EFFECT OF THE PHASE COMPOSITION OF SNOW ON THE ONSET OF AIR CONVECTION IN IT

The problem of convection onset in a snow cover of floating ice is considered. It is usually solved within the framework of the so-called single-temperature (classical) model with one heat conductivity equation, since it assumes the equality of temperatures of the liquid (air-vapor) and solid (ice) phases of snow, despite the difference in their thermal conductivities of approximately a hundred times. Here, the stability problem, apparently for the first time for snow, is studied within the framework of a more general, two-temperature model using heat conduction equations for each phase. This approach takes into account the intensity of interphase heat exchange, the difference in the thermal properties of air and ice, the porosity of snow, and the hydrological specifics of the problem. Two variants of boundary conditions corresponding to an impermeable (due to freezing of surface ice crystals) and permeable for air upper boundary are considered. Analytical solutions to the problem were obtained, their parametric study was carried out, a comparison of process estimates by one- and two-temperature models was performed as well as areas of applicability were determined. It is shown that taking into account the heat exchange of phases causes an increase in the instability threshold in comparison with the classical approach by several times. Using a thermodynamic model of snow-ice cover, which allows calculating the temperature of the snow cover boundaries based on standard meteorological observations, A comparison of the modeling data with estimates of the process characteristics for real conditions of air-sea energy exchange at the Shokalskiy Srait (Severnaya Zemlya Archipelago) was performed.