一次降水性积层混合云系的微物理特征分析

利用山东省2007年10月27日1架次机载粒子测量系统（Particles Measuring System,PMS）积层混合云探测资料,分析了云中粒子浓度和尺度、液态含水量,以及小云滴和大云滴谱的垂直分布特征,比较了催化前后云微物理特征的变化。结果表明,催化前,云层中小云滴谱型为单峰,谱宽随高度增加先变窄后变宽,大云滴谱型在云低层为单峰,中高层为双峰谱,谱宽随高度增加先变宽后变窄,并且没有探测到降水粒子。催化后,小云滴尺度在低层减小、高层增加,整层液态水含量减小;大云滴浓度增加,尺度增大,出现降水粒子,固态粒子类型增多。在3 700~4 000 m高度层内小于10μm粒子明显增加,说明凝结过程比较明显,并且10~27.5μm粒子开始出现,启动了云滴的碰并机制。小云滴谱变化较小,基本为单峰谱,但在较大云滴处谱型略有起伏,在3 000m和3 300m高度的谱宽增宽。大云滴粒子谱有较大的变化,低层变成双峰谱,谱宽最宽可达650μm,中高层为双峰或多峰,峰值从小值向较大值移动。2D-P探头在催化云高层探测到降水粒子,谱型呈单调下降形态,谱宽最大为600μm。

An Analysis of Microphysical Characteristics on Precipitation Cumulus-Stratus Mixed Clouds System

Based on one aircraft flights cumulus-stratus mixed clouds system data sampled with probes of Particles Measuring System（PMS） on 27 October 2008 in Shandong Province,the vertical distributions of concentration and diameter of cloud particles,and liquid water content（LWC）,and spectrum of small and large cloud droplets are analyzed.The changes of cloud microphysical characteristics before and after seeding are compared.Results show that,before seeding,small cloud droplets spectrum appears unimodal vertical distribution with spectrum width broadened after first-narrow,and big cloud droplets spectrum unimodal（bimodal） vertical distribution in the lower layer（in the middle and high layers） with spectrum width narrowed after first-wide,and precipitation droplet is not observed by 2D-P.After seeding,cloud droplets diameter reduces（increases） in low layer（in high layer）,and liquid water content in the whole layer decreases.The concentration and diameter of big cloud droplets increase,precipitation particles appear,and solid particles increase.The particles of smaller than 10 μm increase significantly in 3 700—4 000 m height layers,indicating that condensation process is obvious,and 10—27.5 μm particles begin to appear because the collision mechanism of cloud particles has started.The small cloud droplets spectrum is unimodal distribution,but the large cloud droplets spectrum has fluctuating with spectrum width broadened in 3 000 m and 3 300 m height layers.The large cloud droplets spectrum shows bimodal distribution with maximum spectrum width of 650 μm in the low layer,and bimodal and multimodal distribution in the middle and high layers with peak moving from small to large values.The 2D-P probe can observe the precipitation particles in high layer of seeding cloud,and the spectrum type decreases monotonically with maximum spectrum width of 600 μm.