Geomagnetism

Magnetic Field Model MF6

Satellites in low-Earth orbit (LEO) provide the most effective means of mapping the long wavelengths of the magnetic field caused by the magnetization of the Earth's crust. The first global magnetic anomaly maps were produced from POGO (1960s) and Magsat (1979) satellite measurements. A breakthrough in resolution and accuracy was achieved with the CHAMP satellite, launched in July 2000. Apart from an order of magnitude improvement in magnetometer accuracy, CHAMP was designed to remain in LEO for many years, leading to excellent spatial coverage. The MF6 model was produced using a new scalar data product from the latest three years of measurements from the CHAMP flux-gate magnetometer. The modeling methodology remained largly unchanged from the previous version MF5. MF6 resolves the crustal magnetic field to spherical harmonic degree 120, corresponding to length scales down to 333 km. The MF6 model is the first satellite-based magnetic model to resolve the direction of oceanic magnetic lineations, revealing the age structure of oceanic crust (Fig. 1).

Fig. 1: Vertical component of the MF6 crustal magnetic field at the Earth surface, overlain with the isochrons of an ocean-age model inferred from independent marine and aeromagnetic data by Muller et al. (2007) and plate boundaries by Bird (2003). Click image for higher resolution.

Available MF6 Downloads
	Type	Format	Mbyte	Ref. Radius	Contents
	SH coefficients	ASCII Table	0.2	6371.2 km	MF6 Model spherical harmonic coefficients (Schmid semi-normalized, as usual)
	Poster	PDF	13	Geoid	MF6 model poster at AGU conference, San Francisco, 2007
	Article	PDF	4.8		Sixth generation lithospheric magnetic field model from CHAMP satellite magnetic measurements
	Graphic	PDF	1.7	Geoid	Image of vertical component (Z) at geoid altitude.
	Listing	ZIP	42	Geoid	MF6_Z_0.xyz.gz 6 arc minute ascii grid of vertical component (Z) at geoid altitude.
	Graphic	PDF	1.8	Geoid	Image of the anomaly of total intensity at geoid altitude.
	Listing	ZIP	6	Geoid	MF6_dT_0.xyz.gz 15 arc minute ascii grid of the anomaly of total intensity at geoid altitude.
	Graphic	PDF	1.5	Geoid + 350 km	Image of the anomaly of total intensity at 350 km altitude.
	Listing	ZIP	4	Geoid + 350 km	MF6_dT_350.xyz.gz 15 arc minute ascii grid of the anomaly of total intensity at 350 km altitude.

2007-Dec-19, Stefan Maus