基于星载云雷达资料的东亚大陆云垂直结构特征分析

A study of cloud vertical profiles from the Cloudsat data over the East Asian Continent

中文关键词:  Cloudsat资料  云垂直结构  降水云和非降水云  雷达反射率  频数分布

英文关键词:Cloudsat data  Cloud vertical profile  Precipitation and non-precipitation cloud  Radar reflectivity  Frequency distribution

中文摘要:

      利用近5年(2006年6月-2011年4月)的Cloudsat卫星资料分析了东亚大陆云垂直结构特征.结果表明:(1)降水(文中可降水是根据观测到的可降水粒子信息计算到达地面的降水,并不是指地面观测到的实际降水)云和非降水云的雷达反射率(回波)垂直分布存在一定差异,除降水云反射率通常接地外,降水云主要集中在8km以下,反射率通常为-20-15dBz,非降水云主要集中在4-12km,反射率为-28-0dBz;降水云雷达反射率频数大值中心在2-4km,对应的雷达反射率为0-10dBz,而非降水云出现在8-10km,且对应的雷达反射率为-26--24dBz;(2)从雷达反射率廓线来看,降水云中雷达反射率随高度的变化先增强后减弱,而非降水云几乎不变;(3)液态降水云、固态降水云和毛毛雨降水云反射率的垂直分布明显不同;(4)液态降水云自11至7km雷达反射率迅速增强,表明此高度是粒子快速增长的优势空间;(5)固态降水云中-15℃温度频数分布与雷达反射率频数大值中心有很好的对应关系,表明在-15℃附近的条件下冰相粒子凝华 碰冻是粒子增长的优势过程;(6)云的垂直结构随着季节变更而变化,降水云春季、夏季和秋季的雷达反射率垂直分布变化不明显,而冬季主要在低层;固态降水云的垂直分布频数大值中心从春季至冬季呈“双 单”中心交替变化,且与云中-15℃频数分布变化一致;非降水云雷达反射率垂直分布没有明显的季节变化;(7)深对流云和雨层云是形成降水粒子的主要云型.

英文摘要:

      The Cloudsat satellite data during June 2006 to April 2011,were used to investigate the cloud vertical profiles over the East Asian region (20°-50°N, 80°-120°E),with particular emphasis on comparing the differences between radar reflectivity profiles of precipitation and non-precipitation clouds, as well as seasonal variations of these profiles. The results show that: (1)Ucnerally, the radar reflectivity of precipitation clouds mainly locates at below 8 km with dBz between -20 and 15,while the radar reflectivity of non-precipitation clouds locates at 4-12 km with dBz between -28-0 with the radar reflectivity of precipitation being able to usually reach to ground;(2) there are differences among liquid precipitation,solid precipitation, and possible drizzle precipitation clouds profiles;(3) the radar reflectivity increases gradually from 11 km to 7 km with the temperatures always below 0℃ in liquid precipitation clouds,suggesting that condensation and collision-coalescence processes play a vital role in the formation of large-size liquid drops;(4) the frequency distribution of temperature at -15℃ is consistent with the high radar reflectivity in solid precipitation clouds, meaning that the temperature at -15℃ or so is advantageous to deposition and accretion processes; (5) the vertical distribution of liquid precipitation clouds changes slightly from spring to autumn, but mainly in the low-level in winter; the vertical distribution of solid precipitation clouds changes with alternate double and single high-frequency with the season,and this is consistent with the variation of the frequency distribution of temperature at -15℃;the non-precipitation clouds vertical distribution changes little with season;and (6) the deep connective and nimbostratus clouds are the major types of cloud generating precipitation drops.