层状云系过冷水区分布规律的飞机观测和数值模拟研究

The distribution rule of super cooled water area in stratiform cloud is the key question of artificial precipitation and aircraft icing.The direct observation of it mainly limited to the plane. A certain number of data and observation have been accumulated through artificial precipitation work in the north part of China, due to the limite of work ,the data is somewhat scattered,so that the distribution rule of it is hard to be reached.This project intends to do a plane observation which is carefully designed,and combined with the three dimensional distribution and evolution data of cloud system obtained through remote sensing methods,such as satellite,radar and air sounding,eventually get the distribution rule of super cooled water in stratiform cloud.We can summarize the space-time distribution characteristic of super cooled water area on different synoptic and cloud system conditions with the help of a large quantity of plane observation.Using CAMS(Chinese Academy of Meteorological Sciences) nonhydrostatic mesoscale cloud model to simulate cloud system,and compare with observation to study the distribution rule and its physical reason of super cooled water area,thus put forward the physical conceptual model of super cooled water area in typical stratiform cloud.This research has important scientific and applicative value on many aspects,such as knowing deep into the physical process of stratiform cloud precipitation,inspecting and improving numerical model,monitoring the potential conditions of artificial precipitation, distinguishing the potential area of plane icing.

层状云系中过冷水区的分布规律是人工增雨和飞机积冰的关键问题。其直接的观测基本限于飞机，我国北方各地通过人工增雨作业和观测已积累一定数量的资料，但由于作业限制，资料比较零散，难于得出其分布规律。本项目拟利用飞机对我国北方层状云系进行有设计的飞机探测；结合卫星、雷达和探空等遥感探测的云系三维分布和演变资料，分析得出过冷水在云系中的分布特征。综合大量飞机探测归纳出不同天气和云层条件下过冷水区分布的时空特征。采用CAMS非静力中尺度云分辨模式对飞机探测的云系进行模拟，通过同实测资料的对比分析，研究过冷水区在云系中的分布规律及其物理原因，提出典型层状云系过冷水区分布的物理概念模型。本研究对于深入认识层状云系降水物理过程、检验和改进数值模式、监测人工增雨潜力条件和判别飞机积冰潜在区等方面，具有重要的科学和应用价值。

通过有设计的飞机等外场观测，共获取飞行资料20余架次，包括卫星、雷达、探空、地面雨量等配套观测资料。结合历史观测资料和中尺度云数值模拟，对其中部分观测和历史个例进行了分析研究。其中，对2009年4月18日低槽冷锋型积层混合云降水过程、2010年4月20日和2012年9月21日西风槽型层状云系的过冷水进行的观测和模拟分析研究结果表明：云系中过冷水含量较为丰富，但空间分布具有不均匀性，在垂直方向上主要位于0℃-10℃之间。过冷水主要位于西风槽前和槽线附近，西风槽前端为高层冷云，云顶温度在-35℃，云体由冰相粒子和过冷水组成，没有暖云，无明显降水；槽线附近云系为冷暖混合云，过冷水较多，云顶温度-20℃，云体最为密实，地面降水较强；云系后部为低层液态水云，云顶温度-5℃，基本没有降水。过冷水分布对应上升运动和高饱和区，高饱和区越深厚、上升运动越强产生的云水值越大。水汽凝结成云滴是云水的主要来源。