Magnetic signals from an ocean eddy

Abstract

The movement of sea water in the magnetic field of Earth causes a process of motional electromagnetic induction. As a result, electric currents flow both in the sea water, and in the material of the seafloor. There has been long-standing interest in observing the magnetic fields of such motional induction, especially at periods longer than a day. Conditions appear to have been favourable for such observations during an experiment which took place in 1983/84 on continental Australia and the floor of the adjacent Tasman Sea. The particular circumstances were the passage of an active ocean eddy across a line of seafloor magnetometers and electrometers; the presence on the seafloor of a 1 km pile of porous (and thus electrically-conducting) sediments; and the simultaneous observation of magnetic fluctuations at sites remote from the eddy. -from Authors