Electromagnetic Phenomena in Oceanic Environments

Electromagnetic phenomena in oceanic environments emerge when seawater, a conductive fluid, moves through the Earth’s magnetic field. Motional induction generates electric and magnetic fields that permeate the ocean and extend to satellite altitudes, while the spatio-temporal variability of tides and currents imprints periodic signatures on the geomagnetic field. These signals can be detected by spaceborne magnetometers, undersea voltage cables and coastal observatories. Through a combination of theoretical modelling, numerical simulations and machine learning approaches, researchers map global tidal transports, monitor large-scale circulation, infer ocean heat content and constrain Earth’s conductivity structure. Such endeavours hold promise for climate monitoring, geophysical exploration and disaster mitigation.

Research from Nature Portfolio

Recent studies have demonstrated how satellite magnetometer data can be harnessed to derive global tidal transports directly, circumventing heavy reliance on forward model constraints and improving estimates of water movement and mixing. Another investigation employed an artificial neural network to invert tidal magnetic signals for ocean heat content, yielding the first space-borne assessment of thermal anomalies and enabling insights into abyssal warming where in situ data are sparse. Both advances illustrate the potential of electromagnetic observations to complement traditional oceanographic methods.

Electromagnetic Phenomena in Oceanic Environments publication trend

The graph below shows the total number of articles in electromagnetic phenomena in oceanic environments across all publications each year (not limited to Nature Index journals).

Technical terms

Electromagnetic induction: Generation of electric currents and secondary magnetic fields when electrically conducting seawater moves through the Earth’s magnetic field.

Ocean-induced magnetic field (OIMF): Secondary magnetic field produced by ocean currents and tides interacting with the geomagnetic field.

Electrical conductivity: Measure of seawater’s capacity to carry electrical current, determined by its temperature and salinity.

Tidal magnetic signals: Periodic variations in the geomagnetic field arising from the motion of ocean tides.

Artificial neural network (ANN): Computational model inspired by biological neural architectures, used here to infer ocean heat content from electromagnetic observations.

Inversion scheme: Computational technique to derive physical properties from observed electromagnetic data.

References

1. Tidal transports from satellite observations of earth’s magnetic field. Scientific Reports (2023).
2. Estimating global ocean heat content from tidal magnetic satellite observations. Scientific Reports (2019).
3. Electrical conductivity of the global ocean. Earth, Planets and Space (2017).
4. Tide-induced magnetic signals and their errors derived from CHAMP and Swarm satellite magnetometer observations. Earth, Planets and Space (2021).
5. Can seafloor voltage cables be used to study large-scale circulation? An investigation in the Pacific Ocean. Ocean Science (2021).