Ice Islands 



The International Ice Patrol has monitored icebergs that drift south along the coast of 

 Labrador and into the Grand Banks of Newfoundland region since the sinking of the TITANIC in 

 April of 1912. The LC carries the icebergs that calve, or break away, from glaciers in Greenland 

 and northern Canada southward from Baffin Bay and Davis Strait. Several glaciers are capable of 

 producing icebergs that end their journey on the Grand Banks. Specifically, the Ward Hunt ice 

 shelf, the Humboldt Glacier, and the Petermann Glacier are likely sources of Ice Islands, as the 

 basin conditions seem to favor the production of large tabular icebergs with shallow draft (Robe, 

 1977). 



As defined by Bowditch, an Ice Island is a piece of glacial ice that rises roughly 1 meters 

 above the ocean's surface and has an overall thickness of about 50 meters. Often, Ice Islands will 

 have a wave-like surface, appearing ribbed from the air. The surface area of an Ice Island can 

 range from a few thousand square meters to hundreds of square nautical miles. Thusly, Ice 

 Islands are not necessarily huge, in terms of surface area, but are unusually thin and flat-topped. 



The detection and identification of Ice Islands has occurred during the last two years in the 

 region of the Grand Banks of Newfoundland. Ice Islands that drift into the Grand Banks region 

 potentially pose a greater threat to shipping and the oil and gas industry than other icebergs. The 

 relatively thin drafts of Ice Islands allow them to drift into much shallower water than an iceberg 

 of similar mass but non-tabular shape. 



The tabletops of Ice Islands present an excellent target for tags and other tracking devices. 

 The Canadian Ice Service has been using CALIBs to track very large icebergs and the ice sheet in 

 the northern reaches of the Labrador Sea for many years (Desjardins, personal communication). 

 During the 2003 ice season, IIP decided to attempt marking and tracking an iceberg for the 

 purposes of gathering data such that model testing could be done after the fact. Additionally, 

 since the skill set of actually hitting an iceberg with a tracking or marking device was last 

 employed in the 1980's, the successful tagging discussed here is a nice confirmafion that IIP can 

 sfill deploy instruments with the necessary precision. 



References 



Bowditch, N., American Practical Navigator , Pub. No. 9, 2002. 



Desjardins, L., personal communication, 2003. 



Robe. R., D. Maier, and R. Kollmeyer, Iceberg Deterioration, Nature , 267, 505-506, 1977. 



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