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Annales Geophysicae An open-access journal of the European Geosciences Union
Ann. Geophys., 35, 923-938, 2017
https://doi.org/10.5194/angeo-35-923-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Regular paper
09 Aug 2017
Similarity and differences in morphology and mechanisms of the foF2 and TEC disturbances during the geomagnetic storms on 26–30 September 2011
Maxim V. Klimenko1,2, Vladimir V. Klimenko1, Irina E. Zakharenkova1, Konstantin G. Ratovsky3, Nina A. Korenkova1, Yury V. Yasyukevich3, Anna A. Mylnikova3, and Iurii V. Cherniak4 1West Department of Pushkov IZMIRAN, RAS, Kaliningrad, Russia
2Immanuel Kant Baltic Federal University, Kaliningrad, Russia
3Institute of Solar-Terrestrial Physics, SB RAS, Irkutsk, Russia
4University of Warmia and Mazury, Olsztyn, Poland
Abstract. This study presents an analysis of the ground-based observations and model simulations of ionospheric electron density disturbances at three longitudinal sectors (eastern European, Siberian and American) during geomagnetic storms that occurred on 26–30 September 2011. We use the Global Self-consistent Model of the Thermosphere, Ionosphere and Protonosphere (GSM TIP) to reveal the main mechanisms influencing the storm-time behavior of the total electron content (TEC) and the ionospheric F2 peak critical frequency (foF2) during different phases of geomagnetic storms. During the storm's main phase the long-lasting positive disturbances in TEC and foF2 at sunlit mid-latitudes are mainly explained by the storm-time equatorward neutral wind. The effects of eastward electric field can only explain the positive ionospheric storm in the first few hours of the initial storm phase. During the main phase the ionosphere was more changeable than the plasmasphere. The positive disturbances in the electron content at the plasmaspheric heights (800–20 000 km) at high latitudes can appear simultaneously with the negative disturbances in TEC and foF2. The daytime positive disturbances in foF2 and TEC occurred at middle and low latitudes and at the Equator due to n(O) ∕ n(N2) enhancement during later stage of the main phase and during the recovery phase of the geomagnetic storm. The plasma tube diffusional depletion and negative disturbances in electron and neutral temperature were the main formation mechanisms of the simultaneous formation of the positive disturbances in foF2 and negative disturbances in TEC at low latitudes during the storm's recovery phase.

Citation: Klimenko, M. V., Klimenko, V. V., Zakharenkova, I. E., Ratovsky, K. G., Korenkova, N. A., Yasyukevich, Y. V., Mylnikova, A. A., and Cherniak, I. V.: Similarity and differences in morphology and mechanisms of the foF2 and TEC disturbances during the geomagnetic storms on 26–30 September 2011, Ann. Geophys., 35, 923-938, https://doi.org/10.5194/angeo-35-923-2017, 2017.
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Using model–data analysis we emphasize a new result – formation of the positive daytime disturbances in foF2 and TEC at middle and low latitudes due to n(O)/n(N2) enhancement during the recovery storm phase. The spatial extent of this phenomenon depends on the longitudinal sector. The positive disturbances in the electron content at heights of 800–20 000 km at high latitudes can appear simultaneously with the negative disturbances in TEC and foF2 due to electron and neutral temperature heating.
Using model–data analysis we emphasize a new result – formation of the positive daytime...
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