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

Stenning, Alison J. (1980) Synoptic controls on Katabatic layer characteristics above a temperate alpine-type glacier: Peyto Glacier, Alberta. Masters thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (62MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

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.

Actions (login required)

View Item