Biases in the air-sea flux of CO2 resulting from ocean surface temperature gradients
McGillis, Wade R.
Jessup, Andrew T.
DeGrandpre, Michael D.
Hare, Jeffrey E.
Edson, James B.
MetadataShow full item record
The difference in the fugacities of CO2 across the diffusive sublayer at the ocean surface is the driving force behind the air-sea flux of CO2. Bulk seawater fugacity is normally measured several meters below the surface, while the fugacity at the water surface, assumed to be in equilibrium with the atmosphere, is measured several meters above the surface. Implied in these measurements is that the fugacity values are the same as those across the diffusive boundary layer. However, temperature gradients exist at the interface due to molecular transfer processes, resulting in a cool surface temperature, known as the skin effect. A warm layer from solar radiation can also result in a heterogeneous temperature profile within the upper few meters of the ocean. Here we describe measurements carried out during a 14-day study in the equatorial Pacific Ocean (GasEx-2001) aimed at estimating the gradients of CO2 near the surface and resulting flux anomalies. The fugacity measurements were corrected for temperature effects using data from the ship's thermosalinograph, a high-resolution profiler (SkinDeEP), an infrared radiometer (CIRIMS), and several point measurements at different depths on various platforms. Results from SkinDeEP show that the largest cool skin and warm layer biases occur at low winds, with maximum biases of −4% and +4%, respectively. Time series ship data show an average CO2 flux cool skin retardation of about 2%. Ship and drifter data show significant CO2 flux enhancement due to the warm layer, with maximums occurring in the afternoon. Temperature measurements were compared to predictions based on available cool skin parameterizations to predict the skin-bulk temperature difference, along with a warm layer model.
Author Posting. © American Geophysical Union, 2004. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 109 (2004): C08S08, doi:10.1029/2003JC001800.
Suggested CitationArticle: Ward, Brian, Wanninkhof, Rik, McGillis, Wade R., Jessup, Andrew T., DeGrandpre, Michael D., Hare, Jeffrey E., Edson, James B., "Biases in the air-sea flux of CO2 resulting from ocean surface temperature gradients", Journal of Geophysical Research 109 (2004): C08S08, DOI:10.1029/2003JC001800, https://hdl.handle.net/1912/3757
Showing items related by title, author, creator and subject.
Evaluation of the National Oceanic and Atmospheric Administration/Coupled-Ocean Atmospheric Response Experiment (NOAA/COARE) air-sea gas transfer parameterization using GasEx data Hare, Jeffrey E.; Fairall, Christopher W.; McGillis, Wade R.; Edson, James B.; Ward, Brian; Wanninkhof, Rik (American Geophysical Union, 2004-07-16)During the two recent GasEx field experiments, direct covariance measurements of air-sea carbon dioxide fluxes were obtained over the open ocean. Concurrently, the National Oceanic and Atmospheric Administration/Coupled-Ocean ...
How well does wind speed predict air-sea gas transfer in the sea ice zone? A synthesis of radon deficit profiles in the upper water column of the Arctic Ocean Loose, Brice; Kelly, Roger P.; Bigdeli, Arash; Williams, W.; Krishfield, Richard A.; Rutgers van der Loeff, Michiel M.; Moran, S. Bradley (John Wiley & Sons, 2017-05-05)We present 34 profiles of radon-deficit from the ice-ocean boundary layer of the Beaufort Sea. Including these 34, there are presently 58 published radon-deficit estimates of air-sea gas transfer velocity (k) in the Arctic ...
Stanley, Rachel H. R.; Jenkins, William J.; Lott, Dempsey E.; Doney, Scott C. (American Geophysical Union, 2009-11-19)Air-sea gas exchange is an important part of the biogeochemical cycles of many climatically and biologically relevant gases including CO2, O2, dimethyl sulfide and CH4. Here we use a three year observational time series ...