Fig. 2.

Variation of the monthly median values of Hm in km, at Ebro, for the four seasons (winter, spring, summer and fall) and for the high solar-activity years (a) 2000, (b) 2001, and for the low solar-activity years (c) 2006 and (d) 2007.
Variation of the monthly median values of Hm in km, at Ebro, for the four seasons (winter, spring, summer and fall) and for the high solar-activity years (a) 2000, (b) 2001, and for the low solar-activity years (c) 2006 and (d) 2007.