Figure 1: Average Poynting flux observed by Swarm A satellite crossings of the northern and southern auroral zones. Dayside (left column) and nightside (right column) auroral zone crossings for northern near-summer solstice (1-31 July, 2016; top row, panels (a) and (b)) and northern near-winter solstice (15 November-15 December, 2016; bottom row, panels (c) and (d)), during periods where the orbits are confined to the noon-midnight local time sector (see also Supplementary Figure 5). The panels compare Poynting flux as a function of transverse spatial scale, derived using a time-domain Savitzky-Golay filter, in the northern and southern hemispheres (blue and red, respectively) and plot the median Poynting flux power values (solid line) and the 25% and 75% quartiles (error bars). Three regions separating small-scale (10-150 km), mesoscale (150-250 km) and large-scale (>250 km) phenomena as observed along the Swarm orbit, as per the definitions in [21] are denoted by pink, green, and blue backgrounds, respectively.