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| Titel |
A study of Traveling Ionospheric Disturbances and Atmospheric Gravity Waves using EISCAT Svalbard Radar IPY-data |
| VerfasserIn |
A. Vlasov, K. Kauristie, M. Kamp, J.-P. Luntama, A. Pogoreltsev |
| 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 ; 29, no. 11 ; Nr. 29, no. 11 (2011-11-24), S.2101-2116 |
| Datensatznummer |
250017130
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| Publikation (Nr.) |
 copernicus.org/angeo-29-2101-2011.pdf |
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| Zusammenfassung |
| We present a statistical study of Traveling Ionospheric
Disturbances (TIDs) as observed by the EISCAT Svalbard Radar (ESR) during the
continuous IPY-run (March 2007–February 2008) with field-aligned
measurements. We have developed a semi-automatic routine for searching and
extracting Atmospheric Gravity Wave (AGW) activity. The collected data shows
that AGW-TID signatures are common in the high-latitude ionosphere especially
in the field-aligned ion velocity data (244 cases of AGW-TID signatures in
daily records), but they can be observed also in electron density (26 cases),
electron temperature (12 cases) and ion temperature (26 cases). During the
IPY campaign (in solar minimum conditions) AGW-TID events appear more
frequently during summer months than during the winter months. It remains
still as a topic for future studies whether the observed seasonal variation
is natural or caused by seasonal variation in the performance of the
observational method that we use (AGW-TID signature may be more pronounced in
a dense ionosphere). In our AGW-TID dataset the distribution of the
oscillation periods has two peaks, one around 0.5–0.7 h and the other
around 1.1–1.3 h. The diurnal occurrence rate has a deep minimum in the
region of magnetic midnight, which might be partly explained by irregular
auroral activity obscuring the TID signatures from our detection routines. As
both the period and horizontal phase speed estimates (as derived from the
classical AGW dispersion relation) show values typical both for large scale
TIDs and mesoscale TIDs it is difficult to distinguish whether the generator
for high-latitude AGW-TIDs resides typically in the troposphere or in the
near-Earth space. The results of our statistical analysis give anyway some
valuable reference information for the future efforts to learn more about the
dominating TID source mechanisms in polar cap conditions, and to improve AGW
simulations. |
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