Fig. 2
From: Two current systems in the preliminary phase of sudden commencements in the magnetosphere
(Top row) Temporal evolution of the FAC distribution in the northern hemisphere at latitudes above 60° from t = 5.2 to 5.9 min. The black arrows at t = 5.5 and 5.9 min indicate the FACs of the PI. The red thick lines labeled AH and AL in the 5.5-min panel and BH, Bc, and BL in the 5.9-min panel indicate the footpoints of the current systems shown in Figs. 3 and 4. The latitude and MLT of these footpoints are as follows: AH = (75.5°, 12.6–13.1 MLT); AL = (69.1°, 14.0–14.8 MLT); BH = (73.6°, 12.6–13.1 MLT); BC = (71.3°, 13.8–15.0 MLT); BL = (65.9°, 16.2–16.8 MLT). (Bottom row) Temporal evolution of the electric potential distribution for the same region and time intervals