Vanguard Magazine

IN ARCTIC AND SURVEILLANCE landscape of barren rock and frozen sea. Yet, there are five distinct marine oceano- graphic domains in the Canadian Arctic set among diverse topographies ranging from high mountains to flat low-lying is- lands only a few metres above sea-level. The approaches of the Labrador Sea and Davis Strait being wide and relatively deep are better suited for submerged operations whereas the Archipelago is set in a shelf sea with shallow sills. Some straits are ex- tremely narrow (less than a nautical mile), limiting options for submerged transit. Depths range from 800 metres in the ap- proaches to 30 metres and less in some channels and sounds. The Canadian Arctic can be notoriously difficult for navigation. A major aspect of this is the Arctic Ocean itself. For eight to 10 months of the year, sea ice coverage ranges from 80 to 100 per cent through- out the CAA. The northern and western boundaries can accumulate five metres or more of sea ice, and it can thicken dramati- cally as it approaches the many islands and narrow channels. While ice cover and flow can be observed easily by satellite and air- craft, ice keels are a different matter. Ice ridges and rafting create deep ice keels, posing hazards for submerged submarines and UUVs. 1 This same mobile ice is chal- lenging for shore-terminated cabling, and sensor elements/connections may even be susceptible to deep-water scouring by bergs or old ice ridges. The Arctic remains an unfavourable environment for acoustic sensors. Arctic sound velocity profiles are layered. There is a cold, fresh Arctic water layer down to roughly 60 metres. Under that are the Pa- cific and Atlantic water masses and then, if bathymetry permits, deep water. Seasonal freeze and melt processes alter salinity and density, reshaping propagation conditions. Ambient noise is high due to ice move- ment, limiting passive acoustic detection, and reverberation from under-ice reflec- tions reduces the effectiveness of active sonar. These factors complicate acoustic detection (and counter-detection) and can confuse the classification of underwater targets. GPS satellite ground tracks do not pass di- rectly over the North Pole and the satellites www.vanguardcanada.com OCTOBER/NOVEMBER 2025 19 A R C T I C Depicts degree of confidence of hydrographic survey of Canadian Arctic Archipelago. Green indicates chart coverage to modern survey standards. Yellow shows charts of adequate standard for navigation. Red indicates areas of inadequate survey (method lacks necessary accuracy). (Reproduced with the permission of the Canadian Hydrographic Service) Depicts degree of confidence of hydrographic survey of Hudson Bay, Hudson Strait, Fox Basin. Green indicates chart coverage to modern survey standards. Yellow shows charts of adequate standard for navigation. Red indicates areas of inadequate survey (method lacks necessary accuracy). (Reproduced with the permission of the Canadian Hydrographic Service)

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