Irkutsk, Russian Federation
Irkutsk, Russian Federation
Irkutsk, Russian Federation
We have estimated seasonal variations in the main thermospheric gas components [O]/[N₂] and [O₂]/[O] for the period 2014–2017. We have used the well-known authoring technique and electron density measurements made with the Irkutsk digisonde (52° N, 104° E) at ionospheric F1-layer heights under different geomagnetic activity conditions. We have found that at these heights during geomagnetic disturbances in all seasons the molecular component of the neutral composition of the thermosphere increases and the atomic component decreases. In comparison with 2014, [O₂]/[O] values increased by 2017 under quiet and disturbed geomagnetic conditions: up to 30 % and 20 % in summer and spring respectively; up to 10 % in winter and autumn. The [O]/[N₂] ratio decreased by an average of 15 % by 2017. The assumption has been confirmed that in summer under quiet geomagnetic conditions the relative molecular oxygen content [O₂]/[O] increases with decreasing solar activity.
geomagnetic disturbances, gas component ratios
1. Goncharenko L., Salah J., Crowley G., Paxton L.J., Zhang Y., Coster A., Rideout W., Huang C., Zhang S., Reinisch B., Taran V. Large variations in the thermosphere and ionosphere during minor geomagnetic disturbances in April 2002 and their association with IMF By. J. Geophys. Res. 2006, vol. 111, A03303. DOI:https://doi.org/10.1029/2004JA010683.
2. Hedin A.E. MSIS-86 thermospheric model. J. Geophys. Res. 1987, vol. 92, no. A5, pp. 4649-4662.
3. Kushnarenko G.P., Kuznetsova G.M., Kolpakova O.E. The estimations of the ratios of the major gas constituents during strong and moderate geomagnetic disturbances in the descending phase of solar activity and solar minimum. Solnechno-zemnaya fizika [Solar-Terrestrial Physics]. 2011, vol. 19, pp. 134-139. (In Russian).
4. Kushnarenko G.P., Kuznetsova G.M., Yakovleva O.E. Seasonal changes of the thermospheric main gas components ratios during the last solar activity minimum (2007-2009). Solnechno-zemnaya fizika [Solar-Terrestrial Physics]. 2014, vol. 25, pp. 29-32. (In Russian).
5. Kushnarenko G.P., Yakovleva O.E., Kuznetsova G.M. Long-term variations in neutral gas composition of the thermosphere above Irkutsk. Solnechno-zemnaya fizika [Solar-Terrestrial Physics]. 2015, vol. 1, no. 4, pp. 30-34. DOI:https://doi.org/10.12737/13457. (In Russian).
6. Lastovicka J. Monitoring and forecasting of ionospheric space weather-effects of geomagnetic storms. J. Atmos. Solar-Terr. Phys. 2002, vol. 64, rp. 697-705.
7. Picone J.M., Hedin A.E., Drob D.P., Aikin A.C. (GTD7-2000) NRLMSISE-00 Empirical model of the atmosphere: statistical comparisons and scientific issues. J. Geophys. Res. 2002, vol. 107, no. A12, p. 1469. DOI:https://doi.org/10.1029/2002JA009430.
8. Tobiska W.K., Eparvier F.G. EUV97: Improvements to EUV irradiance modeling in the soft X-rays and EUV. Solar Phys. 1998, vol. 147, no. 1, pp. 147-159.
9. Shchepkin L.A., Kushnarenko G.P., Kuznetsova G.M., Freizon I.A. The middle ionosphere parameters dependence upon the solar and geomagnetic activities. 1. The development degree of the F1 layer. Geomagnetizm i aeronomiya [Geomagnetism and Aeronomy]. 1998, vol. 38, no. 5, pp. 72-76. (In Russian).
10. Shchepkin L.A., Kushnarenko G.P., Kuznetsova G.M. The possibility of estimations of the atomic and molecular oxygen relative abundance according to electron density measurements in the middle ionosphere. Geomagnetizm i aeronomiya [Geomagnetism and Aeronomy]. 2008, vol. 48, no. 1, pp. 129-133. (In Russian).
11. Shchepkin L.A., Kuznetsova G.M., Kushnarenko G.P. The estimations of atomic and molecular oxygen the relative abundance at height of 120 km according to the ionospheric measurements. Geomagnetizm i aeronomiya [Geomagnetism and Aeronomy]. 2009, vol. 49, no. 4, pp. 350-353. (In Russian).
12. URL: http://ckp-rf.ru/ckp/3056 (accessed January 31, 2020).
13. URL: http://wdc.kugi.kyoto-u.ac.jp (accessed January 31, 2020).
