This paper focuses on the rainfall spectrum and its evolution of North China in rainy season with summer monsoon decaying in interdecadal time scale. The interan-nual component of the rainfall is the dominant part, ac...This paper focuses on the rainfall spectrum and its evolution of North China in rainy season with summer monsoon decaying in interdecadal time scale. The interan-nual component of the rainfall is the dominant part, ac-counting for 85% of the total variance, and has been changed significantly during the last 30 years. According to wavelet analysis its 5a periodic spectrum suddenly disappeared in the late 1960s, and its biennial oscillation gradually become weaker and weaker since 1970, accompanied by the summer monsoon decaying. Contrarily, the interdecadal component is principal in the summer monsoon over North China and is very similar to the counterpart of the rainfall. Their interde-cadal parts are significantly correlated, and the correlation coefficient is nearly equal to the one of the original sequences. Besides, the dry and wet climate alternated with the mon-soon abrupt changes in the 1960s and the 1970s over East Asia, apart from North China, climate drifted from a light drought to a severe drought during the past 30 years.展开更多
利用高密度地面自动站逐小时降水观测资料,分析了河南省2010—2015年雨季(5—9月)短时强降水(flash heavy rain, FHR)的时空分布特征。主要结果如下:河南省FHR集中发生在7、8月,其中7月最多,8月次之;河南雨季FHR量、降水贡献和发生频率...利用高密度地面自动站逐小时降水观测资料,分析了河南省2010—2015年雨季(5—9月)短时强降水(flash heavy rain, FHR)的时空分布特征。主要结果如下:河南省FHR集中发生在7、8月,其中7月最多,8月次之;河南雨季FHR量、降水贡献和发生频率的局地差异明显,主要存在4个大值区,即豫北黄河以北地区、豫东商丘地区、豫西南伏牛山以南以东地区、豫南沿淮及其以南地区;地形对降水的增幅作用显著,且主要是通过增加FHR发生频次实现的;FHR频次日变化呈明显的双峰结构,傍晚至凌晨的前半夜为FHR频发时段;4个大值区内FHR频次日变化差异明显,如黄河以北地区其日变化幅度较大、呈单峰型,而沿淮及其以南地区其日变化幅度较小、呈持续活跃型;大部分FHR前后都伴随着连续降水,降水过程的持续时间主要在1～8 h之间,持续时间大于等于3 h的过程主要位于两个与地形密切相关的高频集中区,即伏牛山以东支脉的喇叭口地形区和沿淮及其以南地区。展开更多
基金supported by the National Natural Science Foundation of China(Grant No.49875024)the National Basic Science Research and Developing Program(Grant No.G1998040901)National Key Laboratory LASG
文摘This paper focuses on the rainfall spectrum and its evolution of North China in rainy season with summer monsoon decaying in interdecadal time scale. The interan-nual component of the rainfall is the dominant part, ac-counting for 85% of the total variance, and has been changed significantly during the last 30 years. According to wavelet analysis its 5a periodic spectrum suddenly disappeared in the late 1960s, and its biennial oscillation gradually become weaker and weaker since 1970, accompanied by the summer monsoon decaying. Contrarily, the interdecadal component is principal in the summer monsoon over North China and is very similar to the counterpart of the rainfall. Their interde-cadal parts are significantly correlated, and the correlation coefficient is nearly equal to the one of the original sequences. Besides, the dry and wet climate alternated with the mon-soon abrupt changes in the 1960s and the 1970s over East Asia, apart from North China, climate drifted from a light drought to a severe drought during the past 30 years.
