A model for entrainment of sediment into sea ice by aggregation between frazil-ice crystals and sediment grains
Abstract:A vertical numerical model has been developed that simulates tank experiments of sediment entrainment into sea ice. Physical processes considered were:turbulent vertical diffusion of heat, salt, sediment, frazil ice and their aggregates; differential growth of frazil-ice crystals; secondary nucleation of crystals; and aggregation between sediment and ice. The model approximated the real size distribution of frazil ice and sediment using five classes of each. Frazil crystals (25 m to 1.5 cm) were modelled as discs with a constant thickness of 1/30 their diameter. Each class had a constant rise velocity based on the density of ice and drag forces. Sediment grains (1-600 m) were modelled as constant density spheres, with corresponding sinking velocities. The vertical diffusion was set constant for experiments based on calculated turbulent rms velocities and dissipation rates from current data. The balance between the rise/sinking velocities and the constant vertical diffusion is an important feature of the model. The efficiency of the modeled entrainment process was estimated through α, an aggregation factor. Values for & alpha; are in the range 〈0.0003, 0.1〉, but average values are often close to 0.01. Entrainment increases with increasing sediment concentration and turbulence of the water, and heat flux to the air.
Document Type: Research Article
Publication date: 2002-01-01
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- The Journal of Glaciology is published six times per year. It accepts submissions from any discipline related to the study of snow and ice. All articles are peer reviewed. The Journal is included in the ISI Science Citation Index.
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