Detailed Properties of Equatorial Noise With Quasiperiodic Modulation

0501806 - ÚFA 2019 RIV US eng J - Článek v odborném periodiku
Němec, F. - Santolík, Ondřej - Hayosh, Mykhaylo - Darrouzet, F. - Cornilleau-Wehrlin, N.
Detailed Properties of Equatorial Noise With Quasiperiodic Modulation.
Journal of Geophysical Research-Space Physics. Roč. 123, č. 7 (2018), s. 5344-5355. ISSN 2169-9380. E-ISSN 2169-9402
Grant CEP: GA MŠMT(CZ) LH15304
Grant ostatní: AV ČR(CZ) AP1401
Program: Akademická prémie - Praemium Academiae
Institucionální podpora: RVO:68378289
Klíčová slova: electron butterfly distributions * Van Allen probes * proton ring distributions * fast magnetosonic waves * whistler-mode waves * ELF-VLF emissions * cluster spacecraft * DEMETER spacecraft * spatiotemporal variability * inner magnetosphere
Obor OECD: Fluids and plasma physics (including surface physics)
Impakt faktor: 2.821, rok: 2018
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018JA025382

Equatorial noise (EN) emissions are electromagnetic waves observed routinely in the equatorial region of the inner magnetosphere. Although they are typically continuous in time, they sometimes exhibit a quasiperiodic (QP) time modulation of the wave intensity, with modulation periods on the order of minutes. We perform a detailed analysis of 118 EN events with the QP modulation. The events are observed preferentially outside the plasmasphere. We determine the times and frequencies of individual QP elements forming the events. Apart from the event modulation period, this allows us to characterize the intensity and the frequency drift of individual QP wave elements. It is shown that the element intensity peaks at the magnetic equator. The modulation period within a single event is usually quite stable, with variations lower than 25% of the median value in the vast majority of cases. The events with shorter modulation periods are typically more intense, and they tend to have larger frequency drifts. These relations resemble the relations formerly revealed for extra low frequency/very low frequency quasiperiodic emissions, suggesting that the origin of the QP modulation of the wave intensity of EN and ELF/VLF emissions might be similar.
Trvalý link: http://hdl.handle.net/11104/0293793