Local Time and Longitudinal Differences in the Occurrence Frequency of Ionospheric EMIC Waves During Magnetic Storm Periods

The spatial and temporal distributions of ionospheric electromagnetic ion cyclotron (EMIC) waves during magnetic storms from 2014 to 2018 were studied using Swarm observations. Ionospheric EMIC preferably occurred their recovery phases at subauroral regions within an average latitude 40–55°. There more wave events intense longer period storms. However, the correlation between event number storm duration was not good. This might be due effect heavy oxygen ions on generation loss ring current high-energy by waves. are obvious local time (MLT) differences in peak occurrence frequency phases. enhanced solar wind dynamic pressure favorable for duskside With increased substorm activity, rate shifted morning side dusk-premidnight sector. During phase a storm, 12–24 MLT sector appeared earlier part than those 00–12 shift is related eastward rotation plasmaspheric plume toward late its overlap with current. Highest could found South Atlantic Anomaly region, which drift shell splitting propagation weak field region.