日本地球惑星科学連合2018年大会

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-OS 海洋科学・海洋環境

[A-OS10] Atlantic climate variability, and its global impacts and predictability

2018年5月20日(日) 15:30 〜 17:00 ポスター会場 (幕張メッセ国際展示場 7ホール)

コンビーナ:Ingo Richter(JAMSTEC Japan Agency for Marine-Earth Science and Technology)、Noel S Keenlyside (Geophysical Institute Bergen)、Carlos R Mechoso (共同)、Yoshimitsu Chikamoto(Utah State University)

[AOS10-P01] South Atlantic Anti-Cyclone as a driver of Atlantic Niño variability

*Noel S Keenlyside1William Cabos2Dmitry Sein3Shunya Koseki1Hyacinth Nnamchi4 (1.Geophysical Institute, University of Bergen and Bjerknes Centre, Norway、2.University of Alcalá, Spain、3.Alfred Wegener Institute for Polar and Marine Research, Germany、4.University of Nigeria, Nigeria)

キーワード:Tropical Atlantic, Climate Prediction, Atlantic Niño, Climate Modelling

Atlantic Niño variability remains poorly understood and predicted, despite exhibiting some apparent similarities to the El Niño Southern Oscillation. Here we show that extra-tropical influences play a dominant role in driving Atlantic Niño variability, bringing a new dimension to our understanding. We assess the role of extra-tropical atmospheric variability in driving observed Atlantic variability by comparing ensemble simulations with two configurations of a regional coupled climate model. In one case the South Atlantic Anticyclone is prescribed at the southern boundary of the regional atmospheric model, while in the other it is simulated within the domain. In both configurations, atmospheric reanalysis drive the global ocean model outside of the coupled domain and are prescribed as boundary conditions to the regional atmospheric model. Extra-tropical southern hemisphere variability can explain around 50% of the observed Atlantic Niño variability. The greatest impact is from boreal spring and autumn. Comparing models different resolution and parameterisations shows the importance of representing the link between SAA and equatorial Atlantic variability in capturing the observed Atlantic Niño variability. The link between the two regions appears related to thermodynamic ocean-atmosphere interaction.