Ring current influence on auroral electrojet predictions
Geomagnetic storms and substorms develop under strong control of the solar wind. This is demonstrated by the fact that the geomagnetic activity indices <i>Dst</i> and <i>AE</i> can be predicted from the solar wind alone. A consequence of the strong control by a common sour...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
1999-10-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/17/1268/1999/angeo-17-1268-1999.pdf |
| Summary: | Geomagnetic storms and substorms develop
under strong control of the solar wind. This is demonstrated by the fact that
the geomagnetic activity indices <i>Dst</i> and <i>AE</i> can be predicted from
the solar wind alone. A consequence of the strong control by a common source is
that substorm and storm indices tend to be highly correlated. However, a part of
this correlation is likely to be an effect of internal magnetospheric processes,
such as a ring-current modulation of the solar wind-<i>AE</i> relation.
<p style="line-height: 20px;">The present work extends previous studies of nonlinear <i>AE</i>
predictions from the solar wind. It is examined whether the <i>AE</i>
predictions are modulated by the <i>Dst</i> index.This is accomplished by
comparing neural network predictions from <i>Dst</i> and the solar wind, with
predictions from the solar wind alone. Two conclusions are reached: (1) with an
optimal set of solar-wind data available, the <i>AE</i> predictions are not
markedly improved by the <i>Dst</i> input, but (2) the <i>AE</i> predictions are
improved by <i>Dst</i> if less than, or other than, the optimum solar-wind data
are available to the net. It appears that the solar wind-<i>AE</i> relation
described by an optimized neural net is not significantly modified by the
magnetosphere's <i>Dst</i> state. When the solar wind alone is used to predict <i>AE</i>,
the correlation between predicted and observed <i>AE</i> is 0.86, while the
prediction residual is nearly uncorrelated to <i>Dst</i>. Further, the finding
that <i>Dst</i> can partly compensate for missing information on the solar wind,
is of potential importance in operational forecasting where gaps in the stream
of real time solar-wind data are a common occurrence.<br><br><b>Key words. </b>Magnetospheric physics (solar wind ·
magnetosphere interactions; storms and substorms) |
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| ISSN: | 0992-7689 1432-0576 |