辽宁省短时暴雨和大暴雨时空分布与变化特征

采用中国气象局发布的“暴雨橙色、红色预警信号”定义，分别定义短时暴雨和短时大暴雨。利用辽宁2010—2018年5—10月1587个自动站逐时降水资料，统计分析短时暴雨、大暴雨空间分布特征和多尺度时间特征，从而得到短时暴雨、大暴雨的高发区、易发时段，并做简单天气学判断。结果表明：短时大暴雨高发区域位于辽宁东南沿海地区，可能是东北冷涡与北上气旋、西太平洋副热带高压等相互配合，导致辽宁省沿海地区易出现强度大、范围广和持续时间长的暴雨天气过程有重要关系；短时暴雨、大暴雨旬变化呈现“凸”字形结构，短时暴雨从5月上旬至10月上旬都可能发生，呈现单峰型特征。短时大暴雨显著增强从7月上旬开始，8月下旬后短时大暴雨急剧减少。短时暴雨、大暴雨日变化均呈现“两峰一谷”特征。短时暴雨以夜雨居多，可能与夜间西南急流加强有关。短时暴雨00—08时高发区域最为密集，活跃地区为阜新—朝阳、抚顺—盘锦—葫芦岛和辽宁东南部。短时大暴雨00—08时高发地区为辽宁西部、东部和东南部。

Spatiotemporal characteristics of the short-term rainstorm and heavy rainstorm events in Liaoning province

Based on hourly precipitation data at 1587 automatic weather stations in Liaoning province from May to October during 2010-2018,we identified short-term rainstorm and heavy rainstorm events according to the standards of orange and red rainstorm warning signals issued by China Meteorological Administration.The spatial distribution and multi-scale temporal variations of the short-term rainstorm and heavy rainstorm were analyzed to obtain high-incidence areas and periods after synoptic analysis.The results showed that high-incidence areas of short-term heavy rainstorm events are distributed in the southeastern coastland of Liaoning province.The mutual effects of weather systems such as cold vortex in Northeast China,cyclone moving to the north,and subtropical high in the western Pacific probably result in the frequent occurrence of heavy and persistent rainstorm events over wide areas.The ten-day variations of day numbers of the short-term rainstorm and heavy rainstorm exhibit a "convex" shape,with a single peak between early May to early October.The occurrence frequency of heavy rainstorm significantly increase after early July and decrease sharply after late August.The diurnal variations of rainstorm and heavy rainstorm events exhibit the "two peaks and one valley" pattern.Rainstorm events mostly occur at night,which is probably due to the strengthening of southwestern jets.The highest occurrence frequency of short-term rainstorm occurs from 00:00 to 08:00 Local Standard Time (LST),especially in areas of Fuxin-Chaoyang,Fushun-Panjin-Huludao,and the southeastern Liaoning province.The high-incidence areas of short-term heavy rainstorm between 00:00 and 08:00 LST include the western,eastern and southeastern parts of Liaoning province.