Abstract
This article considers sparse available data on variations in the main parameters of the ionospheric F2 layer foF2(ss + 2) and hmF2(ss + 2) at the end of the 1990s and the beginning of 2000s. It is shown that the monotonous behavior of hmF2(ss + 2) obtained in earlier publications for the period after 1980 is violated. The hmF2(ss + 2) behavior obtains a more complicated nature by time with a tendency towards a decrease in hmF2(ss + 2) at the beginning of a new century. A statistically significant relationship between foF2(ss + 2) and hmF2(ss + 2) is discovered confirming the Rishbeth statement that during the first hours after sunset, the critical frequency foF2 is governed by dynamical processes via changes in the F2-layer height. It is found that at the end of the interval in question, there is a tendency towards deviations from the above-mentioned dependence. The latter could be a manifestation of the fact that changes in the aeronomical parameters caused by the general cooling and contraction of the thermosphere begin influencing the foF2 value. It is found that in the summer months, the foF2(ss + 2) value demonstrated a systematic decline tendency from the “boundary date” towards the beginning of the 2000s.
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References
Bremer, J., Trends over the Ionospheric E and F Regions over Europe, Ann. Geophys., 1998, vol. 16, pp. 986–996.
Danilov, A.D., Trends of Parameters of the Ionospheric F2 Layer as an Indicator of Trends in Thermospheric Winds, in Aeronomy of the Earth’s Atmosphere and Ionosphere, IAGA Springer Book, 2010 (accepted).
Danilov, A.D. and Vanina-Dart, L.B., Behavior of FoF2 and HmF2 after Sunset, Geomagn. Aeron., 2010, vol. 50, no. 6. pp. 825–832 [Geomagn. Aeron. (Engl. Transl.), 2010, vol. 50, p. 796–803].
Danilov, A.D. and Vanina-Dart, L.B., Parameters of the Ionospheric F2 Layer as a Source of Information on Trends in Thermospheric Dynamics, Geomagn. Aeron., 2010a, vol. 50, no. 2, pp. 195–208 [Geomagn. Aeron. (Engl. Transl.), 2010a, vol. 50, pp. 187–200].
Laštovička, J., Long-Term Trends in the Upper Atmosphere: Recent Progress, in Aeronomy of the Earth’s Atmosphere and Ionosphere, IAGA Springer Book, 2010 (accepted).
Laštovička, J., et al., Long-Term Trends in FoF2: A Comparison of Various Methods, J. Atmos. Sol.-Terr. Phys., 2006, vol. 68, pp. 1854–1870.
Laštovička, J., Akmaev, R.A., Beig, G., et al., Emerging Pattern of Global Change in the Upper Atmosphere and Ionosphere, Ann. Geophys., 2008, vol. 26, no. 5, pp. 1255–1268.
Marin, D., Mikhailov, A.V., de la Morena, B.A., and Herraiz, M., Long-Term HmF2 Trends in the Eurasian Longitudinal Sector on the Ground-Based Ionospheric Observations, Ann. Geophys., 2001, vol. 19, pp. 761–772.
Mikhailov, A.V., Ionospheric Long-Term Trends: If the Geomagnetic Control and the Greenhouse Hypotheses Can Be Reconciled., Ann. Geophys., 2006, vol. 24, pp. 2533–2541.
Mikhailov, A.V. and Perrone, L., On the Mechanism of Seasonal/Solar Cycle NmF2 Variations: A Quantitative Estimate of the Main Parameters Contribution Using ISR Observations, J. Geophys. Res., 2011 (submitted).
Rishbeth, H., How the Thermospheric Circulation Affects the Ionospheric F2 Layer, J. Atmos. Sol.-Terr. Phys., 1998, vol. 60, pp. 1385–1402.
Shimazaki, T., World Wide Daily Variations in the Height of the Maximum Electron Density in the Ionospheric F2 Layer, J. Radio Res. Labs. (Japan), 1995, vol. 2, pp. 85–97.
Ulich, T. and Turunen, E., Evidence for Long-Term Cooling of the Upper Atmosphere in Ionospheric Data, Geophys. Res. Lett., 1997, vol. 24, no. 9, pp. 1103–1106.
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Original Russian Text © A.D. Danilov, 2011, published in Geomagnetizm i Aeronomiya, 2011, Vol. 51, No. 3, pp. 325–332.
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Danilov, A.D. Variations in foF2 and hmF2 at the end of the 1990s and the beginning of the 2000s. Geomagn. Aeron. 51, 321–328 (2011). https://doi.org/10.1134/S0016793211030054
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DOI: https://doi.org/10.1134/S0016793211030054