Top: EISCAT Tromsø UHF radar Total Electron Content TEC and OMNI merging electric field centered 60-min moving averages in the time period of 2–6 February 2019 from 18 UT to 6 UT. The dash-dotted light pink line corresponds to the 90–500 km TEC, the dotted dark blue line corresponds to the 150–500 km TEC, and the violet dashed line corresponds to the 90–150 km TEC. The black solid line represents OMNI E _m . Bottom: Scatter plot of 60-min moving averages, and 1-hour resampled E _m and TEC, respectively, for E, F, combined regions of the ionosphere from 18 UT to 6 UT. The confidence interval of 0.95 is shown by the red shaded area surrounding the red line.