JpGU-AGU Joint Meeting 2017

講演情報

[EE] ポスター発表

セッション記号 A (大気水圏科学) » A-AS 大気科学・気象学・大気環境

[A-AS06] [EE] 台風研究の新展開~過去・現在・未来

2017年5月20日(土) 10:45 〜 12:15 ポスター会場 (国際展示場 7ホール)

コンビーナ:中野 満寿男(海洋研究開発機構)、和田 章義(気象研究所台風研究部)、金田 幸恵(名古屋大学宇宙地球環境研究所)、伊藤 耕介(琉球大学)

[AAS06-P13] Influence of the IOD on the relationship between El Nino Modoki and the East Asian-western North Pacific summer climate

*Juan Feng1 (1.Institute of Atmospheric Physics, Chinese Academy of Sciences)

The relationship between El Nino Modoki and the East Asian-western North Pacific summer monsoon (EA-WNPSM) has been revealed to be under the influence of Indian Ocean Dipole (IOD). When a pure El Nino Modoki occurs without a positive IOD, a strong EA-WNPSM is observed with a significant anomalous low-level cyclone over the western North Pacific (WNP), excessive rainfall there and deficient Meiyu–Baiu rainfall. In contrast, when an El Nino Modoki happens simultaneously with a positive IOD, the anomalous EA-WNPSM tends to be much weaker. This difference is attributed to a positive IOD effect. The results demonstrate that a positive IOD usually leads to a strong South Asian summer monsoon heating, which further causes easterly anomalies in the western Pacific. These anomalous easterlies tend to strengthen the WNP anticyclonic vorticity leading to a weak EA-WNPSM. Therefore, a positive IOD weakens the relationship between the El Nino Modoki and the EA-WNPSM. In addition, numerical experiments verified that the strong low-level WNP cyclonic anomaly is built through the off-equatorial heating associated with the local cyclonic circulation. The anomalous WNP anticyclonic vorticity induced by a positive IOD weakens this off-equatorial heating, thus leading to a weak EA-WNPSM.