Fig. 7

a–d Smoothed average values of the echo occurrence rate for the Clyde River (CLY) and Inuvik (INV) radars as a function of the F region peak electron density (inferred from concurrent and co-located Rankin Inlet (RKN) elevation angle measurements). All noon sector data collected in 2013–2017 were considered. Individual curves in each panel correspond to three bins of the E × B plasma flow magnitude of 50–250 m/s, 250–400 m/s, and > 400 m/s. Also presented in each panel is the total number of 15-min intervals available to build each curve. e–h Smoothed average values of the echo occurrence rate for the CLY and INV radars versus the E × B plasma flow magnitude. Individual curves in each panel correspond to four bins of the F region peak electron density of \( < 2 \times 10^{11} \,{\text{m}}^{ - 3} \), \( (2 - 3) \times 10^{11} \,{\text{m}}^{ - 3} \), \( (3 - 4) \times 10^{11} \,{\text{m}}^{ - 3} \), and \( > 4 \times 10^{11} \,{\text{m}}^{ - 3} \). The linear fit lines are shown for each set of points