[A-CG38] 北極域の科学

[ACG38-P03] On the atmospheric response experiment to a Blue Arctic Ocean

*中村 哲¹、山崎 孝治¹、本田 明治²、浮田 甚郎²、Jaiser Ralf³、Handorf Doerthe³、Dethloff Klaus³ (1.北海道大学大学院地球環境科学研究院、2.新潟大学理学部自然環境科学科、3.アルフレッドウェゲナー研究所)

キーワード：北極海氷後退、北極振動、気候変動、極端気候、極域増幅

We demonstrated atmospheric responses to a reduction in Arctic sea ice via simulations in which Arctic sea ice decreased stepwise from the present-day range to an ice-free range. In all cases, the tropospheric response exhibited a negative Arctic Oscillation (AO)-like pattern. An intensification of the climatological planetary-scale wave due to the present-day sea ice reduction on the Atlantic side of the Arctic Ocean induced stratospheric polar vortex weakening and the subsequent negative AO. Conversely, strong Arctic warming due to ice-free conditions across the entire Arctic Ocean induced a weakening of the tropospheric westerlies corresponding to a negative AO without troposphere-stratosphere coupling, for which the planetary-scale wave response to a surface heat source extending to the Pacific side of the Arctic Ocean was responsible. Because the resultant negative AO-like response was accompanied by secondary circulation in the meridional plane, atmospheric heat transport into the Arctic increased, accelerating the Arctic amplification.