Climatic and geographic patterns in snow density dynamics, Northern Eurasia

A body of data on snow density at different phases of snow-cover formation, in different areas provided the basis for building a model accounting for variation of snow density with the most essential factors. The obtained equation shows that the snow density increases with snow depth, snow-cover period, and mean January air temperature. The most intensive is the change of the snow density with air temperature variation in the range from -2 to -10 degrees C. Within the range of -10 to -25 degrees C, the snow density varies slightly, and below -25 degrees C the changes in temperatures do not cause marked changes in snow density. Spatial distribution of snow-cover density background values in North Eurasia is given. The scheme presented shows that there are two regions where the density of the snow cover is very low and does not exceed 0.15 to 0.18 g cm(-3). One of them encompasses central Yakutia and northern Transbaikal regions; the other covers Inner Mongolia. These regions are characteristic of extremely continental climate with shallow snow cover and low winter air temperatures. Snow density is substantially affected by orography of the terrain, which complicates the zonal patterns in variability of meteorological parameters. Zones with elevated density of the snow cover are apparent in the Caucasus, in mountain systems of Siberia, the Far East, and Middle Asia. The obtained model accounts for climato-geographical patterns in space-and-time variability of snow density over the territory of Northern Eurasia and can be used for coarse estimation of snow density in the areas with insufficient experiimental data.