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1 results

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

  • Kalevi Mursula, Lauri Holappa
  • Journal:
    Proceedings of the International Astronomical Union / Volume 13 / Issue S335 / July 2017
    Published online by Cambridge University Press:
    24 July 2018, pp. 197-200
    Print publication:
    July 2017
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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.