Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Local time dependence of amplitude and phase of annual and semiannual components inH

  • 27 Accesses

  • 1 Citations


Using the monthly mean diurnal inequalities of Colaba horizontal force for each of the 24 local hours given by Moos, the amplitudes of the sine and cosine terms of the annual and semiannual components and their mean errors were obtained by the application of the least-squares method and solution of simultaneous equations. The annual-component amplitude is largest for 13 hours and the epoch of maximum for most of the sunlit hours is in May. The semiannual component attains large amplitude during the forenoon hours, while its epoch of maximum shows considerable variation. A discontinuity is observed around 18 hours in the trend of change in amplitude and phase of both components, suggesting the effect of partial ring currents.

This is a preview of subscription content, log in to check access.


  1. [1]

    N. A. F. Moos,Magnetic Observations made at the Government Observatory Bombay for the period 1846–1905 and their Discussion, Part II. The Phenomenon and its Discussion (1910).

  2. [2]

    B. N. Bhargava, Planet. Space Sci.20 (1972), 423.

  3. [3]

    D. E. Winch, Geophys. J. R. Astr. Soc.8 (1965), 258.

  4. [4]

    H. F. Petersons, Aust. J. Phys.23 (1970), 905.

  5. [5]

    B. N. Bhargava, Ann. Geophys.28 (1971), 357.

  6. [6]

    R. P. Kane, Ann. Geophys.27 (1971), 237.

  7. [7]

    J. A. Fejer, Canad. J. Phys.39 (1961), 1409.

  8. [8]

    W. D. Cummings, J. Geophys. Res.71 (1966), 4495.

  9. [9]

    B. N. Bhargava andA. Yacob, J. Geomag. Geoelect.23 (1971), 249.

Download references

Author information

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Yacob, A. Local time dependence of amplitude and phase of annual and semiannual components inH . PAGEOPH 111, 2319–2323 (1973). https://doi.org/10.1007/BF00940884

Download citation


  • Sine
  • Time Dependence
  • Local Time
  • Large Amplitude
  • Simultaneous Equation