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| Titel |
The use of various interplanetary scintillation indices within geomagnetic forecasts |
| VerfasserIn |
E. A. Lucek, T. D. G. Clark, V. Moore |
| 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 ; 14, no. 2 ; Nr. 14, no. 2, S.139-148 |
| Datensatznummer |
250012164
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| Publikation (Nr.) |
 copernicus.org/angeo-14-139-1996.pdf |
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| Zusammenfassung |
| Interplanetary scintillation (IPS), the
twinkling of small angular diameter radio sources, is caused by the interaction
of the signal with small-scale plasma irregularities in the solar wind. The
technique may be used to sense remotely the near-Earth heliosphere and
observations of a sufficiently large number of sources may be used to track
large-scale disturbances as they propagate from close to the Sun to the Earth.
Therefore, such observations have potential for use within geomagnetic
forecasts. We use daily data from the Mullard Radio Astronomy Observatory, made
available through the World Data Centre, to test the success of geomagnetic
forecasts based on IPS observations. The approach discussed here was based on
the reduction of the information in a map to a single number or series of
numbers. The advantages of an index of this nature are that it may be produced
routinely and that it could ideally forecast both the occurrence and intensity
of geomagnetic activity. We start from an index that has already been described
in the literature, INDEX35. On the basis of visual examination of the
data in a full skymap format modifications were made to the way in which the
index was calculated. It was hoped that these would lead to an improvement in
its forecasting ability. Here we assess the forecasting potential of the index
using the value of the correlation coefficient between daily Ap and the
IPS index, with IPS leading by 1 day. We also compare the forecast based on the
IPS index with forecasts of Ap currently released by the Space
Environment Services Center (SESC). Although we find that the maximum
improvement achieved is small, and does not represent a significant advance in
forecasting ability, the IPS forecasts at this phase of the solar cycle are of a
similar quality to those made by SESC. |
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