2017-2021年辽宁省冷涡型雷暴大风时空分布及环境参数特征

Characteristics of spatio-temporal distribution and environmental parameters of Cold Vortex thunderstorm gales in Liaoning province from 2017 to 2021

选用2017—2021年辽宁省自动气象站、闪电定位仪、葵花8号卫星和ERA5再分析资料,分析辽宁省雷暴大风的时空分布特征和不同天气系统下雷暴大风发生的环境条件。结果表明:冷涡系统是导致辽宁雷暴大风的最主要天气系统,占全部雷暴大风的62%。冷涡雷暴大风主要集中分布在辽宁中部平原,该区域冷涡引起的雷暴大风占所有雷暴大风的90%。雷暴大风集中出现在5—9月,午后到傍晚出现的次数最多。不同季节雷暴大风发生时的环境条件存在差异,春、秋季雷暴大风对应不同层温差、垂直风切变较强和风暴承载层风速较大等特征;盛夏雷暴大风发生对应水汽条件充沛,近地面蒸发较强、中层干空气侵入和热对流特征明显等。与非冷涡系统相比,冷涡背景下的低空与500 hPa温差和对流有效位能更强,中低层更干燥,垂直风切变和风暴承载层风速更强。冷涡四象限中,雷暴大风常出现在东南和西南象限,占比分别为77.9%和18.5%。两象限雷暴大风对应的环境条件存在差异,东南象限水汽条件更充沛,不稳定程度更强;西南象限中低层更为干燥,地面与500 hPa温差和下沉对流有效位能更大。

Using the data from automatic weather station,lightning locator,FengYun-2G satellite and ERA5 reanalysis data in Liaoning province from 2017 to 2021,the spatial-temporal distribution and environmental conditions of thunderstorm strong wind under different weather systems were analyzed.The results show that the cold vortex system is the most important weather system leading to thunderstorm strong winds in Liaoning province,accounting for 62%of all strong winds.Cold vortex thunderstorm strong winds are mainly concentrated in the central plain of Liaoning province,where cold vortex-induced thunderstorm strong winds account for 90%of all thunderstorm strong winds.Thunderstorm strong winds occur intensively from May to September,most frequently occurring from afternoon to evening.The environmental conditions of different seasonal thunderstorm strong winds vary with seasons.In spring and autumn,the thunderstorm strong winds correspond to stronger temperature differences at various levels,vertical wind shear and storm-bearing wind speeds.In the summer,the thunderstorm strong winds occur corresponding to abundant water vapor conditions,stronger near-surface evaporation,mid-level dry air intrusion and significant thermal convection feature.Compared with non-cold vortex systems,under the cold vortex background,the low-level to 500 hPa temperature difference and storm-bearing wind speeds are greater,the mid-low layer is drier,and the vertical wind shear and convective available potential energy are stronger.Among the four quadrants of the cold vortex,thunderstorm strong winds often occur in the southeast and southwest quadrants,accounting for 77.9%and 18.5%respectively.There are differences in the environmental conditions corresponding to the thunderstorm strong winds in the two quadrants.The southeast quadrant has more abundant water vapor conditions and stronger instability.The mid-low layer is drier in the southwest quadrant,and the temperature difference between surface and 500 hPa and the downdraft convective available potential energy are greater.