Fig. 6From: A minimum in the latitude variation of spread-F at March equinoxLatitude variations of a percentage of days of spread-F occurrence, b mean onset time of spread-F, and c mean duration of spread-F in 2002 (black), 2003 (blue) and 2006 (red). The onset time and duration of the lone case at 36.5° N (Wakkanai) in 2002 are not plottedBack to article page