Magnetic Field Model MF2 (lithospheric)

The magnetic field model MF2 provides the spherical harmonic (SH) coefficients of the scalar potential of the magnetic field. This second version of our series of field models is limited to degrees 16-80 (MF1: 15-80), representing the visible portion of the lithospheric field.

MF2 incorporates all available quiet time CHAMP scalar and vector data from 09-Aug-2000 to Aug-2002. The scalar data were filtered along-track by fitting and subtracting a 3-parameter subset of degree-1 internal and external dipoles. The vector data were filtered in a similar way, fitting the 11 parameters of a full degree-1 internal and degree-2 external field. The two data sets were merged giving a 3:1 weight of the scalar data over the vector data. No regularisation at all was applied to the zonal coefficients.

Above degree 40, the tesseral and sectorial coefficients were damped in order to reduce noise. All coefficients were equally rolled off to zero in the interval of degrees 76-80.


This image shows the Z-component of MF2 as predicted at the Earth's surface by spherical harmonic downward continuation. Downward continuation strongly amplifies noise. The fact that the image is nevertheless dominated by geologically justifiable small scale features indicates a considerable improvement over earlier lithospheric field models