Dayside (a, c, e, g) and nightside (b, d, f, h) auroral zone crossings for northern near-summer solstice (1–31 July, 2016; a and b), northern spring period (20 March–20 April, 2017; c and d), northern equinox period (20 February–25 March, 2016; e and f) and northern near-winter solstice (15 November–15 December, 2016; g and h), during periods where the orbits are confined to the noon–midnight local time sector (see also Supplementary Fig. 9). 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 ref. 37 are denoted by pink, green and blue backgrounds, respectively.