Atmospheric components of the surface energy budget over young sea ice: Results from the N-ICE2015 campaign

The Norwegian young sea ice campaign obtained the first measurements of the surface energy budget over young, thin Arctic sea ice through the seasonal transition from winter to summer. This campaign was the first of its kind in the North Atlantic sector of the Arctic. This study describes the atmospheric and surface conditions and the radiative and turbulent heat fluxes over young, thin sea ice. The shortwave albedo of the snow surface ranged from about 0.85 in winter to 0.72-0.80 in early summer. The near-surface atmosphere was typically stable in winter, unstable in spring, and near neutral in summer once the surface skin temperature reached 0 degrees C. The daily average radiative and turbulent heat fluxes typically sum to negative values (-40 to 0 W m(-2)) in winter but then transition toward positive values of up to nearly +60 W m(-2) as solar radiation contributes significantly to the surface energy budget. The sensible heat flux typically ranges from +20-30 W m(-2) in winter (into the surface) to negative values between 0 and -20 W m(-2) in spring and summer. A winter case study highlights the significant effect of synoptic storms and demonstrates the complex interplay of wind, clouds, and heat and moisture advection on the surface energy components over sea ice in winter. A spring case study contrasts a rare period of 24 h of clear-sky conditions with typical overcast conditions and highlights the impact of clouds on the surface radiation and energy budgets over young, thin sea ice.