Synoptic controls on Katabatic layer characteristics above a temperate alpine-type glacier : Peyto Glacier, Alberta

• Main Author: Stenning, Alison J., 1957-
• Other Authors: Memorial University of Newfoundland. Dept. of Geography
• Format: Thesis
• Language: English
• Published: 1980
• Subjects: Synoptic climatology > Alberta > Peyto Glacier; Glaciers > Alberta > Peyto Glacier; Peyto Glacier (Alta.); Alta; Canada; Newfoundland studies; University of Newfoundland
• Online Access: http://collections.mun.ca/cdm/ref/collection/theses2/id/65753

Thesis (M.Sc.)--Memorial University of Newfoundland, 1981. Geography Bibliography: leaves 139-143. Previous glacier microclimatological research has emphasized the need for further study of synoptic scale controls on boundary and katabatic layer development. A better understanding of the influence of changing synoptic conditions on the characteristics of the near-glacier air layer should lead to more accurate prediction of the surface energy balance. - A subjective ‘features of circulation’ type synoptic classification is proposed which is used to physically explain variations in wind, temperature and stability conditions in the near-surface layer. Wind and temperature profiles were obtained during the summer of 1979 at a site on the tongue of Peyto Glacier, Alberta. - The katabatic layer was found to be most strongly developed under anticyclonic conditions, with frequent occurrence of a low level wind velocity maximum and associated thermocline. These conditions favoured steady down-glacier flow, strong surface-based temperature inversions and high stability. A weak positive correlation was found between the katabatic wind velocity and surface inversion strength. Diurnal variation in surface inversion strength was most pronounced under anticyclonic influence. - Cyclonic synoptic conditions were found to result in considerable disturbance of the near-surface air layer, resulting in weaker inversions, lower stability and more variable low-level wind direction. Deviations in the direction of the surface wind were strongly influence by the direction of 700 mb flow. The geostrophic wind direction also affected near-surface temperature and stability conditions. A down-glacier flow, reinforcing the katabatic wind was associated with greater stability and inversion strength. A geostrophic wind directed perpendicular to the glacier fall-line caused considerable disturbance of wind and temperature conditions in the near-glacier air layer. The katabatic force was found to exceed the synoptic scale pressure gradient force under all synoptic conditions encountered, and to be greatest under anticyclonic conditions. - Local microclimatological studies emphasized the importance of differences in elevation, slope, aspect and proximity to ice-free areas. Greatest contrasts in temperature and wind conditions occurred under anticyclonic conditions. Turbulence in marginal ice areas may prevent the formation of a recognizable katabatic layer. Significant changes in radiation receipt around sunrise and sunset were found to result in modification of near-surface conditions.