sub‐daily rainfall events 5–9 days later.