摘要:
本文通过13个中尺度α类对流性云团的分析,给出其生命史中各阶段的典型云型。发生发展的对流层低层流场模型及成熟时的空间结构。分析表明:暖季在我国高原东部较低纬度地区,存在着与美国中纬度地区相似的中尺度对流复合体(MCC)。它们发生在高空小槽底部,低空偏南风急流左侧和地面冷峰西端的南侧或准静止锋上的暧湿辐合区中。当锋面向东南移动时,低层多方向的辐合进一步加强。云团暴发性发展,在凌晨达到最强,伴随的降水也急剧加强成暴雨或大暴雨;午后云团减弱消失,降水也随之迅速减弱;云团成熟时,椭圆形云团色调白亮、密实,长轴达7个纬距,辐合层可到达300百帕,中心轴线近于垂直且为暖心结构,对200百帕流场有明显的影响。
Abstract:
This paper shows the typical cloud patterns of the life cycle of the meso-α-scale convective cloud clusters, the flow patterns in the lower troposphere in their formative and developing stages and the vertical structure in the mature stage. The results show that in the warm season there are mesoscale convective complexes (MCC) in South China and they are similar to those that occur in the central United States. They form in the upper-level trough, in the left side of the lower-level jet, and in the surface pre-frontal area. As the front moves southeastwards, cloud clusters develop rapidly in the area where convergence is strongest. The clusters are strongest in the early morning, at that time the precipitation is also most intensive, the precipitation becomes weaker in noon. In the satellite images the cloud cluster appears in a dense and isolate oval-shape cloud area, its longer axis is about 800 km. Within the cluster from sea-level to 300 hPa there is convergence, and a warm core when the cloud cluster is in mature stage
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