Precision current measurements using drifting buoys equipped with Decca Navigator and Argos

A research program to study tidal processes, frontal circulation, and mixing is described. Free-floating drogued buoys which have been developed are discussed. These buoys are equipped with the Decca Navigator, a hyperbolic radio navigation system with extensive coverage in Western Europe, which is used to provide accurate and frequent fixes, and the ARGOS satellite system, which is used to monitor the progress in real time and to assist recovery. The low power consumption microprocessor-based Decca Navigator receiver designed for this application synchronizes to the precisely timed Decca transmission and then goes into sleep mode, waking briefly at 10-min intervals to take position fixes. The position data acquired are stored in a 2-Mb memory card which has a 3-month capacity at the 10-min rate. The recovery procedure and other developments are described