著者

R. A. LANGEL T. J. SABAKA R. T. BALDWIN

出版者

Society of Geomagnetism and Earth, Planetary and Space Sciences

雑誌

Journal of geomagnetism and geoelectricity (ISSN:00221392)

巻号頁・発行日

vol.44, no.9, pp.745-767, 1992 (Released:2010-09-14)

参考文献数

17

被引用文献数

4 3

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All available magnetic data from observatories, satellites, repeat station measurements, and aeromagnetic, shipborne and land surveys are used to derive spherical harmonic models of the geomagnetic field from 1970 to 1990. Two models are derived, one using data from the DE-2 satellite the other not, since the quality of that data is unknown. These models are designated GSFC (11/90) D and GSFC (11/90) respectively. Main field coefficients are determined up to degree 13 and temporal variation, represented by B-splines, up to degree 10. Bias values at the fixed observatories were included as part of the solution. The secular variation models are smoothed by use of norm minimization. Both models fit the data very well.The resulting secular variation shows a jerk-like trend change in several coefficients near 1979.Candidate DGRF 1985 and IGRF 1990 models are extracted from the more general models by projecting to the desired epoch and using a truncated version of the main field spherical harmonic coefficients at those epochs.