A negative phase shift of the winter AO/NAO due to the recent Arctic sea-ice reduction in late autumn

Nakamura, Tetsu; Yamazaki, Koji; Iwamoto, Katsushi; Honda, Meiji; Miyoshi, Yasunobu; Ogawa, Yasunobu; Ukita, Jinro

A negative phase shift of the winter AO/NAO due to the recent Arctic sea-ice reduction in late autumn

Nakamura, Tetsu; Yamazaki, Koji; Iwamoto, Katsushi et al.

Journal of geophysical research atmospheres, 2015, 120(8), 3209-3227

Permalink : https://hdl.handle.net/2115/60135

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アクセス権	open access
URI	https://hdl.handle.net/2115/60135
タイトル	A negative phase shift of the winter AO/NAO due to the recent Arctic sea-ice reduction in late autumn
著者	Nakamura, Tetsu ; Yamazaki, Koji ; Iwamoto, Katsushi ; Honda, Meiji ; Miyoshi, Yasunobu ; Ogawa, Yasunobu ; Ukita, Jinro
著者名 Nakamura, Tetsu
著者名 Yamazaki, Koji
著者名 Iwamoto, Katsushi
著者名 Honda, Meiji
著者名 Miyoshi, Yasunobu
著者名 Ogawa, Yasunobu
著者名 Ukita, Jinro
言語	英語
キーワード	Arctic sea-ice loss
	Arctic Oscillation
	long-term changes
	severe winter
発行日	2015-04-28
出版者	American Geophysical Union
収録物名	Journal of geophysical research atmospheres
巻(号)	120(8)
ページ	3209-3227
抄録	This paper examines the possible linkage between the recent reduction in Arctic sea-ice extent and the wintertime Arctic Oscillation (AO)/North Atlantic Oscillation (NAO). Observational analyses using the ERA interim reanalysis and merged Hadley/Optimum Interpolation Sea Surface Temperature data reveal that a reduced (increased) sea-ice area in November leads to more negative (positive) phases of the AO and NAO in early and late winter, respectively. We simulate the atmospheric response to observed sea-ice anomalies using a high-top atmospheric general circulation model (AGCM for Earth Simulator, AFES version 4.1). The results from the simulation reveal that the recent Arctic sea-ice reduction results in cold winters in mid-latitude continental regions, which are linked to an anomalous circulation pattern similar to the negative phase of AO/NAO with an increased frequency of large negative AO events by a factor of over two. Associated with this negative AO/NAO phase, cold air advection from the Arctic to the mid-latitudes increases. We found that the stationary Rossby wave response to the sea-ice reduction in the Barents Sea region induces this anomalous circulation. We also found a positive feedback mechanism resulting from the anomalous meridional circulation that cools the mid-latitudes and warms the Arctic, which adds an extra heating to the Arctic air column equivalent to about 60% of the direct surface heat release from the sea-ice reduction. The results from this high-top model experiment also suggested a critical role of the stratosphere in deepening the tropospheric annular mode and modulation of the NAO in mid to late winter through stratosphere-troposphere coupling.
資源タイプ	学術雑誌論文
出版タイプ	Version of Record
権利情報	Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
PISSN	2169-897X
関連情報 (isIdenticalTo)	出版社版DOI https://doi.org/10.1002/2014JD022848