Aircraft Observation Research on Macro and Microphysics Characteristics of Continental Cumulus Cloud at DifferentDevelopment Stages

CAI Zhaoxin , CAI Miao , LI Peiren , LI Junxia , SUN Hongping , GU Yu , GAO Xin 2014年7月3日，山西省人工降雨防雹办公室在该省忻州地区开展了国内首次大陆性积云飞机穿云探测。本文利用机载云物理探测资料，分析研究了不同发展阶段的积云宏、微观物理特性，主要结论有：（1）初生发展阶段的积云水平尺度约为8.2 km×5.5 km（经向×纬向，下同），云厚约2 km；云中以小云粒子为主，云滴凝结增长；水平方向上，云液水含量（LWC）和粒子浓度（N _c ）的最大值均位于云体中心位置；垂直方向上，云水分布相对均匀，但随着高度增加，云粒子浓度变小，粒子尺度增大；粒子谱符合伽马分布，峰值量级为10 ² cm ^-3 μm ^-1 ，谱宽在100 μm以下。（2）成熟阶段的积云水平尺度约为4.6 km×10 km，云厚约4 km；云内可以观测到积冰和雨线；小云粒子浓度随高度增加起伏变化，3600 m、4100 m和4900 m高度处存在峰值；大云粒子浓度随高度先增加后减小，最大值出现云底以上1.6 km高度，云底以上1.3 km高度附近有降水粒子形成；粒子谱呈多峰分布，暖区符合伽马分布，冷区为伽马分布和M-P分布相结合，且随着高度的增加拓宽，4400 m高度以下的谱宽小于200 μm。（3）消散阶段积云尺度约为11 km×5.6 km，云厚约2 km，云下有降水粒子存在。 Abstract: Weather Modification Office of Shanxi Province organized an in-situ observation through continental cumulus clouds for the first time on 3 July 2014 in China. Based on the airborne cloud physical data, macro and microphysical properties of continental cumulus cloud at different development stages were analyzed. The main results (1) For growing cumulus, the horizontal scale is about 8.2 km×5.5 km (meridional direction×zonal direction, the same hereinafter) and cloud depth is 2 km. The cloud is dominated by small particles, which gradually grow through the condensation process. The maximum cloud water content (LWC) and particle number concentration (N _c ) appear at the horizontal direction of cloud center. In the vertical direction, N _c decreases and particle effective diameter (ED) increases with height, while LWC distribution is uniform. The particle spectrum is consistent with gamma distribution, and the peak magnitude is 10 ² cm ^-3 μm ^-1 , where the spectral width is less than 100 μm. (2) For mature cumulus, the horizontal scale is about 4.6 km×10 km and cloud depth is 4 km. The ice and rain lines can be seen in the cloud. N _c varies with height, with three peaks occurring at heights of 3600 m, 4100 m, and 4900 m. The concentration of large cloud particles initially increases first and eventually decreases with height. The maximum value appears at a height of 1.6 km above the bottom of the cloud. Precipitation particles can be formed near the height of 1.3 km above the cloud base. The particle spectrum is multimodal. The spectrum can be described as a gamma distribution in the warm cloud region. In the cold cloud region, the spectrum is mostly a combination of gamma distribution and M-P distribution. The particle spectrum broadens with increasing height, and the spectral width is less than 200 μm below 4400 m. (3) For dissipating cumulus, the horizontal scale is about 5.6 km×11 km and cloud depth is 2 km. Precipitation particles are present under the cloud.