不同季节北大西洋上爆发性气旋云微物理特性的分析与比较

Analyses and Comparison of Cloud Microphysical Characteristics of Explosive Cyclones in Different Seasons over the Northern Atlantic Ocean

本文利用CloudSat卫星产品、MODIS(Moderate Resolution Imaging Spectroradiometer)可见光云图和欧洲中期天气预报中心提供的ERA5再分析资料,对不同季节北大西洋上四个爆发性气旋个例的云微物理特性的垂直结构进行了分析,结果表明,爆发性气旋所伴随的云系以雨层云、深对流云和高层云为主,云系最大高度可达12 km以上;深对流云和雨层云中常出现雷达反射率大值区,存在较强的对流运动;云中冰粒子沿0℃等温线开始出现,冰粒子尺度随高度的增加而减小,秋季个例和冬季个例的冰粒子有效半径最大值大于春季个例和夏季个例;在深对流云和雨层云内部,冰粒子数浓度随高度的增加而增大,大尺度冰粒子更为集中,出现冰水含量大值区,冰粒子数浓度最大值和冰水含量最大值以秋季个例的数值最大,冬季和春季个例次之,夏季个例最小。

In this paper,cloud microphysical characteristics of four explosive in different seasons over the Northern Atlantic Ocean were analyzed and compared by using CloudSat satellite data provided by Cloud Sat Data Processing Laboratory,MODIS visible cloud pictures provided by National Aeronautics and Space Administration,as well as ERA5 reanalysis data provided by European Centre for Medium-Range Weather Forecasts(ECMWF).As a result,explosive cyclones are covered by various clouds mainly including nimbostratus,deep convection,and altostratus.The maximum height of cloud system may even go up to 12 km.Deep convection and nimbostratus accompany stronger convective motions with a great radar reflectivity in a certain region.Ice particles start appearinig near the 0℃isotherm,particle size decreases as the height increment.The maximum effective radius of ice particles in the fall case and the winter case are generally greater than that in the spring case and the summer case.The ice particle number concentration increases as the height increment inside deep convective and nimbostratus.Large scale ice particles are more concentrated,resulting in the greater ice water content.Both maximum of ice particle number concentration and ice water content are the largest in the fall case,followed by the winter case and the spring case,and the smallest in summer case.