CGRG Bibliography of Canadian Geomorphology
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Author : Gardner, A.S.; and Sharp, M.J.
Date : 2006.
Title : Influence of variability in the circumpolar vortex on the mass balance of Canadian High Arctic glaciers.
Publication : Joint Annual Meeting of the Geological Association of Canada and the Mineralogical Association of Canada. University of Quebec in Montreal (UQAM) May 14-17, 2006.
Issue :
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Abstract
As part of a study of glacier-climate interactions in Arctic Canada we investigated the relationships between long-term (~40 years) mass balance records from 4 glaciers in the Queen Elizabeth Islands and indices of synoptic-scale climatic variability derived from National Centers for Environmental Prediction (NCEP) climate reanalysis fields. The summer mass balance is the dominant source of variability in the annual mass balance of these glaciers, so it is useful to compare records of annual mass balance with indices of circulation variability for the summer months (JJA). Individual glacier mass balance records are poorly correlated (r = .23-.55) but they do display strong underlying similarities that are suggestive of a large-scale climatic signal that is partly masked by local influences. Principal components analysis was applied to the four time series to extract the primary mode of variance in the four datasets. The first principal component (PC1), which accounts for 55% of the variance in the MB records, was taken to be representative of the regional climatic signal in Canadian High Arctic glacier mass balance. PC1 is significantly correlated (r = .61) with NCEP regionally averaged summer surface air temperatures. The time series of PC1 was correlated with two major indices of northern hemisphere climate, the Arctic Oscillation (AO) and the North Atlantic Oscillation (NAO), to determine whether there was any relationship between these indices and the mass balance records. There was no significant correlation with either index. An index for the intensity of the summer northern circumpolar vortex, the dominant feature of the Arctic atmospheric circulation, was therefore created by standardizing the NCEP summer 300mb geopotential heights for a 5 by 5 degree box located over the average position of the 300mb geopotential height minimum for the period 1963-2001. Variations in this index are well correlated with variations in summer atmospheric temperatures across the Canadian High Arctic, and account for 36% of the variance within the PC1. To further investigate the relationship between glacier mass balance and atmospheric variability, differences were taken between mean July atmospheric profiles of geopotential height and atmospheric temperature for extreme negative and extreme positive PC1 anomaly years. During years of highly negative glacier mass balance, 300mb geopotential heights are anomalously high, corresponding to pronounced tropospheric warming and stratospheric cooling. Whether this relationship is the direct result of changes in atmospheric green house gas concentrations still needs to be investigated.
Bibliography of Canadian Geomorphology