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A Fortran computer programme for spherical harmonic analysis of geomagnetic field by numerical integration

  • G. K. Rangarajan
  • D. R. K. Rao
Article
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Abstract

A computer program in Fortran IV language for evaluating the spherical harmonic coefficients from grid values of the field componentsX, Y andZ over the surface of a sphere and for separating the harmonic coefficients into ‘internal’ and ‘external’ part is detailed. The method of “Numerical integration” using orthogonality relations of the associated Legendre functions is adopted wherein arbitrary relative weights for observations generally used in the method of “least squares” is eliminated and the derived coefficients are independent of the number of terms retained in the series. The computer program is tested for correctness using the charted values of the field components for two epochs 1945·0 and 1965·0.

Keywords

Field Component Legendre Function Fortran Computer Programme Orthogonality Relation Harmonic Coefficient 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    Vestine, E. H., Laporte, L., Lange, I. and Scott, W. E.,The Geomagnetic Field, its Description and Analysis. Carnegie Institution of Washington, Publ. No. 80, 3 (1947).Google Scholar
  2. 2.
    Jones, H. S. and Melotte, P. J.,Mon. Not. R. Astr. Soc. (Geophys. Suppl.) 6 409 (1953).Google Scholar
  3. 3.
    Chakrabarty, S. K.,Indian J Met. Geophys. (Spl. No.), 63 (1954).Google Scholar
  4. 4.
    Chapman, S. and Bartels, J.,Geomagnetism. Vol. II, Clarendon Press, Oxford (1940).Google Scholar
  5. 5.
    Kahle, A. B., Kern, J. W. and Vestine, E. H.,J. Geomagn. Geoelect. 16 229 (1964).Google Scholar
  6. 6.
    Kahle, A. B., Kern, J. W. and Vestine, E. H.,Memorandum RM-47O-NASA (1965).Google Scholar

Copyright information

© Indian Academy of Sciences 1975

Authors and Affiliations

  • G. K. Rangarajan
    • 1
  • D. R. K. Rao
    • 1
  1. 1.Indian Institute of GeomagnetismBombay

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