Ionospheric effects of St. Patrick's storm over Asian Russia: 17–19 March 2015

• Published in: Journal of geophysical research. Space physics 2017-02, Vol.122 (2), p.2484-2504
• Main Authors: Zolotukhina, N., Polekh, N., Kurkin, V., Rogov, D., Romanova, E., Chelpanov, M.
• Format: Article
• Language: English
• Subjects: Atmospheric models; Coherent radar; Computer simulation; Convection modes; Empirical analysis; F 2 region; Field of view; Geomagnetic latitude; Geomagnetism; Geophysical data; Geophysics; Interplanetary magnetic field; Ionization; Ionosphere; ionospheric and ground backscatterskscatters; ionospheric and magnetic disturbances; Ionospheric disturbances; Ionospherics; Latitude; Magnetic fields; Magnetic storms; Magnetosphere; Magnetospheres; Particle physics; Phases; Precipitation; Radar; riometric absorption; severe geomagnetic storm; Solar wind; Storms; Thermosphere; total electron content; Yekaterinburg radar
• ISSN: 2169-9380; 2169-9402
• DOI: 10.1002/2016JA023180

We have carried out a comprehensive analysis of data from the high‐frequency coherent radar located near Yekaterinburg, ground‐based ionospheric, riometric, and magnetic stations, situated within the radar field of view and in the vicinity of it, as well as from eight radio paths crossing the Asian region of Russia. Using these data, we studied dynamics of ionospheric disturbances over wide longitudinal sector during the first 3 days of the St. Patrick's two‐step severe geomagnetic storm and determined the main mechanisms of their development. We showed that on 17 March during the main and early recovery storm phases, the major contribution to the generation of the ionospheric disturbances had been made by impact ionization by precipitating magnetospheric particles. This had lead to appearance of intense sporadic layers, alternating with intervals of total absorption. The main features of the storm were the large latitude width of the auroral precipitation zone and an expansion of this zone to corrected geomagnetic latitude ~ 45°. We suppose that these peculiarities were due to high variability of interplanetary magnetic field and solar wind impacted on the magnetosphere. The most probable cause of the negative ionospheric disturbance on 18 March might have been a change in the neutral atmosphere composition. Significant differences between measured and simulated values of maximal electron concentration in F2 layer point to the need to improve the existing empirical models of thermosphere, auroral precipitations, and magnetospheric convection in order to use them for modeling of ionospheric parameters during severe geomagnetic storms. Key Points Strong variability of solar wind and interplanetary magnetic field caused an extensive region of severely disturbed ionosphere Impact ionization was the main cause of the midlatitude ionosphere disturbances during the main storm phase An equatorward spreading of disturbed ionosphere are clearly seen in radar and oblicue‐incident sounding data