Air-Sea CO2 flux estimates in stratified Arctic coastal waters: How wrong can we be?

• Published in: Geophysical Research Letters
• Main Authors: Miller, Lisa A., Burgers, Tonya, Burt, William, Granskog, Mats, Papakyriakou, Tim
• Format: Article in Journal/Newspaper
• Language: English
• Published: AGU 2020
• Subjects: Arctic; air-sea carbon dioxide fluxes; surface waters; ocean stratification; Canada; Norwegian Polar Institute; Sea ice
• Online Access: http://hdl.handle.net/1993/34875; https://doi.org/10.1029/2018GL080099

Summer near-surface seawater sampling in the Canadian Arctic revealed potential for significant errors (nearly 0.1 μmol·(m-2 s -1)) in CO2 fluxes calculated from measured air-sea CO2 gradients. River runoff and sea ice melt strongly stratify these waters, often resulting in surface mixed layers only a few meters thick and isolated from waters sampled by shipboard underway systems. Samples collected with the underway system, rosette, and small boats exposed substantial near-surface gradients in CO2 partial pressure (pCO2) over the top 7 m at many stations. Distributions of temperature, salinity, and fluorescence indicated that the sources of the CO2 system gradients varied between stations, precluding simple corrections to align subsurface data with shallower conditions. Overall, the strong summertime sink of atmospheric CO2 implied by the underway data was not supported by shallower data. Fisheries and Oceans Canada, the Natural Science and Engineering Research Council, the Canadian Foundation for Innovation Major Science Initiatives Fund, and the Centre for Ice, Climate and Ecosystems at the Norwegian Polar Institute