Effect of seasonal change in gas transfer coefficient on air–sea CO2 flux in the western North Pacific

• Published in: Journal of oceanography Vol. 71; no. 6; pp. 685 - 701
• Main Authors: Xiong, Xuanrui, Masuda, Yoshio, Hashioka, Taketo, Ono, Tsuneo, Yamanaka, Yasuhiro
• Format: Journal Article
• Language: English
• Published: Tokyo Springer Japan 01.12.2015; Springer Nature B.V
• Subjects: Carbon cycle; Carbon dioxide; Cold regions; Earth and Environmental Science; Earth Sciences; Ecosystem models; Fluctuations; Freshwater & Marine Ecology; Gas exchange; Marine ecosystems; Monsoons; Ocean circulation; Ocean-atmosphere interaction; Oceanography; Original Article; Seasonal variations; Seasons; Seawater; Summer; Winter; Pacific Ocean; Air–sea CO; Ecosystem model; Gas transfer coefficient; Seasonal change; flux; CO; North Pacific; East Asian winter monsoon
• ISSN: 0916-8370; 1573-868X
• DOI: 10.1007/s10872-015-0313-5

We used an eddy-permitting three-dimensional ocean ecosystem model and applied it in the western North Pacific to understand the seasonal variations and horizontal distributions of the air–sea CO 2 flux and difference in the partial pressure between sea water and the atmosphere (∆ p CO 2 ). The high-resolution model reproduced the observed zonal belt of strong CO 2 uptake in the mid-latitude (30–45°N) western North Pacific including the Kuroshio extension and mixed water regions, which was difficult to show in previous coarse-resolution models. The East Asian winter monsoon, an important phenomenon in the western North Pacific, affects the seasonal CO 2 air–sea gas exchange with a high (low) gas transfer coefficient in winter (summer). In the subtropical region, ∆ p CO 2 is negative in winter and positive in summer as a result of the temperature effect. Combination of seasonal change in gas transfer coefficient with ∆ p CO 2 suppresses CO 2 release in the subtropical region, and vice versa in the subarctic region (i.e., suppresses CO 2 uptake). That is, the East Asian winter monsoon in the western North Pacific contributes to the reduction of the annual CO 2 flux through the seasonal change in the gas transfer coefficient, leading to an overall annual CO 2 uptake in the subtropical region and CO 2 release in the subarctic region.