Results

Seasonal cycle and long-term trend of solar energy fluxes through Arctic sea ice
Arndt and Nicolaus (2014, TC; doi:10.5194/tc-8-2219-2014)

In this study, we quantify solar shortwave fluxes through sea ice for the entire Arctic during all seasons. We present a new parameterization of light transmittance through sea ice for all seasons as a function of variable sea ice properties. The maximum monthly mean solar heat flux under the ice occurs in June, enough heat to melt 0.3 m of sea ice. Furthermore, our results suggest that 96% of the annual solar heat input through sea ice occurs during only a 4-month period from May to August. Applying the new parameterization, we find an increase in transmitted light of 1.5 %yr-1  for all regions. Sensitivity studies reveal that the results depend strongly on the timing of melt onset and the correct classification of ice types.

Radiation fluxes through Arctic sea ice

Changes in Arctic sea ice result in increasing light transmittance and absorption
Nicolaus et al. (2012, GRL, doi:10.1029/2012GL053738)

We presented the first large-scale under-ice light measurements, operating spectral radiometers on a remotely operated vehicle (ROV) under Arctic sea ice in summer. This data set is used to produce an Arctic-wide map of light distribution under summer sea ice. Our results show that transmittance through first-year ice (FYI, 0.11) was almost three times larger than through multi-year ice (MYI, 0.04), and that this is mostly caused by the larger melt-pond coverage of FYI (42 vs. 23%). Also energy absorption was 50% larger in FYI than in MYI. Thus, a continuation of the observed sea-ice changes will increase the amount of light penetrating into the Arctic Ocean, enhancing sea-ice melt and affecting sea-ice and upper-ocean ecosystems.

Radiation fluxes through summer sea ice in the Arctic