Comparing methods of measuring sea-ice density in the East Antarctic

• Published in: Annals of Glaciology
• Main Authors: Hutchings, JK, Heil, P, Lecomte, O, Stevens, R, Steer, A, Lieser, JL
• Format: Article in Journal/Newspaper
• Language: English
• Published: International Glaciological Society 2015
• Subjects: Earth Sciences; Physical Geography and Environmental Geoscience; Glaciology; Antarctic; East Antarctica; Annals of Glaciology; Antarc*; Antarctica; Sea ice
• Online Access: https://doi.org/10.3189/2015AoG69A814; http://ecite.utas.edu.au/98027

Remotely sensed derivation of sea-ice thickness requires sea-ice density. Sea-ice densitywas estimated with three techniques during the second Sea Ice Physics and Ecosystem eXperiment(SIPEX-II, SeptemberNovember 2012, East Antarctica). The sea ice was first-year highly deformed,mean thickness 1.2m with layers, consistent with rafting, and 67/10 columnar ice and 3/10 granularice. Ice density was found to be lower than values (900920 kgm3 used previously to derive icethickness, with columnar ice mean density of 870 kgm3. At two different ice stations the mean densityof the ice was 870 and 800 kgm3, the lower density reflecting a high percentage of porous granular iceat the second station. Error estimates for mass/volume and liquid/solid water methods are presented.With 0.1m long, 0.1m core samples, the error on individual density estimates is 28 kgm3. Errors arelarger for smaller machined blocks. Errors increase to 46 kgm3 if the liquid/solid volume method isused. The mass/volume method has a low bias due to brine drainage of at least 5%. Bulk densitiesestimated from ice and snow measurements along 100m transects were high, and likely unrealistic asthe assumption of isostatic balance is not suitable over these length scales in deformed ice.