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| Titel |
Automated identification and tracking of polar-cap plasma patches at solar minimum |
| VerfasserIn |
R. Burston, K. Hodges, I. Astin, P. T. Jayachandran |
| 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. 3 ; Nr. 32, no. 3 (2014-03-11), S.197-206 |
| Datensatznummer |
250121033
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| Publikation (Nr.) |
 copernicus.org/angeo-32-197-2014.pdf |
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| Zusammenfassung |
| A method of automatically identifying and tracking polar-cap plasma patches,
utilising data inversion and feature-tracking methods, is presented. A
well-established and widely used 4-D ionospheric imaging algorithm, the
Multi-Instrument Data Assimilation System (MIDAS), inverts slant total
electron content (TEC) data from ground-based Global Navigation Satellite
System (GNSS) receivers to produce images of the free electron distribution
in the polar-cap ionosphere. These are integrated to form vertical TEC maps.
A flexible feature-tracking algorithm, TRACK, previously used extensively in
meteorological storm-tracking studies is used to identify and track maxima in
the resulting 2-D data fields. Various criteria are used to discriminate
between genuine patches and "false-positive" maxima such as the
continuously moving day-side maximum, which results from the Earth's rotation
rather than plasma motion. Results for a 12-month period at solar minimum,
when extensive validation data are available, are presented. The method
identifies 71 separate structures consistent with patch motion during this
time. The limitations of solar minimum and the consequent small number of
patches make climatological inferences difficult, but the feasibility of the
method for patches larger than approximately 500 km in scale is demonstrated
and a larger study incorporating other parts of the solar cycle is warranted.
Possible further optimisation of discrimination criteria, particularly
regarding the definition of a patch in terms of its plasma concentration
enhancement over the surrounding background, may improve results. |
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