Connection of total electron content disturbances with AE index of geomagnetic activity during geomagnetic storm in March 2015

Abstract

Ionospheric response to the March 17, 2015 geomagnetic storm has been investigated using simulations of the Global Self-consistent Model of the Thermosphere, Ionosphere, Protonosphere (GSM TIP) [Dmitriev et al., 2017; Klimenko et al., 2018]. GSM TIP demonstrates results that do not contradict experimental data. This paper deals with GSM TIP simulated disturbances in the Total Electron Content (TEC) at different longitudes and zonal averages on March 17–23, 2015. At all longitudes, we can observe the existence of a band of TEC positive disturbances, located over the geomagnetic equator, and the formation of an after-storm ionospheric effect that appeared as positive TEC disturbances at midlatitude 3–5 days after the geomagnetic storm main phase. We have analyzed the dependence of disturbances of the thermosphere-ionosphere system (total electron content, n(N2), n(O), zonal electric field, meridional component of the thermospheric wind at a height of 300 km, and electron temperature at a height of 1000 km), calculated by GSM TIP from variations in the geomagnetic activity index AE. The analysis is based on Pearson’s correlation coefficients, presented as maps of the dependence of the correlation coefficient on UT and latitude for selected longitudes and for zonal averaged values. The results suggest that at high latitudes of the Northern and Southern hemispheres the correlation coefficient of TEC disturbances and AE variations is close to 1 at all longitudes in the period from 12 UT to 23 UT. From 9 UT to 12 UT, the minimum value of the correlation coefficient is observed at all latitudes and longitudes. The time intervals of the correlation values are associated with the features of a particular geomagnetic storm, for which, for example, the interval from 12 UT to 23 UT on March 17, 2015 corresponds to the geomagnetic storm main phase. We discuss possible mechanisms for the formation of such a relationship between simulated TEC disturbances and the AE index.