Acoustically tracked passive drifters for measurement of oceanic circulation. Adaptation to the Nordic Seas

Abstract

A review of the technology to use neutrally buoyant subsurface drifters or floats for Lagrangian measurements of ocean circulation was made. Focus was put on the RAFOS technology which uses small floats that listen to low-frequency sound-transmitting sources moored at fixed positions in the deep water. Recent applications of this and similar techniques have been studied. Some suggestions for future float applications with emphasis on studies in Nordic waters are presented. These include measurement of the internal circulation in the deep basins, and the exchange of waters between them. The float technology requires close follow-up during planning and execution of experiments by the scientists involved. It is recommended in the beginning to spend most efforts on tasks related to scientific planning and performance, and less on the technological parts, by applying as much commercially available equipment as possible.