Snow cover over sea ice is an important, under-reported measure during the dark cold Arctic Winter.
Snow is an excellent thermal insulator. When snow covered, sea ice attains thermodynamic equilibrium with the atmosphere when it is much thinner than bare sea ice. Alternatively, snow-covered sea ice will grow to the same thickness only if the atmosphere is much colder.
We know from the 80N temperature plot this Winter that the atmosphere WAS not much colder, in fact it was warmer than normal except for the period spanning Feb/Mar with high winds, which tends to scour the surface of warm air by mixing in higher colder layers.
Additionally, the Feb/Mar break-up event itself argues that the sea was not as strong as in past years, which may indicate that it's thickness was reduced.
Two important results will come out in May. First will be the report from NASA Icebridge, which flew at least two missions over the Beaufort sea in late March. Second is the scheduled public release of AMSR2 Level-2 data, which includes 'Snow-over-sea-ice' data.
Looking forward to this analysis since I think it will be quite useful for prediction as the 2013 melt season progresses.