Atmos. Chem. Phys. Discuss., 8, 15825-15853, 2008
© Author(s) 2008. This work is distributed
under the Creative Commons Attribution 3.0 License.
Review Status
This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
The impact of diurnal variability in sea surface temperature on the atlantic air-sea CO2 flux
H. Kettle1, C. J. Merchant1, C. D. Jeffery2, M. J. Filipiak1, and C. L. Gentemann3
1School of GeoSciences, The University of Edinburgh, UK
2National Oceanography Centre, Southampton, UK
3Remote Sensing Systems, Santa Rosa, CA, USA

Abstract. The effect of diurnal variations in sea surface temperature (SST) on the air-sea flux of CO2 over the central Atlantic ocean and Mediterranean Sea is evaluated for 2005–2006. We use high resolution hourly satellite SST data to determine the diurnal warming (ΔSST). The CO2 flux is then computed using three different temperature fields – a foundation temperature (Tf, measured at a depth where there is no diurnal variation), Tf plus the hourly ΔSST and Tf plus monthly-averaged ΔSST. This is done in conjunction with a physically-based parameterisation for the gas transfer velocity (NOAA-COARE). The differences between the fluxes evaluated for these three different temperature fields quantifies the effects of both diurnal warming and diurnal covariations. We find that including diurnal warming increases the CO2 flux out of the Atlantic for 2005–2006 from 9.6 Tg C a−1 to 30.4 Tg C a−1 (hourly ΔSST) and 31.2 Tg C a−1 (monthly ΔSST). Diurnal warming, therefore, has a large impact on the annual net CO2 flux but diurnal covariations in variables are negligible implying that CO2 fluxes may be adequately computed using monthly averaged ΔSSTs along with a suitable foundation temperature.

Citation: Kettle, H., Merchant, C. J., Jeffery, C. D., Filipiak, M. J., and Gentemann, C. L.: The impact of diurnal variability in sea surface temperature on the atlantic air-sea CO2 flux, Atmos. Chem. Phys. Discuss., 8, 15825-15853, doi:10.5194/acpd-8-15825-2008, 2008.
Search ACPD
Discussion Paper
    Final Revised Paper