Fig. 8.

Variation of the daily hourly values of Hm in km against time, at Ebro, for the four seasons of the high solar-activity year 2000: (a) winter, (b) spring, (c) summer, (d) fall and for the four seasons of the low solar-activity year 2007: (e) winter, (f) spring, (g) summer, (h) fall. The corresponding monthly median values and upper and lower quartiles are also plotted.