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Ann. Geophys., 23, 3139-3147, 2005
www.ann-geophys.net/23/3139/2005/
© European Geosciences Union 2005
The east-west asymmetry in Coronal Mass Ejections: evidence for active longitudes
M. Skirgiello
Space Research Center of Polish Academy of Sciences, Warsaw, Poland
Abstract. Various manifestations of solar activity are not uniformly distributed with
heliographic longitude. By using east-west asymmetry in the occurrence rate of
CMEs (coronal mass ejections), the longitudinal dependence in SOHO LASCO
1996-2004 data has been studied in this work. The solar rotation periodicity
has been found, indicating the presence of active longitudes, whose phase is
reversed twice during the studied period. It is more prominent in the
Southern Hemisphere. The east-west asymmetry is also present when calculated
for longer time periods. Sometimes (particularly during low solar activity),
there is an alternation of the eastern and western domination every six months.
Taking into account the orbital revolution of the Earth about the Sun, this
indicates the existence of enhanced activity, fixed in space (not undergoing
Carrington rotation). Moreover, there is about a 3.7% overall excess of
western events, lasting for the entire reported time, suggesting some bias in
the observations. A hypothesis to explain this phenomenon is proposed.
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