The glider navigation system for Fram Strait employed navigation signals broadcast from 260 Hz RAFOS sources and tomographic sources (Sagen et ah, 2011; Sandven et ah, 2013).
In the Antarctic, ARGO floats are traceable at distances of up to 600 km under the ice by use of RAFOS signals at 260 Hz (Klatt et ah, 2007).
Only 8 percent of the RAFOS
floats followed the Deep Western Boundary Current, or DWBC--"a remarkably low number in light of the expectation that the DWBC is the dominant pathway for Labrador Sea Water," the researchers wrote in Nature.
When the center of the current is located, two RAFOS
floats are lowered by hand over the side, about 5 kilometers apart.
floats and current meters recently deployed as part of the World Ocean Circulation Deep Basin Experiment should be helpful in testing this hypothesis.