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

• Published in: Annals of Glaciology
• Main Authors: Hutchings, Jennifer K., Heil, PÌ€etra, Lecomte, Olivier, Stevens, Roger P., Steer, Adam D., Lieser, Jan L.
• Other Authors: UCL - SST/ELI - Earth and Life Institute
• Format: Article in Journal/Newspaper
• Language: English
• Published: International Glaciological Society 2015
• Subjects: Antarctic; East Antarctica; Annals of Glaciology; Antarc*; Antarctica; Sea ice
• Online Access: http://hdl.handle.net/2078.1/172990; https://doi.org/10.3189/2015AoG69A814

Remotely sensed derivation of sea-ice thickness requires sea-ice density. Sea-ice density was estimated with three techniques during the second Sea Ice Physics and Ecosystem experiment (S1PEX-I1, September-November 2012, East Antarctica). The sea ice was first-year highly deformed, mean thickness 1.2 m with layers, consistent with rafting, and 6-7/10 columnar ice and 3/10 granular ice. Ice density was found to be lower than values (900-920 kg m-3 used previously to derive ice thickness, with columnar ice mean density of 870kg m-3. At two different ice stations the mean density of the ice was 870 and 800 kg m-3, the lower density reflecting a high percentage of porous granular ice at the second station. Error estimates for mass/volume and liquid/solid water methods are presented. With 0.1 m long, 0.1 m core samples, the error on individual density estimates is 28kgm-3 Errors are larger for smaller machined blocks. Errors increase to 46kgm-3 if the liquid/solid volume method is used. The mass/volume method has a low bias due to brine drainage of at least 5%. Bulk densities estimated from ice and snow measurements along 100 m transects were high, and likely unrealistic as the assumption of isostatic balance is not suitable over these length scales in deformed ice.