Surface flooding of Antarctic summer sea ice

• Published in: Annals of glaciology Vol. 61; no. 82; pp. 117 - 126
• Main Authors: Ackley, S. F., Perovich, D. K., Maksym, T., Weissling, B., Xie, H.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01-09-2020
• Subjects: Albedo; Albedo (solar); Antarctic sea ice; Buoys; Earth science; Flooding; Floods; Freezing; Freezing point; Glaciers; Heat; Heating; High temperature; Ice; Ice accumulation; Ice cover; Ice thickness; Ice/ocean interactions; Icebreakers; Mass balance; Melting; Melting points; Mixed layer; Pack ice; Precipitation; Radiative heating; Radiometers; Sea ice; sea-ice growth and decay; Seawater; Sensors; Snow; Snow accumulation; Snow and ice; Snow depth; snow/ice surface processes; Snowfall; Solar heating; Summer; Thermistors; Water temperature; Amundsen Sea; Weddell Sea; sea-ice growth and decay; sea ice; snow/ice surface processes; Ice/ocean interactions
• ISSN: 0260-3055; 1727-5644
• DOI: 10.1017/aog.2020.22

The surface flooding of Antarctic sea ice in summer covers 50% or more of the sea-ice area in the major summer ice packs, the western Weddell and the Bellingshausen-Amundsen Seas. Two CRREL ice mass-balance buoys were deployed on the Amundsen Sea pack in late December 2010 from the icebreaker Oden, bridging the summer period (January–February 2011). Temperature records from thermistors embedded vertically in the snow and ice showed progressive increases in the depth of the flooded layer (up to 0.3–0.35 m) on the ice cover during January and February. While the snow depth was relatively unchanged from accumulation (<10 cm), ice thickness decreased by up to a meter from bottom melting during this period. Contemporaneous with the high bottom melting, under-ice water temperatures up to 1°C above the freezing point were found. The high temperature arises from solar heating of the upper mixed layer which can occur when ice concentration in the local area falls and lower albedo ocean water is exposed to radiative heating. The higher proportion of snow ice found in the Amundsen Sea pack ice therefore results from both winter snowfall and summer ice bottom melt found here that can lead to extensive surface flooding.