基于CloudSat资料的北上江淮气旋暴雪云系结构特征

2007年3月3-5日和2013年11月24-25日，受江淮气旋北上影响，我国北方大部地区遭遇罕见暴风雪天气，2次暴雪过程有很多相似之处.利用常规观测、CloudSat卫星云廓线雷达的探测资料和NECP/NCAR再分析资料，分析了这2次暴雪过程江淮气旋云系结构和微物理特征.结果表明：（1）北上江淮气旋的冷锋云系较窄，以深厚对流云为主，回波核心在2~7 km，其结构在气旋发展的不同阶段变化不大；（2）逗点头云系范围宽广，在气旋的不同发展阶段，结构和强度有显著差异.气旋初始锋面波动和锋面断裂阶段，逗点头云系有两个降水区：北部为由多个单体组成的大范围层状云区，强回波从地表向上伸展，上空有高空对流泡，建立了播撒云-供水云机制，有利于下部冰晶粒子长大；南部有对流云柱发展.逗点头西部的冷输送带云系主要集中在6 km以下，强度弱，冰粒子含量少；（3）气旋暖锋后弯阶段，干侵入加强，冷锋后部的无云区或少云区范围扩大，逗点头云系南北范围收缩、变窄，云系的高度、强度和含水量减弱，冷锋云系也减弱；（4）气旋冷锋云系和逗点头南部的对流云柱以降雨为主，位于高纬度陆地上的逗点头云系以降雪为主，当逗点头云系处于海上有对流不稳定发展，以降雨为主.冷锋云系北部和逗点头云系南部均有由层积云或高积云组成的低云，以毛毛雨为主.冷锋云系和逗点头云系北部100-200 km的范围为随高度和距离逐渐变薄的高层云，无降水对应.

Structure of the snowstorm cloud associated with northward Jiang-huai cyclone based on Cloudsat satellite data

Two unusual snowstorm events occurred in northern part of China on 3-5 March 2007 and 24-25 November 2013, respectively. They were triggered by northward Jiang-huai cyclones and have many similar features. The cloud structure and microphysical characteristic were analyzed by using routine observation data, cloud profile radar data from Cloudsat and NECP/NCAR reanalysis data. Main results show that:(1) Cold front cloud system of northward Jiang-huai cyclone is narrow and dominated by deep convective cloud, whose structure and intensity have little change in different develop stages of cyclone. The echo core is between 2 km and 7 km. (2) Comma head cloud system is broader, and its structure and intensity have a big difference in different development stages of cyclone. There are two zones of precipitation within the comma head:a northern zone characterized by wide range stratiform clouds topped by generating cells and a southern zone marked by convective cloud column in the incipient frontal cyclone and frontal fracture stages. The strong radar echo stretched from surface. The feeder-seeder mechanism is set up, which is favorable to the ice crystal growth. The cloud system of cold conveyor belt are mainly beneath 6km, with weak intensity and small ice water content. (3) Dry intrusion intensified in the bent-back warm front stage of cyclone, which lead to the wideness of the cloud-free area or partly cloudy area behind the cold front. The range of the comma head narrowed, and the cloud height, intensity and water content decrease. (4) Cold front cloud system and convective cloud column located in the southern part of comma head mainly produce rainfall, while comma head cloud at high latitude cause snowfall. However, convective instability develop and result in rainfall when comma head cloud is over the sea. Shallow cloud in the northern side of the cold front cloud system or the southern side of the comma head, which is composed of cumulostratus or altocumulus, produce drizzle. 100~200 km north of the cold front and the comma head are altostratus, which become thin with the increase of the height and distance, no corresponding precipitation.