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| Titel |
Variations in the Upper Atmosphere over Kharkov during Severe Magnetic Storms |
| VerfasserIn |
Vitaliy Taran, Mykhaylo Lyashenko, Leonid Chernogor, Igor Domnin, Yelena Grigorenko, Valeriy Pulyayev |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250031860
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| Zusammenfassung |
| We study the features of well pronounced negative ionospheric disturbances accompanying
severe magnetic storms on 25 September 1998, 29–30 May 2003 and 7–10 November 2004
(Kp -¥Â 8) as observed by the Kharkov incoherent scatter radar (49.6ºN, 36.3ºE). Among
considered features there are depletion in electron density by a factor of 3.5–7, uplifting of
ionospheric F2 region by more than 100 km, unusual nighttime heating of plasma up to
daytime values of ion and electron temperatures, and infringements of plasma transfer
process and of thermal balance in the ionosphere – plasmasphere system. During the
September 1998 storm, an unusual increase in the upward plasma drift velocity was
registered in the morning sector. It was shown that such disturbance could be caused by
superposition of the effects of two sources: equatorward storm-induced surge in the neutral
wind and/or electric field pulse, which both were generated by bursts of substorm activity. On
29–30 May 2003 during the main storm phase a depletion in the relative density of hydrogen
ions by more than an order of magnitude with its further increasing during the recovery
storm phase was revealed that could manifest an emptying of the magnetic flux tube
over the Kharkov radar and its subsequent filling. The effects usually observed in
the high-latitude ionosphere, including the oblique coherent backscatters, at that
even in the daytime, are detected during the main phase of the 10 November 2004
storm. These phenomena are explained in terms of thermospheric disturbances,
Joule heating, particle precipitation, penetration of magnetospheric electric fields to
midlatitudes, and the shift of auroral oval and related structures towards the radar
latitude. The examine results allowed distinguish the common regularities and specific
peculiarities in the evolution of these disturbances at midlatitudes of the Central Europe. |
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