Frontal Rain and Summer Monsoon Rain During Pre-rainy Season in South China. Part II: Spatial Patterns
华南前汛期的锋面降水和夏季风降水 II. 空间分布特征

Following Part I of this study,spatial patterns of frontal rain and summer monsoon rain during pre-rainy season in South China are explored in this paper.In order to reveal the spatial patterns,the data of 730 surface stations of China and the start dates of summer monsoon rain in South China determined by Part I are used to compute the precipitation(strength) of frontal rain and summer monsoon rain during pre-rainy season and their time series are obtained.The main spatial patterns are found and the relationship between frontal rain and summer monsoon rain is explored by EOF(Empirical Orthogonal Function) analysis and extended EOF(EEOF) analysis.The results indicate that frontal rain and summer monsoon rain during pre-rainy season in South China have three important spatial patterns,including below normal(above normal) in the whole region,above normal(below normal) in the southwestern region and below normal(above normal) in the northeastern region,above normal(below normal) in the southeastern region and below normal(above normal) in the northwestern region.Through analyzing the relations between the spatial patterns and 850 hPa wind,the leading pattern of frontal rain corresponds to southwesterly(northeasterly) in the north of South China and northeasterly(southwesterly) in the south of South China,while the leading pattern of monsoon rain corresponds to southwesterly(northeasterly) in South China that represent summer monsoon strength.Relations between the second and third patterns of frontal and monsoon rain and lower tropospheric wind indicate to some extent that different front and monsoon control areas form different patterns.The distributions of frontal rain correspond well to that of summer monsoon rain during pre-rainy season in South China.