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    2017—2021年冷涡背景下辽宁短时强降水时空分布及环境参数特征

    The spatiotemporal distribution and environmental parameter characteristics of short-duration heavy rain in Liaoning under the background of Cold Vortex from 2017 to 2021

    • 摘要: 利用2017—2021年辽宁省自动气象站小时降水和ERA5再分析资料,筛选冷涡背景下小时降水量不低于20 mm的短时强降水样本,根据短时强降水站点和500 hPa冷涡位势高度中心的位置,将辽宁冷涡短时强降水划分为不同象限,对比了冷涡不同象限内短时强降水的观测特征和形成条件。结果表明:辽宁冷涡短时强降水发生时冷涡中心最多出现在110°~124°E、48°~58°N。冷涡短时强降水占所有短时强降水的35.7%,处于冷涡不同象限短时强降水占比从大到小依次为东南、西南、东北和西北象限。小时降水量大、影响范围大的短时强降水主要集中在冷涡的东南和西南象限。辽宁中北部为短时强降水高发区,其中东南象限短时强降水占主导的站点覆盖辽河流域和沿海区域,西南象限的短时强降水则集中分布在辽宁北部。两种象限短时强降水环境条件的相同点是温湿廓线更加接近、各高度层的对流有效位能为连续正值和有利于形成风垂直切变的风场特征,不同之处在于东南象限短时强降水常发生在更暖湿的环境中,并具有更强的垂直风切变,更有利于出现强度更强、范围更大的短时强降水。西南象限短时强降水则发生在水汽偏干、强静力不稳定和近地面相对湿度更低的环境中,因此更有利于同时出现多种强对流天气。

       

      Abstract: Based on hourly precipitation data from automatic weather stations in Liaoning Province and ERA5 reanalysis data from 2017 to 2021,the short-duration heavy rain (CV_SDHR) with hourly rainfall no less than 20 mm under the background of the Cold Vortex (CV) was selected and divided into different quadrants based on the relative position of the automatic weather stations and the 500 hPa potential height center of the CV.The highest occurrence frequency of CV centers lies between the eastern Inner Mongolia (110°~124°E) and the northern Heilongjiang(48°N),up to 58°N when CV_SDHR occurs.The spatiotemporal distribution and environmental parameter characteristics of SDHR in different quadrants were compared.The results show that CV_SDHR accounts for 35.7% of the total SDHR.The proportion of CV_SDHR in different quadrants decreases in the following order:southeast (SE_SDHR),southwest (SW_SDHR),northeast,and northwest quadrants.CV_SDHR with large hourly rainfall and wide impact range is mainly concentrated in the southeast and southwest quadrants of CV.The central and northern parts of Liaoning is a high-risk area for CV_SDHR.The stations dominated by SE_SDHR cover the Liaohe River Basin and coastal areas,while the stations dominated by SW_SDHR are concentrated in northern part of Liaoning.CV_SDHR exhibits monthly and daily variation characteristics with unimodal distribution.It mainly appears in the afternoon to evening from July to August,but with variations in different quadrants regarding the peak proportion,occurrence time,and duration.The similarity of CV_SDHR in different quadrants is that the temperature and humidity profiles are closer,the CAPE is narrower,and the wind field is conducive to the formation of vertical wind shear.The difference is that SE_SDHR often occurs in warmer and wetter environments,and has stronger and vertical wind shear,which is more conducive to the occurrence of stronger and larger range of CV_SDHR.The SW_SDHR appears in environments with dry water vapor,strong static instability,and lower relative humidity near the ground,making it more conducive to the simultaneous occurrence of multiple severe convective weathers.

       

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