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Volume 61 Supplement 5

Special Issue: Flare-Substorm/Space Weather Topics

Proxy for the ionospheric peak plasma density reduced by the solar zenith angle


The F2 layer peak plasma density NmF2 is reduced by the factor constructed from the relative changes in the Sun’s zenith angle ξ for a particular local time and the local noon value χ0. Proposed transformation yields a proxy for the peak plasma density which coincides with the source observation at noon but apart from the latter is gradually reduced towards the night. Hourly observations at 8 ground based ionosondes for the solar maximum (2000) and minimum (2006) are analyzed for inter-stations and inter-seasonal correlation of the peak plasma density and the proxy values. The proxy values show improved correlation between the data at different locations and improved inter-seasonal correlations for a particular location due to greater homogeneity of results throughout the year contributing to improved evaluation of the ionospheric weather indices.


  • Besprozvannaja, A. S., On a nature of the seasonal anomaly of the F2 layer noon ionization, Geomagn. Aeronomy, 10, 986–992, 1970.

    Google Scholar 

  • Besprozvannaja, A. S., Peculiarities of the regular F2 layers, Geomagn. Aeronomy, 27, 728–734, 1987.

    Google Scholar 

  • Bilitza, D., International Reference Ionosphere 2000, Radio Sci., 36(2), 261–275, 2001.

    Article  Google Scholar 

  • Chapman, S., Absorption and dissociative or ionizing effect of monochromatic radiation in an atmosphere on a rotating earth, Proc. Phys. Soc., London, 43, 26–45, 1931.

    Article  Google Scholar 

  • Gulyaev, R. A. and T. L. Gulyaeva, On illuminating the ionosphere by sunlight during nighttime, Geomagn. Aeronomy, 24, 347–348, 1984.

    Google Scholar 

  • Gulyaeva, T. L., I. Stanislawska, and M. Tomasik, Ionospheric weather: Cloning missed foF2 observations for derivation of variability index, Ann. Geophys., 26, 315–321, 2008.

    Article  Google Scholar 

  • Lal, C., Contribution to F2 layer ionization due to the solar wind, J. Atmos. Solar-Terr. Phys., 59(17), 2203–2211, 1997.

    Article  Google Scholar 

  • McNamara, L., Private communication, 1986.

  • Mikhailov, A. V. and V. V. Mikhailov, A new ionospheric index MF2, Adv. Space Res., 15(2), 93–97, 1995.

    Article  Google Scholar 

  • Rotwell, P., Charged particles in the Earth’s magnetic field and the ionospheric F2-layer, J. Phys. Soc. Japan, 17, Suppl. 1, 263–267, 1962.

    Google Scholar 

  • Williscroft, L.-A. and A. W. V. Poole, Neural networks, foF2, sunspot number and magnetic activity, Geophys. Res. Lett., 23(24), 3659–3662, 1996.

    Article  Google Scholar 

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Correspondence to T. L. Gulyaeva.

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Gulyaeva, T.L. Proxy for the ionospheric peak plasma density reduced by the solar zenith angle. Earth Planet Sp 61, 629–631 (2009).

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