Through the efforts of ASL, submarines are provided with special equipment that allows them to operate under the ice canopy.
The presence of an overhead ice canopy changes the methods by which the submarines communicate, navigate and maintain their habitability.
Johnson sets forth a far more detailedexplanation in his September 1986 "Global Heat Balance with a Liquid Water and Ice Canopy
and to map the underside of the ice canopy
, which we've been doing as we come across the pack ice," said Royal Navy Cdr Iain Breckenridge, commanding officer of HMS Tireless.