========================================================================= National Space Science Data Center Data set MG-14G ========================================================================= NAME: International Geomagnetic Reference Field - 10th Generation SOURCE: Susan Macmillan British Geological Survey West Mains Road Edinburgh EH9 3LA, UK Tel: +44 131 650 0228 Fax: +44 131 668 4368 email: smac@bgs.ac.uk Stefan Maus Colorado Institute for Research in the Environmental Sciences National Geophysical Data Center 325 Broadway Boulder, CO 80305-3328 USA Tel: +1 303 497 6522 Fax: +1 303 497 6513 NSSDC CONTACT: D. Bilitza, GSFC/NSSDC code 633/Raytheon, Greenbelt, MD 20771, Fax. (301) 286-1771 bilitza@mail630.gsfc.nasa.gov CONTENT: this file AAREADME.DOC FORTRAN source code: main program (interactive driver) BILCAL.FOR subroutines, functions SHELLIG.FOR BILCAL user manual with examples BILCAL.LOG All in one subroutine igrf_sub.for This file includes SHELLIG.FOR and also a subroutine igrf_sub that computes IGRF parameters. geomagnetic field model coefficients: for 1945 DGRF45.DAT for 1950 DGRF50.DAT for 1955 DGRF55.DAT for 1960 DGRF60.DAT for 1965 DGRF65.DAT for 1970 DGRF70.DAT for 1975 DGRF75.DAT for 1980 DGRF80.DAT for 1985 DGRF85.DAT for 1990 DGRF90.DAT for 1995 DGRF95.DAT for 2000 DGRF00.DAT+ for 2005 IGRF05.DAT+ extrapol. coeff. for 2005-2010 IGRF05S.DAT + The original IGRF files include coefficients up to order 13. We only use coefficients up to order 10 like in the earlier model generations. The full set of coeffients is in files IGRF00full.DAT and DGRF05full.DAT. Use of the full set requires changes to the software. BRIEF DESCRIPTION: The International Geomagnetic Reference Field (IGRF) model is the empirical representation of the Earth's magnetic field recommended for scientific use by the International Association of Geomagnetism and Aeronomy (IAGA). The IGRF model represents the main (core) field without external sources. They employ the usual spherical harmonics expansion of the scalar potential in geocentric coordinates. The IGRF model coefficients are based on all available data sources including geomagnetic measurements from observatories, ships, aircrafts and satellites. The model consists of coefficient sets from epoch 1945 onward in steps of 5 years and the first time derivatives of the coefficients for a 5-year extrapolation into the future. During the 5-year intervals between consecutive models, linear interpolation is recommended. The IGRF homepage provides access to coefficient files back to 1900. The files up to 1995 provide coefficients up to order 10, for 2000 and 2005 coefficients up to order 13 are provided. Our calculations are limited to using coefficients up to order 10 for all files. In combination with the IGRF coefficient sets different subroutines have been used to determine the components of the magnetic field vector and the L-value at a given location. The NSSDC version uses the subroutines FELDG (magnetic field vector) and SHELLG (L shell) developed by G. Kluge at the European Space Operations Center (ESOC). His use of inverse cartesian co- ordinates simplifies the computation. The IGRF subroutines were developed by A. Zunde of the U.S. Geological Survey (USGS). The program BILCAL produces tables of the geomagnetic field strength, vector components (B-abs., B-north, B-east, B-down, declination, inclination), equatorial/minimum field strength (B0), dipole moment, and L-value in latitude, longitude (geodetic), altitude, or year (decimal). Before using the IGRF please read the 'Health Warning' at http://www.ngdc.noaa.gov/IAGA/wg8/igrfhw.html AVAILABILITY: (1) FORTRAN source code from this directory. (2) Model parameters can be computed and plotted online on IGRFWeb at http://nssdc.gsfc.nasa.gov/space/model/ . (3) Model homepage at http://www.ngdc.noaa.gov/IAGA/wg8/wg8.html . REFERENCES: Peddie, N. W., International Geomagnetic Reference Field: the third generation, J. Geomagn. Geoelectr. 34, 309-326, 1982. Kluge, G., Direct computation of the magnetic shell parameter, Computer Phys. Communications 3, 31-35, 1972. International Geomagnetic Reference Field Revision 1987, J. Geomag. Geoelectr. 39, 773-779, 1987 and EOS Trans. 69, 559, 1988 Langel, R. A., D. R. Barraclough, D. J. Kerridge, V. P. Golovkov, T. J. Sabaka, and R. H. Estes, Definitive IGRF models for 1945, 1950, 1955, and 1960, J. Geomag. Geoelectr. 40, 645-702, 1988 Langel, R. A., International Geomagnetic Reference Field, 1991 Revision, J. Geomag. Geoelectr. 43, 1007-1012, 1991 Barton, C.E., Revision of International Geomagnetic Reference Field Released, EOS Trans. 77, #16, April 16, 1996. Barton, C.E., International Geomagnetic Reference Field: The Seventh Generation, J. Geom. Geoelectr. 49, 123-148, 1997. Earth, Planets, and Space Journal, Vol. 52, No. 12, pp. 1117-1233, 2000 M. Mandea et al., International Geomagnetic Reference Field - Epoch 2000 Revision Of The IGRF for 2000 - 2005, http://www.ngdc.noaa.gov/IAGA/wg8/igrf.html, 26 May 2000. International Geomagentic Reference Field - 2000, AGU EOS Transactions, pp. 347, Aug 3, 2001 ========================================================================= National Space Science Data Center Data set MG-14G =========================================================================