A One-Dimensional Model for the Annual Snow-Firn Layer Structure

The annual layers at all depth horizons are found in ice cores from different glaciers. The formation of such layers starts at the upper part of glaciers where snow interacts with atmosphere. Here we present a one-dimensional model that describes the annual layer formation. In our model firn is performed as an ice skeleton with pore spaces. The sceleton is constructed from cubic packed spherical ice grains. The fresh snow layers are compressed under the weight of upper layers and due to metamorphism. Melted in warm seasons water permeates to the deeper cold horizons and re-freezes on the ice grains. All these processes lead to the pore space vanishing and ice layer formation. Short wave radiation penetrates to the snow depth and initiates internal melting. The top and bottom melting fronts spread up and down. Melted water decreases the snow albedo and intensifies melting. The interaction with atmosphere is taken into account through the surface heat budget. The snow surface temperature depends on atmosphere parameters such as wind speed, specific humidity, atmosphere pressure and temperature. The 15 year integration forced by climate fields from station #42020 World Meteorological Organization of year 1994 results in snow firn layers with well distinct annual structure characterized by different melt feature index. These results allow establishing a connection between the mean annual air temperature and the melt feature index.