The North Pacific Oxygen Uptake Rates Over the Past Half-Century.

Kwon, Eun Young, Deutsch, Curtis, Xie, Shang-Ping, Schmidtko, Sunke and Cho, Yang-Ki (2016) The North Pacific Oxygen Uptake Rates Over the Past Half-Century. Open Access Journal of Climate, 29 (1). pp. 61-76. DOI 10.1175/JCLI-D-14-00157.1.

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Abstract

The transport of dissolved oxygen (O2) from the surface ocean into the interior is a critical process sustaining aerobic life in mesopelagic ecosystems, but its rates and sensitivity to climate variations are poorly understood. Using a circulation model constrained to historical variability by assimilation of observations, we show that the North Pacific thermocline effectively takes up O2 primarily by expanding the area through which O2-rich mixed layer water is detrained into the thermocline. The outcrop area during the critical winter season varies in concert with the Pacific Decadal Oscillation (PDO). When the central North Pacific Ocean is in a cold phase, the winter outcrop window for the Central Mode Water class (CMW; a neutral density range of γ = 25.6 - 26.6) expands southward allowing more O2-rich surface water to enter the ocean’s interior. An increase in volume flux of water to the CMW density class is partly compensated by a reduced supply to the shallower densities of Subtropical Mode Water (γ = 24.0 - 25.5). The thermocline has become better oxygenated since the 1980s due partly to strong O2 uptake. Positive O2 anomalies appear first near the outcrop and subsequently downstream in the subtropical gyre. In contrast to the O2 variations within the ventilated thermocline, observed O2 in Intermediate Water (density range of γ = 26.7 – 27.2) shows a declining trend over the past half-century, a trend not explained by the open ocean water mass formation rate.

Document Type: Article
Additional Information: WOS:000367431600001
Keywords: Circulation/Dynamics, Ocean circulation, Ocean dynamics, Atm/Ocean Structure/Phenomena, Thermocline circulation, Variability, Climate variability, Pacific decadal oscillation, Seasonal cycle
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-PO Physical Oceanography
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1175/JCLI-D-14-00157.1
ISSN: 0894-8755
Projects: EAST-I
Date Deposited: 08 Dec 2015 13:45
Last Modified: 01 Feb 2019 15:09
URI: http://oceanrep.geomar.de/id/eprint/30463

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