Journal Highlights

Going electric: Incorporating marine electromagnetism into ocean assimilation models


Having a clear multidimensional picture of Earth's oceans is crucial for understanding ocean processes and how they are evolving with climate change. Ocean knowledge is currently limited by relying on in situ data. A possible source of remote data is using the electromagnetic fields produced by the ocean and detected by geomagnetic satellites. Marine electromagnetic signals largely depend on three factors: oceanic transport, the local main magnetic field, and the electrical conductivity produced by the local salinity and temperature. Thus, how can marine electromagnetic signals be utilized to enhance the multidimensional picture of Earth's ocean circulation and state? More…

N. R. Schnepf

Editors' Highlight—Using magnetic field data to infer aspects of ocean circulation

Conductive ocean water, when it moves through Earth’s ambient magnetic field, generates secondary electric field and magnetic fields. The poloidal part of the induced magnetic field can be observed outside the ocean at remote observatories and at satellites. It then follows that the ocean flow can be sensed from magnetic observations. While magnetic fields generated by tides and tsunamis are routinely observed in satellite and ground observatory data, the ocean circulation generated magnetic field has not be observed outside the ocean. This paper does not find these signals either but it does answer a hypothetical question about whether satellite observations of ocean circulation magnetic signals can be used to improve ocean circulation models. The authors find that with a very simple noise structure in the simulated satellite data, the assimilation results up to 7% improvements in ocean flow recovery, with regional enhancements and issues. This study provides important groundwork for uniting geomagnetism and physical oceanography. The idea of using magnetic field data to infer aspects of ocean circulation in a data assimilation context is innovative and potentially very useful, given the dearth of ocean observations and the urgent need to improve our understanding of the impact of climate change on global ocean circulation.