Fig. 7
From: Determining polar ionospheric electrojet currents from Swarm satellite constellation magnetic data
Correlation between AE index and the total polar current, I, as a function of period. The correlation is found for the period of 400 orbits from 7 March to 1 April 2015. The black curve shows the coherence of the AE index with the Northern Hemisphere, the red shows the coherence of the AE index with the Southern Hemisphere, and the blue curve shows the coherence of the Northern and Southern Hemisphere time series as a function of the period of the signal