pure and applied geophysics

, Volume 110, Issue 1, pp 2099–2107 | Cite as

Day-time variations of the equivalent electron concentration in the non-sounded lower ionosphere

  • K. B. Serafimov


Based on data on the lowest reflected frequencyfmin and on information on the lower and upper boundaries of the non-sounded lower ionosphere, an equivalent electron concentration for all concentrations below the correspondingfmin was determined. Day-time variations of the equivalent concentration are investigated, confirming that there is a cosine relation to the solar zenith angle. The power index of that relation has an outlined seasonal course with a maximum in April and October, while the absolute seasonal minimum is during the winter (the summer minimum is slightly outlined). The mean yearly values of the index are almost constant:n N ≈0.5 for solaractivity,I1500 to 115.10−22 W Hz−1 m2. During higher activityn N changes correspondingly toI1500 according to relation (12). The variations ofn N during high solar activity show that the altitude gradient and temperature gradient in the low ionosphere are becoming proportional toI1500 when the solar x-ray radiation exceeds a certain level. The results obtained confirm the reliability of the method developed for employingfmin in aeronomic investigations.


Radiation Temperature Gradient Solar Activity Electron Concentration Zenith Angle 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. [1]
    G. Nestorov andK. Serafimov, Geofis. pura appl.56 (3) (1963), 135.Google Scholar
  2. [2]
    K. Serafimov, Izv. Geofiz. institut na BAN,V (XIX) (1973).Google Scholar
  3. [3]
    K. Serafimov, Tech. Mitt. RFZ16 (4) (1972).Google Scholar
  4. [4]
    K. Serafimov,Physics of the Middle Ionosphere (Publishing House of the Bulg. Acad. of Sciences, Sofia 1970).Google Scholar
  5. [5]
    K. Serafimov, Compt. Rend. Acad. Bulg. Sci.24 (12) (1971), 1633.Google Scholar
  6. [6]
    Geophysikalische Meßreihen, OIF-Kühlungsborn.Google Scholar
  7. [7]
    G. Nestorov,Physics of the Lower Ionosphere (Publishing House of the Buig. Acad. of Sciences, Sofia 1969).Google Scholar
  8. [8]
    U. Hense, Tech. Mitt. RFZ14 (2) (1970), 73.Google Scholar

Copyright information

© Birkhäuser-Verlag 1973

Authors and Affiliations

  • K. B. Serafimov
    • 1
  1. 1.Group for Space Physics at the Bulgarian Academy of SciencesSofia

Personalised recommendations