Relationship between geomagnetic classes’ activity phases and their occurrence during the sunspot cycle

Frédéric Ouattara


Four well known geomagnetic classes of activity such as quiet days activity, fluctuating activity, recurrent activity
and shock activity time occurrences have been determined not only by using time profile of sunspot number
Rz but also by using aa index values.
We show that recurrent wind stream activity and fluctuating activity occur in opposite phase and slow solar wind
activity during minimum phase and shock activity at the maximum phase.
It emerges from this study that fluctuating activity precedes the sunspot cycle by π/2 and the latter also precedes
recurrent activity by π/2. Thus in the majority the activities do not happen at random; the sunspot cycle starts
with quiet days activity, continues with fluctuating activity and during its maximum phase arrives shock activity.
The descending phase is characterized by the manifestation of recurrent wind stream activity.


Classes of geomagnetic activity – Phases of geomagnetic classes – Sunspot cycle

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Published by INGV, Istituto Nazionale di Geofisica e Vulcanologia - ISSN: 2037-416X