Effect of seasonal change in gas transfer coefficient on air-sea CO sub(2) 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: 01.12.2015
• Subjects: Marine; INW, Pacific, Kuroshio Current; IN, North Pacific
• 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 sub(2) flux and difference in the partial pressure between sea water and the atmosphere ( Delta pCO sub(2)). The high-resolution model reproduced the observed zonal belt of strong CO sub(2) uptake in the mid-latitude (30-45 degree 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 sub(2) air-sea gas exchange with a high (low) gas transfer coefficient in winter (summer). In the subtropical region, Delta pCO sub(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 Delta pCO sub(2) suppresses CO sub(2) release in the subtropical region, and vice versa in the subarctic region (i.e., suppresses CO sub(2) uptake). That is, the East Asian winter monsoon in the western North Pacific contributes to the reduction of the annual CO sub(2) flux through the seasonal change in the gas transfer coefficient, leading to an overall annual CO sub(2) uptake in the subtropical region and CO sub(2) release in the subarctic region.