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      https://www.ias.ac.in/article/fulltext/jess/092/01/0015-0030

    • Keywords

       

      Geomagnetic reference field; isomagnetic charts; secular variation; polynomial fit; analytical representation; spatial variation; temporal variation

    • Abstract

       

      The magnetic measurements of declination (D), horizontal (H) and vertical (Z) components of earth’s magnetic field, collected from ground surveys between 1962 and 1966, are used to develop an analytical model of geomagnetic field variations over Indian region for the epoch 1965. In order to reflect spatial features with wavelengths of approximately 1000 km, sixth degree polynomial as a function of differential latitude and longitude is calculated by the method of least squares. The root mean square fit of the model to the input data is better than that accounted by the International Geomagnetic Reference Field for 1965.0. Isomagnetic charts drawn forD, H, Z and total force (F) reflect more details than that shown on world magnetic charts. Further, the values of the field at common repeat stations recorded between 1962 and 1974, after eliminating the field values for the epoch 1965.0, are used to get the secular variation as well as its spatial dependence again by means of polynomial which now includes coefficients which are functions of time and of geographical locations. The accuracy of coefficients is tested against the behaviour of secular variation at permanent magnetic observatories. The merits and limitations of the model are discussed.

    • Author Affiliations

       

      B R Arora1 V H Badshah1 B P Singh1 M G Arur1 2 P S Bains1 2 Jeevan Lal1 2

      1. Indian Institute of Geomagnetism, Colaba, Bombay - 400 005, India
      2. Geodetic & Research Branch, Survey of India, Dehradun, India
    • Dates

       
  • Journal of Earth System Science | News

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