Abstract
We present a 700 km airborne electromagnetic survey of late-spring fast
ice and sub-ice platelet layer (SIPL) thickness distributions, from
McMurdo Sound to Cape Adare, providing a first-time inventory of
thickness close to its annual maximum. The overall modal consolidated
ice (including snow) thickness was 1.9 m, less than its mean of 2.6±1.0
m. Our survey was partitioned into level and rough ice, and SIPL
thickness was estimated under level ice. Although results show a
prevalence of level ice, with a mode of 2.0 m and mean of 2.0±0.6 m,
rough ice covered 41% of the transect by length, 50% by volume, with a
mode of 3.3 m and mean of 3.2±1.2 m. The thickest 10% of rough ice was
almost 6 m on average, and a 2 km segment in Moubray Bay had a thickness
greater than 8 m, demonstrating the overwhelming influence of
deformation against coastal features. The fast ice was thus
significantly thicker than adjacent pack ice. The presence of a
significant SIPL was observed in Silverfish Bay, offshore Hells Gate Ice
Shelf, New Harbour, and Granite Harbour where the SIPL transect volume
was a significant fraction (0.30) of the consolidated ice volume. The
thickest 10% of SIPLs had an average thickness of nearly 3 m, and near
Hells Gate Ice Shelf the SIPL was almost 10 m thick, implying vigorous
heat loss to the ocean (~ 90Wm-2). We
conclude that polynya-induced deformation and interaction with
continental ice influence fast ice thickness in the western Ross Sea.