Electromagnetic Coupling of Ocean Flow with the Earth System

Abstract

The ocean is electromagnetically coupled with the Earth System. This results in momentum transfer, as well as a participa- tion by the ocean in the Earth’s observable electric and magnetic fields. The coupling is typically quite weak and quantitative analyses indicate that many of these connections may be discounted when considering the transfer of momentum. But because of systematic effects there are also cases where an immediate discount is not justified and electromagnetic transfer of ocean momentum should remain within the realm of consideration. For practical considerations, even if the coupling is weak these effects are phenomenologically important because the electric and magnetic fields associated with this coupling offer an obser- vational means for inferring the ocean flow. While in situ measurements of the electric field have long been used to measure ocean transport, new opportunities for remote sensing ocean flow through ground and space magnetic observatories are now being considered. In this article a brief update of the status of these observational methods is given. Extending beyond these established elements of the ocean’s electromagnetic involvement, an attempt is made to provide a quantitative discussion of lesser considered elements of the ocean’s electromagnetic coupling with the mantle and fluid core.