[A-CG46] Science in the Arctic Region

[ACG46-02] Subsurface warming process associated with Pacific Summer Water transport north of the Chukchi shelf in the Arctic Ocean

Miaki Muramatsu^1,2, Hiromichi Ueno¹, *EIJI WATANABE², Motoyo Itoh², Jonaotaro Onodera², Kohei Mizobata³ (1.Hokkaido University, 2.Japan Agency for Marine-Earth Science and Technology, 3.Tokyo University of Marine Science and Technology)

Keywords:Arctic Ocean, Pacific Summer Water, Subsurface Temperature Maximum, Chukchi Slope Current

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.