Is AOU a good measure of respiration in the oceans?

• Published in: Geophysical Research Letters
• Main Authors: Follows, Michael J, Boyle, Edward A, Ito, Takamitsu
• Other Authors: Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology. Program in Atmospheres, Oceans, and Climate, Woods Hole Oceanographic Institution
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union (AGU) 2004
• Subjects: Sea ice
• Online Access: http://hdl.handle.net/1721.1/106326

Apparent Oxygen Utilization (AOU) is widely used to infer respiration in the oceans by assuming that surface oxygen concentration is close to saturation with the overlying atmosphere. However, significant disequilibrium of oxygen has been observed in high latitude surface oceans where the deep waters are formed. We explicitly calculate True Oxygen Utilization (TOU) in a global ocean physical-biogeochemical model to evaluate the ability of AOU to represent respiration. We find significant differences between AOU and TOU in the deep waters, suggesting a systematic overestimation of respiration when inferred from AOU. The surface heat flux and the entrainment of thermocline waters together drive the surface undersaturation of oxygen in the regions of water mass formation, and their influences are significantly enhanced by sea ice cover at high latitudes. National Science Foundation (U.S.). Division of Polar Programs National Science Foundation (U.S.) (Grants OCE-0136609 and OCE-0350672)