On the extraordinary snow on the sea ice off East Antarctica in late winter, 2012

• Published in: Deep Sea Research Part II: Topical Studies in Oceanography
• Main Authors: Toyota, T, Massom, R, Lecomte, O, Nomura, D, Heil, P, Tamura, T, Fraser, AD
• Format: Article in Journal/Newspaper
• Language: English
• Published: Pergamon-Elsevier Science Ltd 2016
• Subjects: Earth Sciences; Physical Geography and Environmental Geoscience; Glaciology; Antarctic; East Antarctica; Wilkes Land; Antarc*; Antarctica; aurora australis; ice core; Sea ice
• Online Access: https://doi.org/10.1016/j.dsr2.2016.02.003; http://ecite.utas.edu.au/108007

In late winter-early spring 2012, the second Sea Ice Physics and Ecosystems Experiment (SIPEX II) wasconducted off Wilkes Land, East Antarctica, onboard R/V Aurora Australis. The sea-ice conditions werecharacterized by significantly thick first-year ice and snow, trapping the ship for about 10 days in thenear coastal region. The deep snow cover was particularly remarkable, in that its average value of 0.45 mwas almost three times that observed between 1992 and 2007 in the region. To reveal factors responsible,we used in situ observations and ERA-Interim reanalysis (19902012) to examine the relativecontribution of the different components of the local-regional snow mass balance equation i.e., snowaccumulation on sea ice, precipitation minus evaporation (PE), and loss by (i) snow-ice formation and(ii) entering into leads due to drifting snow. Results show no evidence for significantly high PE in thewinter of 2012. Ice core analysis has shown that although the snow-ice layer was relatively thin, indicatingless transformation from snow to snow-ice in 2012 as compared to measurements from 2007, thedifference was not enough to explain the extraordinarily deep snow. Based on these results, we deducethat lower loss of snow into leads was probably responsible for the extraordinary snow in 2012. Statisticalanalysis and satellite images suggest that the reduction in loss of snow into leads is attributed torough ice surface associated with active deformation processes and larger floe size due to sea-iceexpansion. This highlights the importance of snow-sea ice interaction in determining the mean snowdepth on Antarctic sea ice.