中国地区夏季云粒子尺寸的时空分布特征

利用CloudSat卫星资料,分析了2006～2008年中国地区夏季月平均云粒子有效半径的垂直和区域变化特征。结果显示,水云粒子有效半径在对流层低层达到最大,并随高度增加而减小。30°N纬度带的水云相对以南及以北纬度带的粒子有效半径偏大。6月水云粒子有效半径较大,应与梅雨季节有密切联系。对于中国北部和中部,水云粒子有效半径在西部较东部偏大,而在南部地区,东西部差异不明显。不同纬度带上的冰云粒子有效半径相类似,在冰云下边界最大,随高度增加而减小。水云和冰云的云粒子尺度的年际变化不明显。对上述特征的成因分析表明,高原地形以及东亚夏季风对月平均云粒子有效半径具有明显影响。所揭示的云粒子有效半径特征为天气和气候模式改进、人工影响天气及云—辐射—气候相互作用等研究提供了重要的基础信息。

Tempo-Spatial Distribution Characteristics of Cloud Particle Size over China during Summer

By using the data provided by CloudSat satellite, the study examines the vertical, geographic, and monthly variations of cloud particle effective radius over China during the summer of 2006-2008. Results show that the liquid cloud droplet effective radius is larger in the low tropospheric atmosphere than that in the middle and upper ones, and it decreases with the altitude. The liquid cloud droplet effective radius is larger in middle latitude zone than that in southern or northern latitude zones. The cloud droplet effective radius is smaller in July and August, while it is larger in June. This feature may be closely related to the Meiyu front systems. The cloud droplet effective radius is larger in the west part and is smaller in the east part of northern and central China, while there is very small difference between the east and west part of southern China. The characteristics of ice particle sizes in the three different latitudinal zones are similar to each other, in which the ice particle effective radii get the maximum value at ice cloud base and decrease with altitude. The inter-annual variation of either liquid or ice cloud particle sizes are not significant. From the features mentioned above, it can be seen the significant influences of plateau topography and East Asian summer monsoon on the vertical and geographic distributions of monthly cloud particle effective radius. The revealed features of monthly cloud particle effective radius can provide baseline information for the further researches on weather and climate models improvement, weather modification and cloud-radiation-climate interaction.