IMPACT OF ARCTIC LAND FAST-ICE GROWTH ON SUBSEA GROUND FREEZING

摘要

A conceptual thermodynamic model of seasonal freezing of water column and underlying layer of bottom sediments, which is based on the solution of heat- and mass transfer equations in saline porous media, was elaborated. This model uses two distinct methods, simulating phase transitions in water and ground layers. Using realistic atmospheric forcing observed at Tiksi Polar Station during the cold season (October-May) 2009-10, land fast-ice and sub-water ground freezing was simulated in the Buor-Khaya Bay (coastal region of the Laptev Sea). Model simulations showed that the distinguished feature of ice formation at shallow depths (＜3m) is a stabilization of ice thickness caused by sub-ice layer salinization. Salinity increase in these zones exceeds an order of magnitude in comparison with the initial salinities (i.e. before freezing) and reaches ～800 psu. Convective mixing, induced by fast-ice growth, formed uniform sub-ice water layer that remains at the freezing point temperatures. As a consequence of contact of the ground with cold and saline waters, ice formation starts in the bottom sediment layer. In spite of multiple simplifications the model showed relatively good agreement with experimental data obtained by bottom drilling at the Laptev Sea shelf.