A mesoscale convective system (MCS) embedded in a cold frontal cloud system over Beijing on July 16, 2018 was investigated using X-band dual-polarization radar observations from Fangshan Station and sounding data from the Beijing Observatory. This study focused on hydrometeor identification and microphysical characterization, yielding the following key findings. 1) The ice-phase hydromorphic species above the 0°C layer differed in different stages and regions of this MCS. From the stage of development to maturity to dissipation, the main hydromorphic species in the region with combined reflectance larger than 40 dBZ were graupel and snow, and the proportion of ice crystals was relatively low. In the region with combined reflectance between 20 and 40 dBZ, graupel, snow, and ice crystals were the main hydromorphic species. In these two regions, the proportion of graupel gradually decreased with time, while the proportion of snow and ice crystals gradually increased with time. In the region with combined reflectance smaller than 20 dBZ, the proportion of graupel was very low, and the main hydromorphic species were snow and ice crystals, with the proportion of snow gradually decreasing with time, and the proportion of ice crystals gradually increasing with time. 2) The area of the 20–40 dBZ echo region in this MCS played a dominant role in precipitation area. 3) At the beginning of convection, satellite brightness temperature observation had a better monitoring effect on precipitation. The application of X-band dual-polarization radar data to analyze the microphysical characteristics of MCS is beneficial to understand the microphysical processes occurring in the system, and can provide a useful reference for the revision of the microphysical parameterization scheme. 

利用北京房山X波段双偏振雷达观测资料和北京市观象台探空资料, 对2018年7月16日发生在北京地区冷锋云系的中尺度对流系统(MCS)进行水成物种类识别和微物理特征分析, 得到如下结果。1) 0℃层以上的冰相水成物种类在这次MCS的不同阶段和不同区域存在差异。从发展到成熟再到消散阶段, 组合反射率大于40 dBZ的区域主要水成物是霰和雪, 冰晶的比例较低, 组合反射率在 20~40 dBZ之间的区域主要水成物是霰、雪和冰晶, 这两个区域内霰的比例均随时间逐渐减少, 雪和冰晶的比例随时间逐渐增加。组合反射率小于20 dBZ的区域霰的比例非常低, 主要水成物是雪和冰晶, 雪的比例随时间逐渐减少, 冰晶的比例随时间逐渐增加。2) 本次MCS中, 20~40 dBZ回波区域的面积对降水面积起主导作用。3) 在对流刚发生时, 卫星亮温观测对降水有较好的监测作用。应用X波段双偏振雷达资料分析MCS微物理特征有利于理解系统发生的微物理过程, 可为微物理参数化方案的修正提供有益的参考。