[A-CG42] 北極域の科学

[ACG42-P15] 北極海カナダ海盆の海氷縁付近におけるメゾスケール渦とサブメゾスケール渦

*小平 翼¹、早稲田 卓爾¹、藤原 泰²、君塚 政文³、勝野 智嵩¹、川口 悠介⁴、野瀬 毅彦¹、藤原 周⁵ (1.東京大学　大学院新領域創成科学研究科、2.神戸大学　、3.東京都立産業技術高等専門学校、4.東京大学　大気海洋研究所、5.海洋研究開発機構)

キーワード：北極海、サブメゾスケール、海洋表層ドリフター、海氷

Submesoscale oceanic eddies are small-scale, ageostrophic phenomena in the ocean that contrast with their geostrophic counterparts, which typically transfer energy to larger scales through an inverse cascade. Submesoscale eddies, however, are believed to significantly contribute to the downward energy cascade, a process highlighted by D'Asaro et al. (2011) for its potential importance. This downward cascade is particularly relevant in the Arctic Ocean, where three-dimensional turbulence plays a critical role in regulating the upward vertical heat flux from the subsurface warm layers to the surface layer and sea ice.
The analysis of temporal changes in the mean distance between drifter pairs allows for the estimation of relative dispersion and lateral turbulent diffusivity (LaCasce, 2008). Mensa et al. (2018) found that the near-surface lateral diffusivity over the ice-free Beaufort Sea is comparable to values inferred at midlatitudes.
To advance our comprehension of submesoscale and mesoscale eddies within the marginal ice zone, we deployed a series of ocean surface drifters in proximity to the sea ice edge across the Canada Basin as part of the JAMSTEC R/V Mirai Arctic cruise in 2023. This study presents an initial analysis of the drifter trajectories, which conspicuously demonstrate the presence of several mesoscale eddies within the area of investigation. Moreover, the data from the drifters indicate oceanic dispersion effects that can be attributed to submesoscale eddies. These findings imply that the dispersion of the drifters is predominantly influenced by mesoscale eddies, underscoring the importance of accurately estimating lateral diffusivity to understand these dynamics further.