SUBLIMATION AND AEOLIAN SAND MOVEMENT FROM A FROZEN SURFACE - EXPERIMENTAL RESULTS FROM PRESQUILE-BEACH, ONTARIO

Recent aeolian literature has indicated that sand movement can and doe s take place on frozen surfaces. The winter aeolian process is influen ced by the pore ice which binds the sand grains together and increases the surface resistance to wind action. Sublimation of the frozen mois ture provides loose grains of sand which subsequently can be entrained by the wind. Field experiments carried out on the Presqu'ile Beach, O ntario in the 1992-1993 winter provide some data on variables which af fect sand loss from frozen surfaces because of sublimation. Sand moist ure content determines the resistivity of the surface to sublimation-i nduced sand loss: frozen surfaces with higher moisture contents experi ence less sand loss. The existing literature has indicated that temper ature plays an important role in the occurrence of sublimation: higher temperatures (i.e., temperatures which are closer to 0 degrees C) res ult in higher rates of sublimation. However, the Presqu'ile experiment s show that wind speed is more strongly correlated with sublimation-in duced particle loss than temperature or relative humidity. Higher wind speeds allow sand from the surface and sublimation-produced water vap our to be removed from the area, thus providing an incentive for furth er sublimation and sand loss to take place. Information on the variabl es which affect sublimation-induced sand loss from frozen surfaces can be used to increase understanding of the processes involved in sand m ovement on frozen surfaces under subzero temperatures.