Voronoi Dynamics Simulation of Platelet Sea Ice Growth with Diffusive Heat and Mass Transfer

Abstract

Platelet ice is a sea ice type found near an ice shelf. Platelet crystals, which originate in the water column, rise to the surface and deposit under the sea ice cover in a loose layer forming a subice platelet layer. There they grow in the near-surface supercooled water to become frozen into the ice cover as incorporated platelet ice. Several Antarctic field campaigns have collected ice cores, measured crystallographic and physical properties and simultaneously recorded oceanographic conditions. However, some in situ measurements are difficult to acquire experimentally, in particular the solid fraction of subice platelet layer which is required in this region to obtain sea-ice thickness from remote-sensing measurements. Voronoi dynamics is a simple but efficient grain growth technique. By integrating this with mechanical stability and heat and mass transfer by diffusion, virtual ice cores are simulated in three dimensions. This model shows topological similarity with incorporated platelet ice from real sea ice cores. The calibrated spatial-temporal distributions of porosity, salinity, temperature and crystallographic c-axes are extracted and compared with the observations. The solid fraction of the subice platelet layer obtained from our simulation due to the local growth of platelet crystals within this layer is 0.22 ± 0.01. In order to account for the flux of new crystals deposited into the sub- ice platelet layer, this must be combined with a packing efficiency of the deposition of platelet crystals 0.06 ± 0.01 (Dempsey et al., 2010). The total solid fraction is 0.28 ± 0.01 which is in good agreement with 0.25 ± 0.06 reported by Gough et al. (2012)