Fig. 8
From: Proton auroras during the transitional stage of substorm onset
Superposed epoch analysis of electron auroral and proton auroral variations. The time (x axis) used in this plot is normalized according to Eq. (1) in the text. a The variations of electron aurora arc inferred from THEMIS or MSP 557.7 nm observations in 12 substorm events. b The proton auroral variations inferred from FESO/MSP, in the same arc band as the electron aurora. Note in (a) and (b) a shaded region indicates that the sampled intensity may no longer represent preexisting arc after T1. c Total proton auroral intensities integrated over the FESO/MSP latitudes. In (d) and (e), we show the percentage variations of the arc band proton auroral intensity and the total proton auroral intensity, relative to their mean late growth phase values (see text for details). The scan time of FESO/MSP is marked by a horizontal bar. Different colors in this figure denote different events