Abstract: Microphysical properties of stratocumulus clouds are investigated using data from CloudSat cloud profiling radar for the subtropical East Pacific region. CloudSat retrieval indicates that droplet number concentration remains approximately constant in the vertical direction. The effects of aerosol particles on cloud microphysical properties and liquid water path are studied using data from the cloud profiling radar onboard CloudSat and data from MODIS. It is found that, for constant liquid water path, increasing aerosols can lead to decreased droplet effective radius. However, the aerosol effect on cloud droplet radii is not significant as seen in previous studies. It is difficult to find the effect of aerosols on cloud liquid water path because the liquid water path itself has high variability in the stratocumulus clouds. In addition, it is found that liquid water path derived from CloudSat is higher than that from MODIS, and that the variability of liquid water path in stratocumulus clouds is greater than that of aerosol optical depth in the ambient.

Key words: CloudSat, MODIS, aerosol-cloud interaction, stratocumulus cloud, liquid water path

摘要： 利用CloudSat的云雷达数据研究了太平洋东部副热带地区的层积云微物理特性。结果显示, CloudSat反演的云滴数浓度在垂直方向变化很小。结合CloudSat的云雷达数据和MODIS的气溶胶数据, 研究了气溶胶对层积云的微物理特性和液态水路径的影响。结果表明: 对于相同的液态水路径, 气溶胶增加可以使得云滴的尺度减小, 但总体上对云滴尺度的影响并不显著; 由于云中液态水路径本身变化极大, 导致气溶胶对液态水路径的影响很难和云中液态水路径本身的变化分离开。此外还发现: CloudSat反演的层积云液态水路径比MODIS反演的液态水路径偏高; 层积云内液态水路径的不均一性比环境气溶胶光学厚度的不均一性大。

关键词: CloudSat, MODIS, 气溶胶-云相互作用, 层积云, 液态水路径