The Magnetic Signatures of the M₂, N₂, and O₁ Oceanic Tides Observed in Swarm and CHAMP Satellite Magnetic Data

This paper reports on new results in the determination of magnetic signals produced by oceanic tides as estimated from satellite magnetic measurements. We find that combining data from the past CHAMP (2000–2010) and the present Swarm (since 2013) satellite missions significantly improves the quality of the extracted tidal signals, in particular if along‐track and cross‐track magnetic “gradient” data are utilized.

This allows us to determine the magnetic signature not only of the M2 tide but also of the much weaker N2 and O1 tidal constituents. To minimize disturbances from magnetospheric and ionospheric currents, we only use data from the nightside region during geomagnetic quiet conditions and remove core, crustal, and magnetospheric field contributions as given by the CHAOS geomagnetic field model.

Despite their small magnitudes, all determined tidal constituents show sensitivity to the electrical conductivity profile of the underlying mantle, enabling imaging the upper mantle below the oceans.