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Principal Component Analysis of Geomagnetic Activity: New Information on Solar Wind

Published online by Cambridge University Press:  24 July 2018

Kalevi Mursula Open the ORCID record for Kalevi Mursula [Opens in a new window]  and
Lauri Holappa
Kalevi Mursula
Affiliation:
ReSoLVE Centre of Excellence, Space Climate Research Unit, University of Oulu, Finland email: [email protected]
Lauri Holappa
Affiliation:
ReSoLVE Centre of Excellence, Space Climate Research Unit, University of Oulu, Finland email: [email protected]
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Abstract

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We use the principal component analysis to study geomagnetic activity at annual resolution using a network of 26 magnetic stations in 1966-2015, and an extended network of 40 stations in 1980-2015. The first principal component describes the long-term evolution of global geomagnetic activity, and has an excellent correlation with indices like the Kp/Ap index. The two networks give identical results for the first principal component. The second principal component is highly correlated with the annual percentage of high-speed streams (HSS). The extended network has a slightly higher sensitivity to HSSs. We verify the non-trivial latitudinal distribution of the second empirical orthogonal function. We find that the amplitude of the 22-year variation of geomagnetic activity has a closely similar latitudinal distribution as the second empirical orthogonal function. This verifies that the 22-year variation of geomagnetic activity is related to HSSs. The most likely cause is the Russell-McPherron mechanism.

Keywords

Space climateGeomagnetic activityHigh-speed solar windPrincipal component analysis
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 13 , Symposium S335: Space Weather of the Heliosphere: Processes and Forecasts , July 2017 , pp. 197 - 200
Copyright
Copyright © International Astronomical Union 2018 

References

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Mursula, K. & Martini, D., 2007, Geophys. Res. Lett., 34, L22, 107Google Scholar
Russell, C. T. & McPherron, R. L., 1973, J. Geophys. Res., 78, 92Google Scholar