初冬一次层状云较弱云区垂直结构的飞机观测

为分析层状云垂直微物理结构，了解雷达参数特征，揭示降水机制，利用机载Ka波段云雷达和DMT（Droplet Measurement Technologies）粒子测量系统，针对2019年11月17日山东冷锋层状云系开展从云顶至云底的垂直探测。结果表明:观测云层由高层云（3100~4500 m高度）和雨层云（800 ~2600 m高度）两部分组成。高层云过冷水含量较低，平均值为0.0026 g·m-3，最大值为0.008 g·m-3，云内冰晶通过水汽凝华增长，平均浓度为8.2 L-1，最大直径为900 μm，平衡谱状态下冰晶浓度与雷达反射率因子具有较好相关性，相关系数最大为0.84。雨层云过冷水含量丰富，最大含水量为0.354 g·m-3，过冷水区平均雷达反射率因子为7.48 dBZ，多普勒速度为-2.3 m·s-1，速度谱宽为0.7 m·s-1；雨层云中上部以冰晶为主，下部为暖区融化粒子，冰晶通过凇附过程增长，平均浓度为208 L-1，最大直径为450 μm；雷达反射率因子随高度降低至1500 m不断增大，在1200~1500 m高度保持不变，1200 m高度以下减小，未出现明显0℃亮带，速度谱宽随高度降低增大。

Aircraft Measurement of the Vertical Structure of a Weak Stratiform Cloud in Early Winter

In order to obtain the vertical microphysical structure of the stratiform cloud and characteristics of the radar parameters and reveal the precipitation mechanism, the airborne Ka-band cloud radar and DMT particle measurement system are used to target the stable precipitation layer of a cold front in Shandong Province on 17 November 2019. The results show that the observed cloud layer consists of two parts: Altostratus (As, 3100-4500 m) and nimbostratus (Ns, 800-2600 m). The content of As supercooled water is low, with an average value of 0.0026 g·m-3 and the maximum value of 0.008 g·m-3. The average ice crystal content in the cloud is 8.2 L-1. In the vertical space, the ice crystal size and spectral are different. Ice crystals grow through deposition, with a maximum diameter of 900 μm. In the state of equilibrium spectrum, the ice concentration has a good correlation with radar reflectivity, and the maximum correlation coefficient is 0.84. The movement of particles in the cloud is different. The speed of small particles varies greatly and is easily affected by updrafts. The falling speed of large-scale ice crystals is stable. The central part of the Ns (1750-2150 m) is rich in supercooled water, with the maximum content of 0.354 g·m-3. The average radar reflectivity of the supercooled water region is 7.48 dBZ, the Doppler velocity is -2.3 m·s-1, and the velocity spectral width is 0.7 m·s-1. The height of the supercooled water layer in the cloud can be comprehensively judged by combining a variety of detection data and parameters. The upper part of the Ns is dominated by ice crystals and the lower part is filled by melted particles in the warm zone. The average concentration of ice crystals is 208 L-1, which increases through the riming process, and the maximum diameter is 450 μm. The radar reflectivity profile increases as the height decreases from 2200 m to 1500 m, remains unchanged from 1500 m to 1200 m, and decreases below 1200 m. There is no obvious bright band at 0℃ level, and the velocity spectral width profile increases as the height decreases. The supercooled water in the stratiform cloud in early winter is abundant, and the concentration of ice crystals meets the standard of seeding area, which has a certain potential for rainfall enhancement.