CGRG Bibliography of Canadian Geomorphology
Search Results
Author : Colgan, W.; Sharp, M.; and Hryciw, L.
Date : 2005.
Title : Inter-annual variability in net accumulation reconstructed from ice cores from the Devon Island Ice Cap, Nunavut.
Publication : Arctic Net 2005 Programme. Annual Scientific Meeting, December 13-16, 2005. Banff, Alberta
Issue :
Page(s) : 44.
Abstract
Three short ice cores, spanning the period 1938 to 2003, were recovered along a transect between the equilibrium line and the summit of the Devon Island Ice Cap, Nunavut. High-resolution anion (Cl–, SO4 2–, NO3 2 and methanelsulphonate (MSA)) stratigraphy was used to define annual layers in the cores, and density profiling allowed computation of the long term mean and annual net accumulation rates at each site. The three accumulation records were stacked and their principal components computed to identify regional and site-specific patterns of interannual variability. These patterns were correlated with indices of major modes of climate variability (Arctic Oscillation (AO) and El Nino Southern Oscillation (ENSO)) and with the northern hemisphere geopotential height and sea level pressure fields derived from the NCEP Reanalysis in order to identify the influence of variability in atmospheric circulation on the accumulation histories. To investigate the influence on net accumulation of variability in sea ice extent and concentration and atmospheric transport pathways to the ice cap, daily 120hr air mass back-trajectories were calculated for the period 1979-present using NCEP Reanalysis data and the Japanese METEX model. These back-trajectories indicate that northern Baffin Bay and the northeast Queen Elizabeth Islands and an adjacent segment of the Arctic Ocean are the primary air mass source areas for the Devon Island Ice Cap. However, a circumpolar band of more distant regions, as far south as 65°N, such as coastal Russia and the North Atlantic, can also act as source areas for air masses and, potentially, moisture. The flux of air masses leaving these distant source areas was found to vary significantly with the phase of the AO. Interactions between changing transport pathways to the ice cap and sea ice conditions along the transport path may be responsible for a portion of the variability in the net accumulation records. The net accumulation record shows distinct high and low periods, with highs from 1987-1992 and 1999-2002 and lows from 1981-1987 and 1993-1998. Airborne laser altimetry measurements conducted between 1995 and 2000 suggest that high elevation areas of the Devon Island Ice Cap thickened by up to 1m during this period (Abdalati et al., 2004). The reconstructed net annual accumulation rates were found to be anomalously low at all three core locations during this period, indicating that the observed thickening was probably not a result of a brief period of anomalously high net accumulation, rather more likely the result of a long-term trend involving the ice flow dynamics of the ice cap.
Bibliography of Canadian Geomorphology