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

Some statistics concerning the daily geomagnetic character figureCp


The frequency distribution ofCp over its range 0 to 2.5 has been determined and is discussed for groups of days selected according to (a) calendar month and (b) season (D, E, J)—1932–1965 inclusive—and for each of eleven year-groups selected in various ways on the basis of the annual mean sunspot number. For each group the median, mean and root-mean-square value ofCp has been found. The results favor the equinoctial hypothesis for the semi-annual variation of geomagnetic disturbance.

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


  1. [1]

    J. Bartels,Terrestrial magnetic activity and its relation to solar phenomena, Terr. Magn. Atmos. Elect.37 (1932), 1–52.

  2. [2]

    J. Bartels,Collection of Geomagnetic Planetary Indices Kp and Derived Daily Indices, Ap and Cp, for the Years 1932 to 1961, IAGA Bulletin No. 18 (North-Holland Publishing Co., Amsterdam 1962).

  3. [3]

    S. Chapman andJ. Bartels,Geomagnetism (Clarendon Press, Oxford/London 1962).

  4. [4]

    A. L. Cortie,Sunspots and terrestrial magnetic phenomena 1898–1911, Month. Not. Roy. Astron. Soc.73 (1912), 52–60.

  5. [5]

    D. H. McIntosh,On the annual variation of magnetic disturbance, Phil. Trans. Roy. Soc. London [A]251 (1959), 525–552.

  6. [6]

    W. Priester andD. Cattani,On the semiannual variation of geomagnetic activity and its relation to solar corpuscular radiation, J. Atmos. Sci.19 (1962), 121–126.

Download references

Author information

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Gupta, J.C., Chapman, S. Some statistics concerning the daily geomagnetic character figureCp . PAGEOPH 68, 103–112 (1967).

Download citation


  • Frequency Distribution
  • Sunspot Number
  • Geomagnetic Disturbance