北美温带气旋及其对纽约降水的影响

利用西半球１９８０－１９９０年常规天气图资料及纽约逐日降水资料，将冬半年北美温带气旋分为３类，分析了它们的气候特征，形成过程及其对纽约降水的影响。结果表明：北美温带气旋冬半年平均频数５１个，年际变化不大，月际分布最多月为１２个，最少月只有５个；不同类型气旋的时间分布及对纽约降水的影响存在明显差异。

Extratropical Cyclone in North America and Its Influence on Precipitation of New York

Using routine weather maps of west hemisphere and daily precipitation data of New York from 1980 to 1990,extratropical cyclone in North America has been classified as three types.The climatic features,process of formation of three types and its influence on rainfall of New York have been analysed.The results show that the mean frequency of extratropical cyclone during winter time is fifty one,its annual chang is small;Cyclone number is twelve in maximum month,five in minimum month,the distribution on time of three types of cyclones and their affection on precipitation of New York are different.