Reliable characterization of K1 and S2 ocean tidal magnetic signals from satellite observations

Determine whether oceanic tidal magnetic signals of the solar diurnal K1 and semi-diurnal S2 constituents can be reliably characterized from CHAMP and Swarm satellite magnetometer observations despite the coincidence of their periods with solar daily harmonics, by establishing a robust separation of ocean-generated magnetic signals from ionospheric and high-latitude current contributions at these frequencies.

Background

The paper successfully retrieves and validates satellite-derived magnetic signals for the M2, N2, O1, and Q1 oceanic tidal constituents using CHAMP and Swarm data, supported by 3-D electromagnetic simulations. However, constituents whose periods coincide with solar daily harmonics, notably K1 and S2, are dominated by ionospheric dynamo fields, complicating their extraction from space-based magnetometer measurements.

The authors note that reliably separating ocean tidal magnetic signals at these frequencies requires improved characterization and mitigation of ionospheric and high-latitude current effects, a challenge that remains beyond the scope of the present work and thus constitutes an unresolved problem for future investigations.