Main ionospheric trough and field-aligned currents responses to the geomagnetic storms in October 2015 and September 2017

The Earth's ionosphere is a coupled system affected by interactions with precipitating energetic particles and electrical currents from the Earth's magnetosphere, and in addition by upward propagating disturbances from lower atmospheric layers. Geomagnetic disturbances triggered by solar activity influence the ionosphere, its fine and global structures. The energy injection into the magnetosphere during geomagnetic storms and substorms directly affects the auroral and sub-auroral region of the Earth’s ionosphere, where auroral oval expansion and variations of plasma density and field-aligned currents intensity can be observed. Main ionospheric trough (MIT) and field-aligned currents (FACs) are very sensitive to geomagnetic conditions. This work analyses both phenomenon response to the elevated geomagnetic conditions during October 2015 and September 2017 geomagnetic storms. The analysis is based on the data from the Swarm and DMSP missions.