Surface and melt pond evolution on landfast first-year sea ice in the Canadian Arctic Archipelago

The evolution of landfast sea ice melt pond coverage, surface topography, and mass balance was studied in the Canadian Arctic during May-June 2011 and 2012, using a terrestrial laser scanner, snow and sea ice sampling, and surface meteorological characterization. Initial melt pond formation was not limited to low-lying areas, rather ponds formed at almost all premelt elevations. The subsequent evolution of melt pond coverage varied considerably between the 2 years owing to four principle, temporally variable factors. First, the range in premelt topographic relief was 0.5 m greater in 2011 (rougher surface) than in 2012 (smoother surface), such that a seasonal maximum pond coverage of 60% and maximum hydraulic head of 204 mm were reached in 2011, versus 78% and 138 mm in 2012. A change in the meltwater balance (production minus drainage) caused the ponds to spread or recede over an area that was almost 90% larger in 2012 than in 2011. Second, modification of the premelt topography was observed during mid-June, due to preferential melting under certain drainage channels. Some of the lowest-lying premelt areas were subsequently elevated above these deepening channels and unexpectedly became drained later in the season. Third, ice interior temperatures remained 1-2 degrees C colder later into June in 2012 than in 2011, even though the ice was 0.35 m thinner at melt onset, thereby delaying permeability increases in the ice that would allow vertical meltwater drainage to the ocean. Finally, surface melt was estimated to account for approximately 62% of the net radiative flux to the sea ice cover during the melt season.