本文利用45个高空台站及100余地而台站的资料,对华北地区盛夏的强季风(1973年)和弱季风年(19勺年)进行了对比分析.本文对强、弱季风年分别计算了湿静力能量、高低空流场、风的垂直结构、水汽含量及输送、水汽收支及水分循环等项目,从而得知该两年中各要素场明显差异的主要原因.

This paper,using the high altitude data from 45 stations and the surface data from 100 stations,makes a comparison between strong monsoon year(1973)and weak monsoon year(1972)in North China,and calculates wet static energy,vertical structure of wind of high-and low-level flow fields,the contents and transport of water vapour,the income and export of water an vapour,and water cycle,etc.in strong and weak monsoon years respectively. The following conclusions have been drawn: 1.There was a distinct occluded high energy tongue in the strong monsoon year and a low energy tongue in the weak monsoon year. 2.In the strong monsoon year,western Pacific subtropical high was strong, a wet and warm south air-flow from it met with the drier westerlies nearby 41°N and there were two water vapour transport air-flows.In the weak monsoon year,subtropical high was weak,a wet and warm south air-flow met with westerlies nearby 35°N and there was only one water vapour transport air-flow. 3.The water vapour content of the whole layer in North China in midsummer was 20—40mm and water vapour content was distributed along northeastsouthwest in the strong monsoon year and along latitude in the weak monsoon year. 4.There was a net income of about 95×10⁸m³/month in the strong monsoon year and a deficiency of about 345×10⁸m³/month in the weak monsoon year. 5.Rainfall in North China in midsummer relies mainly on external water vapour supply in both strong and weak monsoon years.