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Ann. Geophys., 23, 3095-3101, 2005
www.ann-geophys.net/23/3095/2005/
© European Geosciences Union 2005
Predictions of local ground geomagnetic field fluctuations during the 7-10 November 2004 events studied with solar wind driven models
P. Wintoft1, M. Wik1, H. Lundstedt1, and L. Eliasson2
1Swedish Institute of Space Physics, Lund, Sweden
2Swedish Institute of Space Physics, Kiruna, Sweden
Abstract. The 7-10 November 2004 period contains two events for which the local ground
magnetic field was severely disturbed and simultaneously, the solar wind
displayed several shocks and negative Bz periods. Using empirical models
the 10-min RMS and at Brorfelde (BFE, 11.67° E,
55.63° N), Denmark, are predicted. The models are recurrent neural
networks with 10-min solar wind plasma and magnetic field data as inputs.
The predictions show a good agreement during 7 November, up until around noon
on 8 November, after which the predictions become significantly poorer. The
correlations between observed and predicted log RMS is 0.77 during
7-8 November but drops to 0.38 during 9-10 November. For RMS the correlations
for the two periods are 0.71 and 0.41, respectively. Studying the solar wind
data for other L1-spacecraft (WIND and SOHO) it seems that the ACE data have
a better agreement to the near-Earth solar wind during the first two days as
compared to the last two days. Thus, the accuracy of the predictions depends
on the location of the spacecraft and the solar wind flow direction. Another
finding, for the events studied here, is that the and models
showed a very different dependence on Bz. The model is almost
independent of the solar wind magnetic field Bz, except at times when
Bz is exceptionally large or when the overall activity is low. On the
contrary, the model shows a strong dependence on Bz at all times.
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