Fig. 6
From: Occurrence of F region echoes for the polar cap SuperDARN radars
Line plots of the echo occurrence rate in percent (median values over 15-min intervals in 2014 smoothed by applying a running 1-h boxcar filter) versus time of a day for each season in the Northern (NH, left panels) and Southern (SH, right panels) hemispheres. The right and left panels are data over the same periods, e.g., panel a for the spring in the NH covers the same period as panel b for the fall in the SH