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.

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    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.
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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.

Item Type: Thesis (Masters)
URI: http://research.library.mun.ca/id/eprint/5523
Item ID: 5523
Additional Information: Bibliography: leaves 139-143.
Department(s): Humanities and Social Sciences, Faculty of > Geography
Date: 1980
Date Type: Submission
Geographic Location: Canada--Alberta--Payto Glacier
Library of Congress Subject Heading: Synoptic climatology--Alberta--Peyto Glacier; Glaciers--Alberta--Peyto Glacier; Peyto Glacier (Alta.)

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