摘要:在CM1模式动力框架基础上，推导出结合尺度分析得到的强对流天气发生发展的必要条件，并选择典型东北冷涡背景下的飑线过程，以200 m的高精度水平网格距进行数值模拟和对比试验，验证理论结果的同时得到东北冷涡飑线形成的条件。通过模式数据做尺度分析，得到飑线系统中平流、对流以及沉降作用对水汽变量的影响最大，飑线的出现需要水汽分布和上升气流的配合，水汽相变影响次之，湍流作用相对较小。东北冷涡不同区域的模拟验证了理论分析的结果，冷涡西南侧受冷涡引导南下的冷空气影响，配合低层暖平流出现不稳定层结，结合有横向梯度的湿度场，可以形成飑线。在上升气流强的区域受水汽浓度和温度的影响在中高层容易形成强的雷达回波，两侧和积分一段时间后的低层受沉降作用的影响也会出现强的雷达回波。
关键词:CM1云模式/
东北冷涡/
飑线/
发展机制
Abstract:Based on the dynamic frame of CM1 model, the necessary conditions for the occurrence and development of severe convective weathers are obtained by theoretical derivation and scale analysis. A typical squall line process under the background of Northeast Cold Vortex (NECV) is selected, and the numerical simulation and comparative test are carried out with a high precision horizontal grid distance of 200 m. The theoretical results are verified and the conditions for the formation of a squall line under the NECV are obtained. Through the scale analysis of model data, it is found that advection, convection and hydrometeor precipitation have the greatest influence on the change of moisture variables in the squall line system, the influence of water vapor phase change is the secondary, and the turbulence effect is relatively small. Thereby, the occurrence of the squall line needs the cooperation of water vapor distribution and the ascending air flow. Simulations over different regions of NECV have verified the results of theoretical analysis. In the southwestern side of the NECV, upper levels are affected by cold air, which, when combined with warm advection in lower levels, leads to the formation of unstable stratification. The unstable stratification and transverse gradient pattern of humidity field can jointly lead to the formation of the squall line. Under the influence of water vapor concentration and temperature, strong radar echoes can easily form in the middle and upper levels with strong updrafts. Under the influence of precipitation, strong radar echoes can also be found in lower levels.
Key words:CM1 cloud mode/
Northeast Cold Vortex (NECV)/
Squall line/
Development mechanism
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