[A-OS12] Marine ecosystems and biogeochemical cycles: theory, observation and modeling

[AOS12-P01] Impact of mesoscale eddies on particulate organic carbon flux in the western subarctic North Pacific

*Ryo Dobashi¹, Hiromichi Ueno², Nozomi Matsudera³, Isao Fujita⁴, Tetsuichi Fujiki⁵, Makio C. Honda⁵, Naomi Harada⁵ (1.Graduate School of Fisheries Sciences, Hokkaido University (Present address: University of Hawaii at Manoa), 2.Faculty of Fisheries Sciences, Hokkaido University, 3.Graduate School of Environmental Sciences, Hokkaido University, 4.Graduate School of Fisheries Sciences, Hokkaido University, 5.Japan Agency for Marine-Earth Science and Technology)

Keywords:Western subarctic North Pacific, Particulate organic carbon, Mesoscale eddy

The mechanism that controls particulate organic carbon (POC) flux in the deep sea differs depending on the season and sea. The POC produced in the western subarctic North Pacific are known to be transported to the deep sea efficiently, but the direct relationship between the POC flux and physical processes is still unclear. In this study, we evaluated the effect of mesoscale eddies on POC flux in the western subarctic North Pacific. The seasonal and interannual variabilities of POC flux were investigated using data from a time-series sediment trap deployed at 4,810 m at station K2 (47°N, 160°E) from 2005 to 2018. POC flux was high during May–November, appearing to reflect spring and fall blooms at the ocean surface. POC flux also showed interannual variability, with twelve peaks that were mostly affected by enhanced bloom just before the peak. Nine peaks of the twelve peaks were affected by mesoscale eddies, which enhanced bloom around K2 by extending the area with a high chlorophyll-a concentration along the coastal region into the offshore region, suggesting that mesoscale eddies strongly impact the interannual variability of POC flux at K2.