Brief Description:
This software package contains the International
Geomagnetic Reference Field (IGRF, Revision 1995) from 1945 to 1995/2000, the field
calculation subroutine FELDG, and the L-shell calculation
subroutine SHELLG. The IGRF models represent the Earth's main field
without external sources. They use a spherical harmonics expansion of the
scalar potential in geocentric coordinates.
The NSSDC program BILCAL produces tables of geomagnetic field strength and vector, declination, inclination, dipole moment, L-value, and field strength at the magnetic equator. As a variable, one can choose latitude, longitude (geodetic), altitude, or year (1945-1990).
The subroutines FELDG and SHELLG were developed by Kluge (1972) at the European Space Operations Centre (ESOC). His field (FELDG) and L calculation (SHELLG) uses inverse Cartesian coordinates. This method simplifies the B and L computation and reduces the required computer time by a factor of 10 in comparison with earlier calculation schemes. Kluge's SHELLG was corrected so that it now takes account of the secular changes in magnetic dipole moment.
Availability: (1) from NSSDC's Request Office on diskette for use on PCs; (2) retrievable from NSSDC's anonymous FTP site; (3) can be run via the WWW.
NSSDC ID: MG-14G
References:
G. Kluge, Direct Computation of the Magnetic Shell Parameter, Comp. Phys.
Comm., 3, 31-35, 1972.
Go to the Geomagnetic Field Models index Go to the Space Physics Models page
NASA Official: Dr. Robert McGuire, Head of the Space Physics Data Facility