Geoeffectiveness of solar events during the solar cycles 23 and 24

Résumé

In this study, we analyzed the geoeffectiveness of quiet and shocks solar events during the solar cycles 23
and 24. It appears that solar cycle 24 is magnetically quiet compared to solar cycle 23. Shock events are
more geoeffective during the solar cycle 23 compared to the solar cycle 24. A statistical analysis of solar
events shows that the different types of shocks do not have the same occurrences. During the solar cycle
23, 20%, 68% and 64% of the shocks of one day, two and three days respectively have been geoeffective.
However during the solar cycle 24, 18%, 28% and 47% of one-day, two-day, and three-day shocks
respectively have been geoeffective. This low geoeffectiveness of the shocks observed during solar cycle
24 is due to the weak solar winds recorded during this period. One-day shocks appear to be less
geoeffective compared to two-day and three-day shocks due to the important rate of speed below 550
km/s.