Unusually high thermospheric hydrogen density prior to severe storm of September 8, 2017 and its impact on the storm manifestations
- 1Institute of Ionosphere, Ukraine (dmitrykotoff@gmail.com)
- 2University of Alabama in Huntsville, USA
- 3National Technical University ‘Kharkiv Polytechnic Institute’
- 4Cooperative Institute for Research in Environmental Sciences, University of Colorado, USA
- 5Space Weather Prediction Center, National Oceanic and Atmospheric Administration, USA
- 6Institute of Atmospheric Physics of the Czech Academy of Sciences, Czech Republic
- 7Eötvös Loránd University, Hungary
- 8Geodetic and Geophysical Institute, RCAES, Hungarian Academy of Sciences, Hungary
- 9UPC-IonSAT, IEEC-UPC, Universitat Politècnica de Catalunya, Spain
- 10Institute for Space-Earth Environmental Research, Nagoya University, Japan
- 11Graduate School of Natural Science and Technology, Kanazawa University, Japan
- 12Graduate School of Science, Tohoku University, Japan
- 13Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Japan
Atomic hydrogen plays a key role for the plasmasphere, exosphere, and the nighttime ionosphere. It directly impacts the rate of plasmasphere refilling after strong magnetic storms as atomic hydrogen is the primary source of hydrogen ions. It is the source of the geocorona, which significantly affects ring current decay during the recovery phase of magnetic storms.
Our previous studies with the Kharkiv incoherent scatter radar (49.6 N, 36.3 E), Arase and DMSP satellite missions, and FLIP physical model showed that during magnetically quiet periods of 2016–2018 the hydrogen density was generally a factor of 2 higher than from the NRLMSIS00-E model (Kotov et al., 2018).
Even larger values of thermospheric hydrogen density were detected prior to the severe storm of September 8, 2017. With Kharkiv IS radar, AWDANet whistler receivers, Arase satellite, and TEC data we found that during the nights of September 5 to 6 and September 6 to 7, the thermospheric hydrogen density had to be at least a factor of 4 higher than the values from NRLMSIS00-E model i.e. ~100% higher than expected from our previous studies. We discuss the possible mechanisms that could lead to the increased hydrogen density.
Such high hydrogen densities may be the reason for very quick recovery of inner plasmasphere after the severe depletion by the storm of September 8, 2017 (Obana et al., 2019).
References:
1. Kotov, D. V., Richards, P. G., Truhlík, V., Bogomaz, O. V., Shulha, M. O., Maruyama, N., et al. ( 2018). Coincident observations by the Kharkiv IS radar and ionosonde, DMSP and Arase (ERG) satellites, and FLIP model simulations: Implications for the NRLMSISE‐00 hydrogen density, plasmasphere, and ionosphere. Geophysical Research Letters, 45, 8062– 8071. https://doi.org/10.1029/2018GL079206
2. Obana, Y., Maruyama, N., Shinbori, A., Hashimoto, K. K., Fedrizzi, M., Nosé, M., et al. (2019). Response of the ionosphere‐plasmasphere coupling to the September 2017 storm: What erodes the plasmasphere so severely? Space Weather, 17, 861–876. https://doi.org/10.1029/2019SW002168
How to cite: Kotov, D., Richards, P., Bogomaz, O., Shulha, M., Maruyama, N., Fedrizzi, M., Truhlík, V., Lichtenberger, J., Hernández-Pajares, M., Miyoshi, Y., Kasahara, Y., Kumamoto, A., Tsuchiya, F., Shoji, M., Matsuoka, A., Shinohara, I., Zhivolup, T., Emelyanov, L., Chepurnyy, Y., and Domnin, I.: Unusually high thermospheric hydrogen density prior to severe storm of September 8, 2017 and its impact on the storm manifestations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6925, https://doi.org/10.5194/egusphere-egu2020-6925, 2020.
