Detection of Magnetic Signals from Ocean Circulation with Satellite Altimetry and Magnetometer

Electrically conducting sea-water moves through Earth's magnetic field and generates electromagnetic signals itself. These signals can be detected by space borne Earth observation technologies, like the Swarm satellite magnetometer mission. In contrast to already successfully detected ocean tidal magnetic signatures, the magnetic signals from ocean circulation are still unidentified in observations. However, the electromagnetic signals from the ocean circulation would be an additional, interesting source of information.
We propose, that satellite altimetry can be helpful in order to detect magnetic signals from ocean circulation. Sea surface height measurements allow to estimate depth-integrated current velocities by using the geostrophic approximation, which describes a balance between sea surface height gradients and horizontal currents. With the resulting integrated electric current density, the magnetic signals from ocean circulation can be calculated using an electromagnetic induction solver. In a further step, the estimations are a basis for the  separation of magnetometer observations and for data assimilation.
Therefore, it is necessary that the geostrophic approach reflects the realistic time behavior of electromagnetic signals from ocean circulation. Ocean model data allows to verify this approach with respect to the identification of magnetic signals from ocean circulation in satellite magnetometer observations. We present this analysis and report about the feasibility of this approach regarding the Swarm mission and possible future missions.