【摘要】 选用大连市和丹东市SA多普勒天气雷达资料，结合地面观测和ERA5再分析资料，对比分析2020年9月11日(过程Ⅰ)和2021年9月10日(过程Ⅱ)辽东半岛两次微湿下击暴流天气过程的环流背景及成因。结果表明：两次过程均发生在东北冷涡背景下，过程Ⅰ为北上台风变性后的冷涡，过程Ⅱ为切断低压。两次过程的大气层结均为“上干下湿”的不稳定层结，探空曲线呈向上开口喇叭型，近地面温度垂直递减率接近干绝热，整层大气可降水量大于30 mm,抬升凝结高度较低，CAPE和DCAPE较小；0～6 km风切变强度为过程Ⅱ明显强于过程Ⅰ。两次过程的雷暴大风均由微湿下击暴流引发，过程Ⅰ为孤立风暴产生的微湿下击暴流，过程Ⅱ为飑线系统内嵌的微湿下击暴流。两次过程在微湿下击暴流发生前，多普勒天气雷达高仰角大于45 dBz的强反射率因子缺口均先于低仰角出现。更多还原

【Abstract】 The study utilizes SA Doppler weather radar data from Dalian and Dandong, combined with surface observations and ERA5 reanalysis data, to conduct a comparative analysis of the synoptic background and mechanisms of two mild-wet downburst events over the Liaodong Peninsula: the first on September 11,2020(Event I),and the second on September 10,2021(Event II).Results indicate that both events occur under the influence of a Northeast Cold Vortex.Event I is associated with a cold vertex transformed from a northward typhoon, while Event II involves a cut-off low.Both events are characterized by unstable atmospheric stratifications of "upper-wet and lower-dry",with skew-T diagrams showing an upward-opening "bell-shaped" structure.Near-surface temperature lapse rates are nearly dry-adiabatic.The precipitable water content exceeds 30 mm.The lifting condensation level is low, with CAPE and DCAPE values being relatively small.The 0-6 km wind shear intensity is significantly stronger in Event II than in Event I.The thunderstorm gale events in both cases are induced by wet microbursts, with Event I involving an isolated storm and Event II embedded within a squall line system.In both cases, the Doppler radar reflectivity notches exceeding 45 dBz appear earlier at higher elevation angles than at lower elevation angles prior to the wet microbursts.更多还原