| Résumé | The purpose of this four-year research project, which spans from March 2011 to March 2015, is to document the thickness and strength of hummocked multi-year ice. The first two years of the project are reported upon here. Year 1 involved designing and manufacturing customized equipment to measure the temperature, salinity and strength of 12m thick multi-year ice and using the equipment to sample a multiyear ice hummock from crest to keel. The first season of measurements was conducted in the spring 2012, on landfast multi-year ice 120km northwest of Resolute, Nunavut. Year 2 of the program was taken to plan, prepare and conduct a field program on drifting multi-year ice in the Beaufort Sea in the spring of 2013. Background is given about the three main options for accessing multi-year ice (shipbased access, community-based access and remote camps) in order to more fully appreciate the challenges and data collected during the 2012 and 2013 field seasons. Outcomes from the 2012 field program, conducted from 3 May to 20 May from Resolute, Nunavut, include: (1) field testing equipment by collecting data on the thickness, temperature and borehole strength of 1.75m thick first-year ice, (2) measuring the thicknesses at 19 holes on a hummocked multi-year ice floe that had an average thickness of 8.6 ± 1.0m, (3) measuring the temperature, salinity and strength through its full thickness of 10.8m thick ice on the shoulder of a multi-year ice hummock, (4) measuring the partial temperature and salinity profile of a hummock crest and conducting borehole strength tests through the full thickness of the 12.4m thick ice. The 2013 field program, conducted from 18 March to 7 April from Sachs Harbour, NWT, was prematurely terminated due to health and safety concerns. As a result, the program’s primary objective – measuring the strength of hummocked multi-year ice – could not be met. Nevertheless, outcomes from the 2013 field program include (1) equipment being field-tested on 1.65m thick cold, first-year ice to collect data on its temperature, salinity and borehole strength, (2) satellite tracking beacons were deployed on four, hummocked multi-year ice floes, (3) the two floes on which at least ten thickness measurements were made had an average thickness of 2.7 ± 2.2m (first-year ice) and 5.6 ± 2.5m (multiyear ice) and (4) photographic documentation of numerous substantial, deformed multi-year ice floes 150km west of Sachs Harbour. The drift trajectories of the two, hummocked multi-year ice floes on which drift trajectories are available for a period of five months clearly illustrate that some of the more significant floes encountered during the 2013 field study pose a very real hazard for structures in the southern Beaufort Sea, including the relatively near-shore Amauligak site. |
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