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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 22, issue 1
Ann. Geophys., 22, 25–33, 2004
https://doi.org/10.5194/angeo-22-25-2004
© Author(s) 2004. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 22, 25–33, 2004
https://doi.org/10.5194/angeo-22-25-2004
© Author(s) 2004. This work is distributed under
the Creative Commons Attribution 3.0 License.

  01 Jan 2004

01 Jan 2004

Climatology of ionospheric slab thickness

B. Jayachandran1, T. N. Krishnankutty2, and T. L. Gulyaeva3,4 B. Jayachandran et al.
  • 1Sree Narayana College, Varkala, Trivandrum, Kerala, 695145, India
  • 2Sree Narayana College, Kollam, Kerala, 691001, India
  • 3IZMIRAN, 142190 Troitsk, Moscow Region, Russia
  • 4Space Research Centre, PAS, Bartycka, 18A, Warsaw, Poland

Abstract. The ionospheric slab thickness τ defined as a ratio of the total electron content (TEC) to the F-region peak electron density (NmF2) has been analysed during the solar maximum (1981) and minimum (1985) phases of an intense, the 21st, solar cycle. Hourly values of TEC and NmF2 collected at Hawaii (low-latitude), Boulder (mid-latitude) and Goosebay (high-latitude) are used in the study. Climatology of the slab thickness is described by the diurnal, seasonal, solar and magnetic activity variations of τ for the different latitude zones. It is found that, for magnetically quiet days of solar maximum, increased ionization of NmF2 and TEC during the daytime is accompanied by an increased thickness of the ionosphere compared to the night-time for non-auroral latitudes. However, the reverse is found to be true during the solar minimum compensating TEC against a weak night-time ionization of NmF2. For the high-latitude the night-time slab thickness is higher compared to the daytime for both the solar phases. Ratios of daily peak to minimum values of slab thickness vary from 1.3 to 3.75 with the peaks of τ often observed at pre-sunrise and post-sunset hours. The average night-to-day ratios of τ vary from 0.68 to 2.23. The day-to-day variability of τ, expressed in percentage standard deviation, varies from 10% by day (equinox, high-latitude) to 67% by night (summer, mid-latitude) during solar minimum and from 10% by day (winter and equinox, mid-latitude) to 56% by night (equinox, high-latitude) during solar maximum. A comprehensive review of slab thickness related literature is given in the paper.

Key words. Ionospheric physics

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