EGU General Assembly 2021
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Correcting Net Ocean-Atmosphere CO2 Fluxes for Near-surface Temperature Deviations.

Andrew J. Watson1, Jamie D. Shutler2, Peter Landschützer3, David K. Woolf4, Thomas Holding2, Lonneke Goddijn-Murphy5, Ute Schuster1, and Ian G. C. Ashton2
Andrew J. Watson et al.
  • 1University of Exeter, Global Systems Institute, Exeter, UK (
  • 2Department of Geography, Penryn Campus, University of Exeter, UK
  • 3Max Planck Institute for Meteorology, Hamburg, Germany
  • 4International Centre for Island Technology, Herriot-Watt University, Stromness, Orkney, UK
  • 5Environmental Research Institute, University of the Highlands and Islands, Ormlie Road, Thurso, UK

We have recently shown the neglect of small temperature differences in the ocean mixed layer has led to substantial underestimates in the ocean sink for atmospheric CO2 as calculated from surface pCO2 observations, which we find should be increased by ~0.8 Pg Cyr-1 when globally integrated. Surface observations of ocean pCO2 such as those in the SOCAT (Surface Ocean CO2 Atlas, are reported at a temperature typically  measured at several metres depth, but co-location of satellite estimates of the subskin surface temperature (at a few centimetres depth) differ from this, and are on average lower. In addition the top millimetre or so of the ocean is cooler than the underlying subskin because the ocean is a source of radiative and latent heat to the atmosphere. These two temperature deviations have subtly different effects on the air-sea flux of CO2 as calculated by the gas exchange equation, but both result in an increase in the flux into the ocean and the combined effect is large. We are making available several datasets enabling calculation of these effects, including the regular provision of SOCAT data corrected to the subskin temperature, a climatology of the skin temperature deviation, and corrected ocean-atmosphere CO2 flux estimates for the period since 1985.

How to cite: Watson, A. J., Shutler, J. D., Landschützer, P., Woolf, D. K., Holding, T., Goddijn-Murphy, L., Schuster, U., and Ashton, I. G. C.: Correcting Net Ocean-Atmosphere CO2 Fluxes for Near-surface Temperature Deviations., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4768,, 2021.


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