Studying Peculiarities of Ionospheric Response to the 2015 March 17-19 Geomagnetic Storm in East Asia: Observations and Simulation
Abstract
We report results of the research into effects of the strong geomagnetic storm in the ionosphere of high, middle, and low latitudes on March 17-19, 2015. The research relies on measurements made at the network of ionospheric stations located near the 120°E meridian. The analysis of experimental data has revealed that at the beginning of the main storm phase the equatorial wall of the main ionospheric trough (MIT) shifted towards geographic latitudes 58-60°N, which caused negative disturbances in subauroral latitudes and positive disturbances in middle latitudes. Further displacement of the MIT equatorial wall towards a geographic latitude of 52° N led to a decrease in the F2-layer critical frequency (foF2) up to 2 MHz in middle latitudes during evening and night hours, and to the appearance of sporadic layers in these latitudes due to energetic particle precipitation. Such phenomena are largely specific to the subauroral ionosphere. During the recovery storm phase on March 18, 2015 during daylight hours, negative disturbances were recorded at all the stations. Since prolonged negative disturbances are usually associated with a reduction in the ratio of concentrations of atomic oxygen and molecular nitrogen [O]/[N2] which is transported by disturbed thermospheric wind from auroral latitudes to middle and low ones, we analyzed measurements of [O]/[N2], made by GUVI (Global Ultraviolet Imager, http://guvi.jhuapl.edu/site/gallery/guvi-galleryl3on2.shtml), during this storm. The storm appeared to be characterized by very low values of [O]/[N2] which were recorded in the longitude sector 60 - 150°E up to 15°N on March 18. The discovered peculiarities of the ionospheric response to the storm were interpreted using a theoretical model of ionosphere-plasmosphere coupling developed at ISTP SB RAS. The simulation showed that the displacement of MIT equatorial wall resulted in foF2 variations similar to those observed during the main storm phase in subauroral and middle latitudes. The prolonged negative disturbances during the recovery storm phase in middle latitudes are attributed to variations in the global wind circulation and to [O]/[N2] reduction; in low latitudes, a prolonged negative disturbance is also conditioned by variations in the global wind circulation and, to a lesser extent, by [O]/[N2] reduction as well as by penetration of electric fields to low latitudes; hence there was no equatorial anomaly on March 18. This is confirmed by total electron content data (http://cdaweb.gsfc.nasa.gov/cgi-bin/eval2.cgi). The recovery storm phase lasted until mid-March 25. The work is supported by the Russian Foundation for Basic Research (RFBR grant No. 16-55-53003_DVEH_a).
- Publication:
-
41st COSPAR Scientific Assembly
- Pub Date:
- July 2016
- Bibcode:
- 2016cosp...41E1652R