No abstract

Ice and snow sublimation is a naturally occurring process in which the solid ice changes state to become a vapour without passing through the usual liquid stage. The sublimation of blowing snow can be critical in areas which rely on melting snow as an important source of moisture. In blowing snow, the sublimation process is influenced by air temperature, relative humidity, wind speed, net radiation and particle surface area. When pore ice sublimation occurs in an ice/sediment mixture, the process is complicated by the presence of the particles of sediment. The sublimation of frozen moisture from sediments has implications for dust production, for human safety in permafrost tunnels, and for the aeolian movement of sediments in cold environments. A limited number of studies have considered sublimation from frozen sediments and a very few of these have been done under field conditions. The variables of air temperature, relative humidity, sediment moisture content and wind speed influence the amount and rate of pore ice sublimation, but there is some disagreement as to the relative importance of these variables.

No abstract

Pore-ice sublimation is a prerequisite for aeolian activity in cold environments where surface sediments hold significant amounts of frozen water. Few quantitative studies have defined the rate of grain release from cemented surfaces by poreice sublimation. In 1996-1997, controlled field experiments at Presqu'ile Beach, Ontario, were implemented to measure sediment release from frozen surfaces. The release rates were compared to the local wind regime, ambient temperature and humidity. In additional field experiments, the effect of sediment water content on grain release by sublimation was examined. From the experimental results, an equation which predicts grain release based on local wind speed, ground temperature, humidity, and surface water content is proposed. Predicted release rates show reasonable agreement with natural deflation measured on the beach at Presqu'ile Provincial Park.