层状云微物理属性垂直分布的季节变化——以新疆地区为例

利用CloudSat卫星资料2B-CLDCLASS和2B-CWC-RVOD数据集，分别揭示了层云与层积云的云粒子等效半径、数浓度及含水量等微物理属性的垂直分布特征及其季节变化规律。结果表明：层云所在的云层高度比层积云高，特别是春季，层云可以延伸到11.0 km处，而层积云云层所在高度最高出现在夏季，最高延伸到8.5 km处。层云中的冰水分布在1.0~11.0 km，液态水分布在0~9.0 km，而层积云的冰水和液态水均分布在0~9.0 km。层云与层积云的冰粒子等效半径、水云粒子数浓度、液态水含量呈现随云层高度的增加而减小的趋势，冰粒子数浓度随云层高度增加呈增大趋势，冰水含量呈峰值分布，峰值出现在6~10 km范围内。各季节层积云粒子等效半径、粒子数浓度及水含量的最大值均大于层云的对应值，从这方面看，层积云更适合作人工增水对象。

Vertical distribution and its seasonal variation of microphysical properties of stratiform clouds in Xinjiang

Xinjiang has a typical temperate continental climate and complex topography with large diurnal temperature difference. The spatial and temporal distribution of precipitation is extremely uneven due to various factors of climate and terrain,which accelerated the water shortages in the Xinjiang. Studies have found that strati-form cloud shows a great potential on artificial enhancement precipitation,however,due to lacks of observation measurements,few researches focused on the vertical distribution of stratiform clouds. CloudSat is the first satellite,which can observe the vertical distribution of worldwide cloud microphysical properties by using active millimeter-wave radars. In this paper,based on the retrieval data 2B-CLDClASS and 2B-CWC-RVOD from cloud profiling radar onboard CloudSat satellite,stratiform clouds that contained stratus and stratocumulus appeared in Xinjiang during 2009-2010 were chosen to reveal the vertical distribution of stratiform cloud microphysical properties including the equivalent radius of ice particles and water cloud particles,the concentration of ice particle and water cloud particle,the content of ice water and liquid water and its seasonal variation. Results show that the ice water and liquid water were distributed in 1.0-11.0 km and 0-9.0 km respectively in the stratus clouds,while in 0-9.0 km in the stratocumulus clouds. The effective radius of ice particles in both stratocumulus and stratus decreased with the height of cloud. The maximums of ice effective radius were 106.4 μm and 70.8 μm respectively appeared in the bottom of clouds. The water cloud particles effective radius of stratocumulus was larger than stratus',with the high value both appeared in the lower cloud layer,and the maximums were 15.7μm and 12.5 μm respectively. The ice number concentration in stratocumulus increased with the increase of cloud height,the maximum was 76.4 L-1 distributed in 8.0-9.0 km;while the ice number concentration in stratus increased with height ranging from 0 to 9.0 km. The number concentration of water cloud particle decreased with the increase of height of both stratocumulus and stratus. The water cloud particle number concentration in stratocumulus was greater than in stratus ranging from 1.0 to 6.0 km,but lower than in stratus in the top of the cloud layer ranging from 6.0 to 9.0 km and in the bottom. The peak of ice water content value in stratocumulus appeared in 7.0-8.0 km,which was 50.3 mg·m^-3,and the peak of ice water content of stratus occurred in 8.0-9.0 km,which was 25.1 mg·m^-3. The liquid water content of stratocumulus,which was up to 500.4 mg·m^-3,was much greater than stratus' when they appeared in range from 0 km to 7.0 km. From this perspective,stratocumulus clouds were more suitable for artificial cloud-seeding. Stratus and stratocumulus clouds occurred more frequently in the spring,summer and autumn but less in winter,especially stratocumulus clouds. The height of stratus clouds was higher than those of stratocumulus clouds,particularly in spring,stratus clouds were extended to 11.0 km. The maximum height of stratocumulus clouds was 8.0km in summer.