The two annual northward jumps of the West Pacific Subtropical High and their relationship with summer rainfall in Eastern China under global warming

• Published in: Chinese physics B 2014-06, Vol.23 (6), p.656-665
• Main Author: 叶天舒 支蓉 赵俊虎 龚志强
• Format: Article
• Language: English
• Subjects: Abnormalities; Belts; China; Global warming; Rain; Ridges; Sea surface temperature; Summer; 中国东部地区; 中国北方; 全球气候变暖; 夏季降水; 西太平洋副热带高压; 西太平洋副高; 跳跃; 长江中下游地区
• ISSN: 1674-1056; 2058-3834; 1741-4199
• DOI: 10.1088/1674-1056/23/6/069203

The two northward jumps of summer West Pacific Subtropical High （WPSH） are defined based on the pentad-scale ridge data of the WPSH ridge in 1951 to 2012. The times of the northward jumps are found to have obvious inter-annual and decadal characteristics, i.e., the occurrence of the first northward jump of WPSH shows a ＂consistently early-consistently late＂ decadal pattern, with the transition around 1980; the occurrence of the second northward jump of WPSH shows a ＂consistently late-consistently early-consistently late＂ decadal pattern, with the transitions about 1955 and 1978, respec- tively, which is consistent with global warming. In the meantime, the times of the two northward jumps not only have a good correspondence to the beginning and ending dates of the rainy season, but also greatly influence the position of the main rain belt in Eastern China. When the first northward jump occurs early, the main rain belt is located from just north of 30~ N to the south of North China, while the opposite situation appears when the first jump occurs late. When the second jump occurs early, more rain falls over North China and South China, but less falls in the Yangtze River region, while the opposite situation appears when the second jump occurs late. In the four cases when abnormalities occur in the same year as early or late northward jumps, the position of the main rain belt can be considered as a superposition of isolated abnormal effects of the two northward jumps. Moreover, the prophase and synchronous forces of the sea surface temperature in the Pacific has great influence on the times of the northward jumps, and the driving forces of the two jumps differ.