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www.the-cryosphere-discuss.net/5/1835/2011/
doi:10.5194/tcd-5-1835-2011
© Author(s) 2011. This work is distributed
under the Creative Commons Attribution 3.0 License.
Laboratory study of frazil ice accumulation under wave conditions
1Geophysical Institute, University of Bergen, Allégaten 70, 5007, Bergen, Norway
2Nansen Environmental and Remote Sensing Center/Mohn-Sverdrup Center, Thormøhlensgate 47, 5006, Bergen, Norway
Abstract. Ice growth in turbulent seawater is often accompanied by the accumulation of frazil ice crystals at its surface. The thickness and volume fraction of this ice layer play an important role in shaping the gradual transition from a loose to a solid ice cover, however, observations are very sparse. Here we analyse an extensive set of observations of frazil ice, grown in two parallel tanks with controlled wave conditions and thermal forcing, focusing on the first one to two days of grease ice accumulation. The following unresolved issues are addressed: (i) at which volume fraction the frazil crystal rising process starts and how densely they accumulate at the surface, (ii) how the grease ice solid fraction evolves with time until solid ice starts to form and (iii) how do these conditions affect, and are affected by, waves and heat loss from the ice. We obtained estimates of the initial frazil ice solid fraction (0.04–0.05), the maximum solid fraction to which it accumulates (0.24–0.28), as well as the time-scale of packing, at which 95 % of the frazil reaches the maximum solid fraction (12–18 h). Comparison of ice thickness and wave observations also indicates that grease ice first begins to affect the wave field significantly when its thickness exceeds the initial wave amplitude. These results are relevant for modelling frazil ice accumulation and freeze-up of leads, polynyas and the seasonal ice zone.
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Notice on Discussion StatusCitation: De la Rosa, S. and Maus, S.: Laboratory study of frazil ice accumulation under wave conditions, The Cryosphere Discuss., 5, 1835-1886, doi:10.5194/tcd-5-1835-2011, 2011. Bibtex EndNote Reference Manager XML
