Chorus and chorus-like emissions seen by the ionospheric satellite DEMETER

0462960 - ÚFA 2017 RIV US eng J - Článek v odborném periodiku
Parrot, M. - Santolík, Ondřej - Němec, František
Chorus and chorus-like emissions seen by the ionospheric satellite DEMETER.
Journal of Geophysical Research-Space Physics. Roč. 121, č. 4 (2016), s. 3781-3792. ISSN 2169-9380. E-ISSN 2169-9402
Grant CEP: GA ČR(CZ) GA14-31899S; GA MŠMT(CZ) LH15304
Institucionální podpora: RVO:68378289
Klíčová slova: chorus * ionosphere
Kód oboru RIV: BL - Fyzika plazmatu a výboje v plynech
Impakt faktor: 2.733, rok: 2016
http://onlinelibrary.wiley.com/doi/10.1002/2015JA022286/full

A lot of different emissions have been detected by the low-altitude satellite DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions), and the aim of this paper is to study extremely low frequency (ELF) electromagnetic waves with elements drifting in frequency. It is shown that only some of them can be considered as usual chorus. These chorus elements are emitted in the equatorial plane, and their propagation analysis indicates that they are going downward at low altitudes in the ionosphere to be detected by the satellite. The study of one remarkable event recorded along the same orbit in both the Northern and the Southern Hemispheres on 8 May 2008 indicates that this propagation mechanism is reinforced at the location of the ionospheric trough, which corresponds to the plasmapause at higher altitudes. It has been observed that usual chorus elements at low frequencies are always in a frequency band which overlaps with a hiss band limited by a frequency cutoff close to the proton gyrofrequency. Other drifting elements can be attributed to emissions triggered by PLHR (power line harmonic radiation). It means that without a high-resolution spectral analysis, chorus-like elements triggered by PLHR can be wrongly considered as natural chorus. These drifting elements can also appear as filamentary structures emerging at the upper frequencies of a hiss band or quasiperiodic emissions. There are events where the elements even have certain similarities to quasiperiodic emissions. The difference between these elements and the chorus emissions will be emphasized.
Trvalý link: http://hdl.handle.net/11104/0263190