Geomagnetism

Magnetic Field Model MF4:

Central America South East Asia

MF4 is a field model representing the visible part of the crustal magnetic field. It is derived from almost 5 years of CHAMP measurements of the period 09-Aug-2000 to Apr-2005. The model is given as a spherical harmonic expansion of the scalar magnetic potential to degree 90. Coefficients 1-15 are set to zero, since these coefficients are masked by the main magnetic field with its source in the Earth's core. See also the special model for ground level: MF4x Improvements over MF3 (GFZ) inclusion of latest low-altitude CHAMP data improved calibration of CHAMP vector data improved correction for polar electrojets better elimination of data disturbed by F-Region currents Data processing scheme for the MF4 model

Available MF4 Downloads
	Type	Format	Mbyte	Ref.Radius		Contents
	SH coefficients	ASCII Table	0.2	6371.2 km		MF4 Model spherical harmonic coefficients (Schmid semi-normalized, as usual)
	Graphic	PDF	0.5	6771.2 km		Image of Bz at average satellite altitude
	Graphic	PDF	0.8	6429.2 km		Image of Bz at 50 km above surface
	Graphic	PDF	0.7	6771.2 km		Image of total intensity anomaly (dT) at 400 km altitude
	Graphic	PDF	0.7	6429.2 km		Image of total intensity anomaly (dT) at 50 km above surface
	Graphic	PDF	0.6	6471.2 km		Image of analytic signal |grad(dT)| at 100 km altitude
	Graphic	PDF	0.6	6771.2 km		Image of analytic signal |grad(dT)| at 400 km altitude
	Data grid	ASCII Listing	20	6771.2 km		15' grid of Bz at average satellite altitude
	Data grid	ASCII Listing	20	6771.2 km		Total intensity anomaly (dT) at 400 km altitude
	Data grid	ASCII Listing	20	6429.2 km		Total intensity anomaly (dT) at 50 km above surface
	Data grid	ASCII Listing	21	6471.2 km		Analytic signal |grad(dT)| at 100 km altitude
	Data grid	ASCII Listing	22	6471.2 km		Northward derivative of dT at 100 km altitude
	Data grid	ASCII Listing	22	6471.2 km		Eastward derivative of dT at 100 km altitude
	Data grid	ASCII Listing	22	6471.2 km		Downward derivative of dT at 100 km altitude
	Data grid	ASCII Listing	20	6429.2 km		15' grid of Bz at 50 km above surface
	Animation	AVI	31	6471.2 km		Simple animation of a rotating sphere with MF4 crustal anomalies using Z at 100 km altitude, exaggerated as 3D and colored; the smaller greyish structures are only bumpmap overlays of a topographic/bathymetric map. Runs in MS Powerpoint und Apple Quicktime 5.0.2, but not in MS Windows Media Player. Compression yields in a loss of image quality.
						= use with caution since noise is strongly amplified by downward continuation!

2005-Jun-12, Stefan Maus, Martin Rother.