Current measurement by using Doppler log.

Abstract

A new method of current measurement on shipboard by using acoustic Doppler log, can describe a detailed current structure both in horizontally and vertically. In comparison with traditional GEK (Geomagnetic Electro Kinetograph), this method has several advantages of capability to measure a current velocity, 1) without towing electrodes, 2) without change of ship's course, 3) at subsurface layers, and 4) in a shallow water region at depths of a few hundred meters, or in low-latitude area near the magnetic equator. In 1984 and 1985, current observations were made with the Doppler log system ( 130 kHz, 3 beams) installed on S/V Takuyo as a ship speed meter. Obtained current profiles in each observation are reasonable. From such a good result, it is recognized that new method is useful and would be widely used instead of GEK.