[A-CG46] 北極域の科学

[ACG46-02] チュクチ海北方域における太平洋夏季水の輸送に伴う亜表層貯熱量の増加過程

村松 美幌^1,2、上野 洋路¹、*渡邉 英嗣²、伊東 素代²、小野寺 丈尚太郎²、溝端 浩平³ (1.北海道大学、2.海洋研究開発機構、3.東京海洋大学)

キーワード：北極海、太平洋夏季水、亜表層水温極大、チュクチ陸棚外縁境界流

We investigated the interannual variabilities in the subsurface ocean heat content (OHC) in the Chukchi Borderland and its relationship with the Chukchi Slope Current and the Beaufort Gyre conditions. The subsurface OHC in the Chukchi Borderland increased from 1999 to 2020. The decadal trend was 16.62 MJ m⁻² year⁻¹. This increase of the subsurface OHC in the Chukchi Borderland was related to the interannual variabilities in the subsurface northward heat flux and OHC in Barrow Canyon, which is located in the upstream region of the Chukchi Slope Current. While the heat flux across the Barrow Canyon section did not show a significant positive decadal trend from 2002 to 2018, the trend of the subsurface OHC in the canyon was significantly positive. Moreover, the analysis of the satellite-based geostrophic velocity field indicated that the Chukchi Slope Current across the southern boundary in the Chukchi Borderland became faster from 2011 to 2020. This intensification of the Chukchi Slope Current was associated with the southeastward shift of the Beaufort Gyre. Therefore, we suggested that the larger subsurface OHC in Barrow Canyon and the intensification of the Chukchi Slope Current increased the PSW transport to the Chukchi Borderland and contributed to the larger subsurface OHC in the Chukchi Borderland in the 2010s.