Ice Island Deterioration in the Canadian Arctic: Rates, Patterns and Model Evaluation

Abstract

Knowledge regarding the deterioration processes of large tabular icebergs, known as ice islands, is limited within the Canadian Arctic. This study analyzed ice island deterioration through two aspects: 1) horizontal (areal) and 2) vertical (surface melt or 'ablation'). Satellite images were digitized to monitor areal dimensions, classify deterioration modes and correlate deterioration rates with environmental variables. The rates of deterioration were different between the Eastern and Western Canadian Arctic regions possibly due to differences in air temperature and sea ice concentration. Validation of operational surface ablation models was also carried out with in-situ microclimate measurements. The Canadian Ice Service iceberg model under-predicted surface ablation by 68%, while a more complete energy-balance model developed for ice islands improved output accuracy (7.5% under-prediction). These analyses will provide useful knowledge regarding the deterioration process of ice islands to offshore stakeholders for mitigation of risks associated with ice island hazards to offshore operations.iii

Ice island variability in polarimetric Synthetic Aperture Radar: An exploratory analysis to improve detection and ice classification

“…Ice islands are large tabular icebergs that calve from thick ice shelves and floating glacier tongues that have increased in prevalence in Arctic waters over the last decade (Crawford, 2013). There are two major source areas for Arctic ice islands: ice shelves along the northern coast of Ellesmere Island and the large outlet glaciers of NW Greenland.…”

“…25 Figure 2.9: Typical ice island drift tracks follow primary ocean currents (Crawford, 2013). There is no lower limit to ice island size, but it could be considered to be approximately 300 -400 m in length, when separation from icebergs becomes difficult (Jeffries and Sackinger, 1990).…”

“…Aside from changing sea ice, temperature increases have also been associated with an accelerated period of calving of the ice shelves at the northernmost coastline in the Canadian Arctic (Crawford, 2013). Ice shelves are thick, 5000 year-old ice that are attached to the coast and floating upon the ocean (Jeffries, 2002).…”

“…Ice shelves can accumulate mass via snowfall on their upper surface, ice accretion on their undersides and also from glacial inflow (White et al, 2015). However, in recent decades there has been almost continual vertical ablation both on their top and bottom surfaces as well as horizontal loss along the seaward and landward edges of the ice shelf (Copland et al, 2007;Crawford, 2013;Mortimer et al, 2012;White et al, 2015). Arctic ice shelves and floating glacial tongues disintegrate into large tabular icebergs termed "ice islands" (Hattersley-Smith, 1962;Koenig et al, 1952).…”

“…More recent calvings from Petermann in 2010 and 2012 have also increased the total ice islands in the Arctic Ocean (Environment Canada, 2013;Falkner et al, 2011). Large ice islands have historically survived as long as a decade or more (Cotell, 1960;Koenig et al, 1952), and fragment into smaller pieces which themselves can be hazards (Crawford, 2013). The increase in marine traffic (Judson, 2010), combined with a higher prevalence of ice hazards such as ice islands (Crawford, 2013), suggests an increased risk of vessel damage and release of hazardous cargo into the sensitive Arctic environment.…”