JpGU-AGU Joint Meeting 2017

Presentation information

[EE] Poster

A (Atmospheric and Hydrospheric Sciences) » A-AS Atmospheric Sciences, Meteorology & Atmospheric Environment

[A-AS06] [EE] Advances in Tropical Cyclone Research: Past, Present, and Future

Sat. May 20, 2017 10:45 AM - 12:15 PM Poster Hall (International Exhibition Hall HALL7)

convener:Masuo Nakano(Japan Agency for Marine-Earth Science and Technology), Akiyoshi Wada(Typhoon Research Department Meteorological Research Institute), Sachie Kanada(Nagoya University), Kosuke Ito(University of the Ryukyus)

[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.