中国东部降水的气候模态及雨季划分

Climate modes of precipitation in eastern China and division of rainy season

应用中国东部地面观测气候平均候降水量数据和谐波分析方法,研究了华南、长江中下游、淮河流域、华北四个区域降水的年变化特征,特别是夏季风降水的阶段性和区域特征,并对构成降水年变化的气候分量进行分析,将各区降水年变化分解为年循环模态、季节模态、季节内振荡和月内振荡四个气候模态。结果表明:不同模态间的相互调制对降水的阶段性和区域性具有重要影响,年循环是影响雨季的主要模态,季节和季节内振荡模态对决定主汛期起重要作用。基于气候模态划分中国东部雨季和主汛期,方法简单,结果客观合理。

Using the climatological mean pentad precipitation data in eastern China,annual variations of monsoon precipitation within the four subareas,i.e.South China,the middle-lower reaches of Yangtze River,Huaihe Basin and North China,are studied.Especially the stages and regional features of summer monsoon precipitation are discussed in detail.By harmonic analysis method,climatological variation of precipitation within each subarea is decomposed into annual cycle mode,seasonal mode,intra-seasonal oscillation mode and intra-monthly oscillation mode.Results show that the impact of interactions among the four modes on the stages and regional features of precipitation are significant.The annual cycle mode is the main mode influencing rainy season,and the seasonal mode and CISO （climatological intraseasonal oscillation） mode are important to determine the flood season.Based on the four climate modes,a new division method of rainy season and flood season in eastern China is put forward.It may be more objective and reasonable as compared to former division methods,though the method is simple.