Fig. 8

Gain-corrected image of a bifurcation anomaly from Swarm A from 13 March 2015. Left panel: bifurcation of nominal ion peak associated with apparently larger kinetic energy (shift of peak to the left) than normal. Right panel: gain-corrected image obtained \({\sim }46\) min later showing no evidence of bifurcation in the same region of the detector, ruling out gain depletion or other detector anomaly as the root cause of the bifurcation