[A-CG43] 北極域の科学

[ACG43-02] 大気エネルギー収支から見た最近数十年間にわたる北極域温暖化増幅の地域性と季節性の特徴

*吉森 正和¹、堀 正岳¹ (1.東京大学大気海洋研究所)

キーワード：北極域温暖化増幅、大気熱輸送

The Arctic has been warming more rapidly than other parts of the globe. This geographical pattern of climate change is called Arctic amplification (AA). There have been many studies investigating the local feedback processes that lead to the enhanced warming in the Arctic. These studies include ones analyzing the energy balance at the top-of-the-atmosphere and/or at the surface, and have made substantial progress in our understanding of how Arctic feedbacks contribute to AA. On the other hand, there have been also many studies investigating the role of atmospheric heat and moisture transport in AA. They also made substantial progress in our understanding. Recently, the importance of coupling between Arctic regional feedbacks and transport of heat and moisture from outside of the Arctic was pointed out. It is this coupling that the current study makes attempt to elucidate by analyzing the temperature tendency terms in the atmosphere. We analyze the global atmospheric reanalysis dataset, JRA-55 produced by Japan Meteorological Agency. It is shown that there are two prominent regions of strong warming in the Arctic over the last several decades: the Arctic Pacific sector and Arctic Atlantic sector, but they differ in seasonal timing of the maximum warming. By analyzing the temperature tendency terms leading up to the maximum warming, we reveal which tendency terms play what roles in AA for each region. It is shown that the increasing horizontal temperature advection leads to the peak seasonal warming in January for the Arctic Atlantic sector whereas the increasing surface sensible heat flux from the ocean leads to the peak seasonal warming in October for the Arctic Pacific sector. Further decomposition of horizontal temperature advection terms is also presented.