CGRG Bibliography of Canadian Geomorphology
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Author : Colgan, L.; and Sharp, M.
Date : 2005.
Title : Variations in net accumulation and summer melt on Prince of Wales Icefield, Ellesmere Island, Nunavut since 1965.
Publication : 35th Annual International Arctic Workshop. March 9-12, 2005. Timms Centre for the Arts, University of Alberta, Edmonton, Alberta, Canada.
Issue :
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Abstract
As a precursor to the planned recovery of a deep ice core in 2005, two short firn cores, spanning 1965 to 2000, were recovered from northern and southern summit regions of Prince of Wales Icefield, Ellesmere Island, in 2001 and 2002. To evaluate the value of these cores as climate proxies, the cores were assessed for trends and variability in net accumulation, ice content, and d18O. These proxy records were compared to instrumental records for consistency. The cores were dated using the 1963 137Cs “bomb-layer” and annual layers defined by high-resolution d18O and anion (Cl–, SO42–, NO32 and methylsulphonate (MSA)) stratigraphy. The four major anions display temporal concentration variations that correspond to trends observed in fresh snowfall at Alert. The high-resolution of the chemical record allowed annual net accumulation to be subdivided into spring/summer (SSna, occurring between the defined spring SO42– and late summer MSA peaks), and fall/winter (FWna, the inverse) components. FWna was greater than SSna in the north core (174±71 and 127±54 mmWE/a respectively), while SSna was greater than FWna in the south core (261±171 and 183±97 mmWE/a respectively). Over the reconstructed period, FWna decreased over time in both cores, while SSna remained near constant in the north core and increased over time in the south core. Wavelet analysis revealed a six to eight year periodicity in the FWna and annual net accumulation records of the north core, which approximates the periodicity of the winter (DJF) AO index, suggesting a relationship between AO and net accumulation. The abundance of ice layers within the firn cores was used as an index of summer melt intensity. The annual ice content increased towards the present in both cores, likely indicative of regional summer warming. A drift towards more positive 18O values in the north core corroborates this warming trend. Annual ice content in the south core was inversely related to the spring (MAM) and summer (JJA) sea ice cover in both Hudson’s Bay and the Arctic Archipelago. To identify seasonal and inter-annual variations in airmass source areas, a 25-year record of daily 120-hour atmospheric back-trajectories was computed using the METEX model. Airmass source regions and sea ice observations were combined to identify potential moisture source areas for the ice cap precipitation, and their seasonal and inter-annual variability. Greenland demonstrated the strongest seasonal patterns, being traversed by airmasses more in the winter (DJF) than the summer (JJA). The inverse seasonal pattern was seen over the Arctic Ocean. Baffin Bay and the Canadian Archipelago were significant airmass and moisture source regions, but constant throughout the year. The Kara-Barents and Greenland Seas, North Atlantic, interior North America and Hudson’s Bay were insignificant and highly variable airmass and moisture source regions year to year. During negative Arctic Oscillation (AO) summers, airmasses crossed the Arctic Ocean less frequently, but crossed Baffin Bay more frequently. The inverse was seen during positive phases. The AO may influence net accumulation by affecting moisture source regions.
Bibliography of Canadian Geomorphology