关键词: CloudSat, Aqua, 降水云, 冰粒子有效半径

Abstract: The water problem of Xinjiang has two sides:one is that the shortage of water resources has increasingly become a serious threat to the economic sustainable development, and another is that flood, waterlogging, landslide and debris flow caused by heavy rainfall are the main natural disasters in the region. A lot of researches were conducted on heavy rainfall, yet which were mainly focused on the climatological characteristics and dynamics of heavy rainfall. Cloud, the carrier and indicator of rainfall, is still less involved due to a lack of observation data. The role of clouds in rainfall process was studied with the traditional static and polar orbit satellite data, while passive remote sensing observation instruments loaded on satellite can only reflect the average state of whole the atmosphere. In this paper, employing the retrieval data 2B-CLDClASS and 2B-CWC-RVOD from cloud profiling radar onboard CloudSat satellite and CERES Aqua MODIS Edition 3A from NASA, the heavy rain happened along Tianshan Mountain in northern Xinjiang on April 28, 2008 was studied. Cloud classification and the vertical distribution of cloud microphysical properties and its correlation with precipitation were analyzed. It was found that the cloud distributed from 1 to 12 km in the study area, while the ice cloud distributed from 2 to 11 km and ice particles were only within altostratus, deep convective clouds, and stratus, cumulus and high clouds. The deep convective clouds, stratus and cumulus exists precipitation clouds in the research region. Overall, regardless of height, the smaller the cloud parameters value, the greater the occurrence. Ice effective radius (IER) varied from 27.1 μm and 180.2 μm. IER emerged obvious stratification in the vertical height and the lower the cloud layer, the higher the IER value. Particles with IER more than 150 μm, accounted for 18.11 percent, concentrated distribution within 2-4 km height layer. 85.6 percent of particles with IER within 100-150 μm distributed in 2-6 km. Those with IER less than 50 μm, accounted for 26.88 percent, were distributed in the whole cloud and the percentage increased with height. Ice water content (IWC) ranged from 1 mg·m^-3 to 1361 mg·m^-3, while the domain of values was wide. Particles with IWC less than 50 mg·m^-3 accounted for 60.74 percent and those with IWC more than 500 mg·m^-3 was only 1.66 percent. IWC averages showed Gaussian distribution in vertical height and high IWC particles appeared at 6-7 km height layer. Particles with IWC more than 500 mg·m^-3 and IWC between 300-500 mg·m^-3 were distributed in 2-8 km and peaks appeared in 5-6 km, which were 33.33% and 35.473% respectively. What is more, IWC and ice water path of clouds in raining areas were larger than those in the areas of non-precipitation. Ice number concentration (INC) showed an increasing trend with the increasing of height and varied from 0.1 L^-1 to 351.5 L^-1 and the mid-value was 77.365 L^-1. Particles with INC less than 50 L^-1 accounted for 48.19 percent and those with INC greater than 200 L^-1 was only 5.67 percent.

Key words: CloudSat, Aqua, precipitation cloud, Ice effective radius