 |
| Titel |
Extreme ion heating in the dayside ionosphere in response to the arrival of a coronal mass ejection on 12 March 2012 |
| VerfasserIn |
H. Fujiwara, S. Nozawa, Y. Ogawa, R. Kataoka, Y. Miyoshi, H. Jin, H. Shinagawa |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
0992-7689
|
| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 32, no. 7 ; Nr. 32, no. 7 (2014-07-23), S.831-839 |
| Datensatznummer |
250121084
|
| Publikation (Nr.) |
 copernicus.org/angeo-32-831-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| Simultaneous measurements of the polar ionosphere with the European Incoherent Scatter (EISCAT) ultra high frequency (UHF) radar
at Tromsø and the EISCAT Svalbard radar (ESR) at Longyearbyen were made
during 07:00–12:00 UT on 12 March 2012. During the period, the Advanced Composition Explorer (ACE) spacecraft
observed changes in the solar wind which were due to the arrival of
coronal mass ejection (CME) effects associated with the 10 March M8.4 X-ray
event. The solar wind showed two-step variations which caused strong
ionospheric heating. First, the arrival of shock structures in the solar wind
with enhancements of density and velocity, and a negative interplanetary magnetic field (IMF)-Bz component
caused strong ionospheric heating around Longyearbyen; the ion temperature at
about 300 km increased from about 1100 to 3400 K over Longyearbyen while
that over Tromsø increased from about 1050 to 1200 K. After the passage
of the shock structures, the IMF-Bz component showed positive values and
the solar wind speed and density also decreased. The second strong
ionospheric heating occurred after the IMF-Bz component showed
negative values again; the negative values lasted for more than
1.5 h. This solar wind variation caused stronger heating of the ionosphere in
the lower latitudes than higher latitudes, suggesting expansion of the auroral
oval/heating region to the lower latitude region. This study shows an example
of the CME-induced dayside ionospheric heating: a short-duration and very large rise in the ion temperature which was closely related to the polar
cap size and polar cap potential variations as a result of interaction
between the solar wind and the magnetosphere. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|