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GSFC (12/83) Field Model 1985

Author:
R. A. Langel
NASA/GSFC, Code 921
Greenbelt, Maryland 20771

Parameter: Earth's main magnetic field strength and vector
Availability: Retrievable from CCMC's anonymous FTP site
Brief Description:

This data set contains the 367 coefficients of the GSFC (12/83) geomagnetic field model. The coefficients are for epoch 1980.0 and extend to degree and order 14 in the constant terms and 11 in the first derivative terms. The model is based on 54,728 MAGSAT data from November 1979 through April 1980 and on data from 91 magnetic observatories for 1978 through 1982. Different from earlier MAGSAT-based models, MAGSAT vector data are only used equatorward of 50 geomagnetic latitude to avoid the effects of field-aligned currents. Poleward of 50 , only field magnitude (scalar) data are considered. Again, as for GSFC (9/80), the observatory data are corrected for crustal (anomaly) biases. The authors also provide first order external coefficients and their dependence on the magnetic disturbance index Dst. The main field terms truncated to degree 10 were adopted as the definitive IGRF for epoch 1980. GSFC (12/83) was also used to derive the definitive IGRF models for 1945, 1950, 1955, and 1960 (see International Geomagnetic Reference Field). A subroutine for calculation of geomagnetic field strength and vector components is included.

References:
R. A. Langel and R. H. Estes, The Near-Earth Magnetic Field at 1980 Determined from MAGSAT Data, J. Geophys. Res. 90, 2495, 1985.

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