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Titel |
Reconstruction of geomagnetic activity and near-Earth interplanetary conditions over the past 167 yr – Part 4: Near-Earth solar wind speed, IMF, and open solar flux |
VerfasserIn |
M. Lockwood, H. Nevanlinna, L. Barnard, M. J. Owens, R. G. Harrison, A. P. Rouillard, C. J. Scott |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
0992-7689
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Digitales Dokument |
URL |
Erschienen |
In: Annales Geophysicae ; 32, no. 4 ; Nr. 32, no. 4 (2014-04-11), S.383-399 |
Datensatznummer |
250121048
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Publikation (Nr.) |
copernicus.org/angeo-32-383-2014.pdf |
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Zusammenfassung |
In the concluding paper of this tetralogy, we here use the different
geomagnetic activity indices to reconstruct the near-Earth interplanetary
magnetic field (IMF) and solar wind flow speed, as well as the open solar
flux (OSF) from 1845 to the present day. The differences in how the various
indices vary with near-Earth interplanetary parameters, which are here
exploited to separate the effects of the IMF and solar wind speed, are shown
to be statistically significant at the 93% level or above.
Reconstructions are made using four combinations of different indices,
compiled using different data and different algorithms, and the results are
almost identical for all parameters. The correction to the aa index required
is discussed by comparison with the Ap index from a more extensive
network of mid-latitude stations. Data from the Helsinki magnetometer station
is used to extend the aa index back to 1845 and the results confirmed by
comparison with the nearby St Petersburg observatory. The optimum variations,
using all available long-term geomagnetic indices, of the near-Earth IMF and
solar wind speed, and of the open solar flux, are presented; all with
±2σ uncertainties computed using the Monte Carlo technique
outlined in the earlier papers. The open solar flux variation derived is
shown to be very similar indeed to that obtained using the method of Lockwood
et al. (1999). |
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