Measurements of currents close to the bottom in the deep ocean

Abstract

Abstract Currents close to the bottom have been inferred from bottom photographs and from sand waves recorded by echo sounders. Bottom currents on the continental shelf have been measured with sea bed drifters (analogous to drift bottles for measuring surface currents). Measurements of bottom currents have also been made with current meters, and recently it has been possible to record currents for long periods. The literature and techniques are reviewed. Measurements to date suggest that strong currents (i.e., in excess of one to two-tenths of a knot) exist close to the bottom in the deep ocean in at least some areas some of the time. Details concerning the nature of the circulation are not clear, but it is possible that the deep circulation is as complex as the surface circulation.