Magnetic Field Model MF6


Fig.1: (click to enlarge) Fig. 1: Vertical component of the MF6 crustal magnetic field at the Earth surface, overlain with the isochrons of an oceanage model inferred from independent marine and aeromagnetic data by Muller et al. (2007) and plate boundaries by Bird (2003). 

A cautionary note on "ringing" in satellite crustal maps: To completely get rid of the bubbliness one can apply a Hanning Window in the wavenumber domain, but at the cost of a significant loss in smallscale features (see Figure 2). As a general recommendation, one should use the unfitered version (sharp cutoff) when substituting a long wavelength satellite model into a regional magnetic compilation of marine or aeromagnetic measurements, and the Hanningwindowed version when displaying the satellite model standalone. The table of products below includes Hanningfiltered versions of the grids of the anomaly of the total intensity at ellipsoid and 50 km altitude. 

Fig.2: (click to enlarge) Fig. 2: Demonstration of the effect of the Hanning window. The left image shows the anomaly of the total intensity (dT) at 50 km altitude as given by MF6 with a sharp cutoff in the degreeband 120130. The right image shows the result after applying a Hanning window to the MF6 spherical harmonic coefficients. 
Available MF6 Downloads  

Type  Format  Mbyte  Ref. Radius  Contents  
SH coefficients  ASCII Table  0.2  6371.2 km  MF6 Model spherical harmonic coefficients (Schmid seminormalized, as usual) 

Poster  13  WGS84  MF6 model poster at AGU conference, San Francisco, 2007  
Article  4.8  Sixth generation lithospheric magnetic field model from CHAMP satellite magnetic measurements  
Graphic  1.7  WGS84  Image of vertical component (Z) at WGS84 ellipsoid altitude.  
Listing  ZIP  42  WGS84  MF6_Z_0.xyz.gz 6 arc minute ascii grid of vertical component (Z) at WGS84 ellipsoid altitude. 

Graphic  1.8  WGS84  Image of the anomaly of total intensity at WGS84 ellipsoid altitude.  
Listing  ZIP  6  WGS84  MF6_dT_0.xyz.gz 15 arc minute ascii grid of the anomaly of total intensity at WGS84 ellipsoid altitude. 

Listing  ZIP  24  WGS84  MF6_dT_0_Hanning.xyz.gz 7.5 arc minute ascii grid of the anomaly of total intensity at WGS84 ellipsoid altitude, after applying a Hanning window to the MF6 coefficients. 

Listing  ZIP  24  WGS84 + 50 km  MF6_dT_50.xyz.gz 7.5 arc minute ascii grid of the anomaly of total intensity at 50 km altitude above the WGS84 ellipsoid. 

Listing  ZIP  24  WGS84 + 50 km  MF6_dT_50_Hanning.xyz.gz 7.5 arc minute ascii grid of the anomaly of total intensity at 50 km altitude above the WGS84 ellipsoid, after applying a Hanning window to the MF6 coefficients. 

Graphic  1.5  WGS84 + 350 km  Image of the anomaly of total intensity at 350 km altitude.  
Listing  ZIP  4  WGS84 + 350 km  MF6_dT_350.xyz.gz 15 arc minute ascii grid of the anomaly of total intensity at 350 km altitude. 

Video  MPEG  50  WGS84 + 50 km  MF6_Z_50.mpg Rotating globe animation of the vertical component of the crustal field at 50 km altitude. 