• Journal of Astronomy and Space Sciences
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• v.25 no.2
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• pp.139-148
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• 2008

It has been known that high-speed solar wind streams associated with coronal holes lead to quasi-periodic substorms that occur approximately every $2{\sim}4$ hours. In this paper we examined 222 repetitive substorms that occurred during high-speed stream periods in July through December in 2003 to quantitatively determine a range of energy input from the solar wind into the magnetosphere between two consecutive substorms. For this study, we have used the Akasofu ${\varepsilon}$-parameter to time-integrate it for the interval between two consecutive substorms, and have applied this method to the 222 substorms. We find that the average amount of solar wind input energy between two adjacent substorms is $1.28{\times}10^{14}J$ and about 85% out of the 222 substorms occur after an energy input of $2{\times}10^{13}{\sim}2.3{\times}10^{14}J$. Based on these results, we suggest that it is not practical to predict when a sub storm will occur after a previous one occurs purely based on the solar wind-magnetosphere energy coupling. We provide discussion on several possible factors that may affect determining substorm onset times during high-speed streams.

• Journal of Astronomy and Space Sciences
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• v.26 no.4
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• pp.439-450
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• 2009

Recurrent enhancements of relativistic electron events at geosynchronous orbit (GREEs) were observed in 2006. These GREE enhancements were associated with high-speed solar wind streams coming from the same coronal hole. For the first six months of 2006, the occurrence of GREEs has 27 day periodicity and the GREEs were enhanced with various flux levels. Several factors have been studied to be related to GREEs: (1) High speed stream, (2) Pc5 ULF wave activity, (3) Southward IMF Bz, (4) substorm occurrence, (5) Whistler mode chorus wave, and (6) Dynamic pressure. In this paper, we have examined the effectiveness about those parameters in selected periods.