Influence of warm-core eddy on dissolved methane distributions in the southwestern Canada basin during late summer/early fall 2015

• Published in: Polar Science
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2019
• Subjects: Arctic ocean; Dissolved methane; Warm-core eddy; Arctic; Arctic Ocean; Chukchi Sea; Canada; canada basin; Chukchi; Polar Science
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=15998; http://id.nii.ac.jp/1291/00015888/

We examined vertical profiles of methane (CH4) concentrations inside and outside of a warm-core eddy during a cruise of the R/V Mirai cruise (MR15-03 Leg. 1) in the Arctic Ocean in late summer/early fall 2015. Because a coherent mesoscale eddy is one of the possible mechanisms for transporting shelf water from the Chukchi Sea into the Canada Basin interior, we hypothesized that the warm-core eddy transported dissolved CH4 as well as nutrients and impacted the distribution of CH4. Seawater samples were therefore collected to obtain detailed vertical profiles of CH4 concentrations in the southwestern Canada Basin. We found high CH4 concentrations in bottom water on the shelf, which was located outside the warm-core eddy. The percent saturation in that water was as high as 947% of atmospheric CH4. We also found that sub-surface CH4 peaks within the radius of the maximum velocity of the eddy were broader at depth than those outside of the eddy. Lateral transport of the eddy was likely the controlling factor responsible for subsurface CH4 peaks within the warm-core eddy. Our study indicated that eddies play a crucial role in controlling and transporting CH4 laterally and vertically.