Chorus rising tones seen inside their source region by the THEMIS spacecraft

0446624 - ÚFA 2016 CZ eng A - Abstrakt
Taubenschuss, Ulrich - Graham, D. - Santolík, Ondřej - Khotyaintsev, Y. - Vaivads, A. - Fu, H. - Li, W. - Breuillard, H. - Tomori, Alexander - Contel Le, O. - Angelopoulos, V.
Chorus rising tones seen inside their source region by the THEMIS spacecraft.
26th IUGG General Assembly 2015. Earth and Environmental Sciences for Future Generations : abstracts. Prague: International Union of Geodesy and Geophysics, 2015. A21p-262.
[Earth and Environmental Sciences for Future Generations. General Assembly of International Union of Geodesy and Geophysics /26./. 22.06.2015-02.07.2015, Prague]
Institucionální podpora: RVO:68378289
Kód oboru RIV: DG - Vědy o atmosféře, meteorologie
http://www.iugg2015prague.com/abstractcd/data/HtmlApp/main.html#0

The THEMIS-D (Time History of Events and Macroscale Interactions during Substorms) spacecraft crossed an active equatorial source region of whistler mode chorus rising tones on 23 October, 2008. We present detailed electric, magnetic, and particle measurements for this event. Based on the observations, we evaluate linear and nonlinear generation mechanisms. We find that continuous chorus bursts across 0.5 f_c (half of the local electron cyclotron frequency) can be explained through linear wave growth only for higher cold plasma densities than their actual estimates from the spacecraft potential. We, however, do not exclude the possibility of short-term density enhancements on time scales less than the time resolution of our density estimates. Moreover, the conditions inside the source region provide strong evidence that on top of linear growth, nonlinear wave growth mechanisms are active. The appearance of a gap at 0.5 f_c in chorus spectra of this event seems to be sensitive to the ratio of hot to cold electron density. The proximity of THEMIS-D to the source region suggests that the gap emerges already inside the source rather than being created during long-distance wave propagation away from the source.
Trvalý link: http://hdl.handle.net/11104/0248909