Alpine snowpack

Pikas do not hibernate, remaining active under the alpine snowpack. They store fodder for their long winters, as large haystacks of dried forage, each about 0.25 m in volume, and typically located beneath an overhanging rock that provides shelter from the weather. 

The Alpine and maritime snowpacks have many similarities. A specific figure is not necessary here and can be found in Sturm et al, " Alpine snowpacks form in regions slightly colder than the maritime snowpack and signs of melting are less frequent. The temperature gradient in late fall can be sufficient to form a depth hoar layer 5 to 20 cm... 

At the beginning of the snow season, ground temperatures are usually close to 0°C, so that the temperature gradient is determined by the atmospheric temperature. In temperate areas with a maritime or Alpine snowpack, the temperature gradient will usually be less than 10" C.m while in subarctic or Arctic areas, it will usually be greater than 20°C.m ... 

The impact of the temperature gradient on metamorphism explains many of the features of Figure 1. The typical HGM-type metamorphism of the taiga snowpack eventually transforms most of the snowpack into depth hoar, " while the QIM-type metamorphism of the maritime and Alpine snowpacks forms, in the absence of melting, layers of small rounded grains 0.2 to 0.4 mm in diameter. However, considering the effects of other climate variables such as wind speed is necessary to explain features such as the presence of windpacks formed of small rounded grains in the tundra snowpack. 

An obvious correlation between polar and alpine environments is the decrease in temperature with increasing latitude or elevation. This temperature change leads to a shift in environmental phase distribution equilibria - i.e. a chemical moves from the atmosphere to terrestrial surfaces, including direct deposition to surface waters, but also to snowpack and soils from which movement into surface and groundwater is possible. This process has been termed cold condensation but should more correctly be called cold-trapping because the contaminants are not actually condensing. 

Brown LE, Hannah DM, Milner AM (2007) Vulnerability of alpine stream biodiversity to shrinking glaciers and snowpacks. Global Change Biol 13 958... 

Bilbrough C. J., Welker J. M., and Bowman W. D. (2000) Early spring nitrogen uptake by snow-covered plants a comparison of arctic and alpine plant function under the snowpack. Arct. Antarct. Alp. Res. 32, 404-411. 

Among several existing classifications of seasonal snowpacks, we use that of Sturm et al. " that describes the tundra, taiga, Alpine, maritime, prairie and ephemeral snowpacks. Sturm et al. also mention the mountain snowpack, that displays such large spatial variations that it... 

Since both albedo and gas adsorption depend on SSA, the climate response of the concentration of species adsorbed within the snowpack will be similar to that of albedo increase in regions where warming is accompanied by a change from HGM to QIM, such as the southern taiga and the warmer Alpine areas in the fall and decrease in the other regions. These effects will be modulated by the temperature increase, that will decrease the concentration of adsorbed species. For example, a temperature rise from -15 to -10 °C will desorb 40% of adsorbed acetone molecules, that have an adsorption enthalpy of 57 kJ/mol,, at constant SSA. The combined effect of warming and SSA change will then probably lead to a decrease in the concentration of adsorbed species in most areas. 

---