Polar Synoptic Perturbation Maps
Each polar panel shows a six-hour span of data from either the northern or southern hemisphere plotted in magnetic coordinates. Points flagged as real signatures are plotted as blue (eastward) or red (westward) and the darker points indicate more intense perturbations. Data coverage is indicated by plotting satellite locations at the time of all magnetic data values by small gray dots which appear as dust. The distribution of satellite tracks in magnetic coordinates is apparent in the diurnal ‘wobble’ of the data coverage.
The green circle is a least squares fit to the perturbations that represent what is called the Region 1/Region 2 current system. In the northern hemisphere these perturbations are eastward in the dusk side (1200 to 2400 magnetic local time, MLT) and westward in the dawn side (0000 to 1200 MLT). The sense of these perturbations is reversed in the southern hemisphere. This circle represents an estimate of the average centroid of the auroral electrojet.
The yellow annulus shows the annulus that encompasses 60% of the perturbations. The poleward and equatorward boundaries are determined by ordering the points by distance from the center of the electrojet fit (green circle). The yellow annulus indicates the region that begins at the 20th percentile and extends to the 80th percentile and thus indicates the approximate latitudinal extent of the electrojet currents.