Surface Energy Fluxes of Arctic Winter Sea Ice in Barrow Strait

Abstract

The surface energy balance of sea ice was measured during degree one-week periods in November, January, and February of 1980?81 in the Barrow Strait, Northwest Territories, Canada. Turbulent fluxes were derived with the bulk aerodynamic transfer method, using temperature, dewpoint, and wind speed profile measurements. The conductive heat flux was balanced by the sensible and latent heat fluxes, and by the radiative fluxes for all three measuring periods. In November, when there was a mean ice thickness of 0.32 m, approximately 80%, ±6% of the conductive heat flux (? 129 W m?2) was dissipated by the sensible heat flux (108 W m?2), approximately 20% ± 8% of the energy was lost by longwave radiation (30 W m?2), and the latent heat flux (6 W m?2) accounted for 4% of the total surface energy balance. Ice growth rates could be predicted for young ice with an accuracy of 10%, based on conductive flux measurements. Brine-wetted snow on sea ice increased the conductive heat flux to two Lorries that of pure snow. In January, when there was a mean ice thickness of 0.92 m, approximately 50% ± 9% of the conductive heat flux (?50 W m?2) was dissipated by sensible heat flux (26 W m?2), approximately 50% ± 9% was dissipated by radiative cooling (27 W m?2), and the latent heat flux had a mean value of 0 W m?2. Variations in the surface energy balance tend to be related to synoptic events, such as the horizontal advection of warm air and the increased cloudiness of transient eddies. In February, the mean conductive heat flux was ?36 ± 4 W m?2, which was balanced by the radiative flux of 32 ± 2.5 W m?2 (80% ± 8%) and by the sensible flux of 10 W m?2 (20% ± 6%). Again, large-scale synoptic events dominated the surface energy balance. On a weekly basis, the mean surface energy balance residuals were within the predicted uncertainties, based on instrument resolution.