Influence of biological carbon export on ocean carbon uptake over the annual cycle across the North Pacific Ocean

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• 作者：Hilary I. Palevsky ; Paul D. Quay
• 刊名：Global Biogeochemical Cycles
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：31
• 期：1
• 页码：81-95
• 全文大小：998.5KB
• ISSN：1944-9224

文摘

We evaluate the influences of biological carbon export, physical circulation, and temperature-driven solubility changes on air-sea CO₂ flux across the North Pacific basin (35°N–50°N, 142°E–125°W) throughout the full annual cycle by constructing mixed layer budgets for dissolved inorganic carbon (DIC) and pCO₂, determined on 15 container ship transects between Hong Kong and Long Beach, CA, from 2008 to 2012. Annual air-sea CO₂ flux is greatest in the western North Pacific and decreases eastward across the basin (2.7&thinsp;&plusmn;&thinsp;0.9&thinsp;mol&thinsp;C&thinsp;mp>−2p>&thinsp;yrp>−1p> west of 170°E, as compared to 2.1&thinsp;&plusmn;&thinsp;0.3&thinsp;mol&thinsp;C&thinsp;mp>−2p>&thinsp;yrp>−1p> east of 160°W). East of 160°W, DIC removal by annual net community production (NCP) more than fully offsets the DIC increase due to air-sea CO₂ flux. However, in the region west of 170°E influenced by deep winter mixing, annual NCP only offsets ~20% of the DIC increase due to air-sea CO₂ flux, requiring significant DIC removal by geostrophic advection. Temperature-driven solubility changes have no net influence on pCO₂ and account for <25% of annual CO₂ uptake. The seasonal timing of NCP strongly affects its influence on air-sea CO₂ flux. Biological carbon export from the mixed layer has a stronger influence on pCO₂ in summer when mixed layers are shallow, but changes in pCO₂ have a stronger influence on air-sea CO₂ flux in winter when high wind speeds drive more vigorous gas exchange. Thus, it is necessary to determine the seasonal timing as well as the annual magnitude of NCP to determine its influence on ocean carbon uptake.