Extraction of Tidal Signals from the Geomagnetic Field with Adapted Basis Functions.

The ocean tides generated by the solar and lunar gravity fields cause a periodic motion of conducting sea water. Due to the ambient main magnetic field, these tides eventually generate an additional contribution to the geomagnetic field measured by recent satellite missions. Since the periodicity of these tidal constituents is very well known, one is able to distinguish them from other already modeled contributions of the overall field. We use the Regularized Orthogonal Functional Matching Pursuit to extract the dominant semidiurnal lunar M2 tidal signal from set of satellite measurements.For that purpose, we use a particular collection of tailored basis functions which are spatially localized and additionally satisfy the underlying Maxwell equations.