Figure 3
From: Ionospheric current contribution to the main impulse of a negative sudden impulse
Transient variation of the H component in various local time sectors. (a-h) H field in various longitudinal sectors at different latitudes (indicated on the right), background curves shown by thin lines represent the average of three quiet days. The vertical line at 11:50 UT shows the onset time of the negative impulse (for details see text).