EXTREMELY INTENSE ELF MAGNETOSONIC WAVES AND A POSSIBLE NEW SOURCE FOR PLASMASPHERIC HISS: POLAR OBSERVATIONS

0431033 - ÚFA 2015 US eng A - Abstrakt
Tsurutani, B. T. - Pickett, J. S. - Verkhoglyadova, O. P. - Santolík, Ondřej - Lakhina, G. S.
EXTREMELY INTENSE ELF MAGNETOSONIC WAVES AND A POSSIBLE NEW SOURCE FOR PLASMASPHERIC HISS: POLAR OBSERVATIONS.
AGU Fall Meeting 2013. San Francisco: AGU, 2013. SM23C-02.
[AGU Fall Meeting 2013. 09.12.2013-13.12.2013, San Francisco]
Institucionální podpora: RVO:68378289
Klíčová slova: Plasmasphere * Plasma waves and instabilities * Radiation belts * Kinetic waves and instabilities
Kód oboru RIV: BL - Fyzika plazmatu a výboje v plynech
http://abstractsearch.agu.org/meetings/2013/FM/sections/SM/sessions/SM23C/abstracts/SM23C-02.html

From a survey of Polar plasma waves conducted over the interval 1 April, 1996 to 4 April, 1997, at and inside the plasmasphere, magnetosonic waves were detected at all local times with a slight preference of occurrence in the postmidnight sector (a ~20% normalized occurrence rate). The waves occurred primarily during heightened geomagnetic activity. Wave occurrence (and intensities) peaked at ~±5° of the magnetic equator, with half-maxima at ~±10°. An extreme magnetosonic wave intensity event of amplitude Bw = ~± 1 nT and Ew = ~± 25 mV/m was detected during the survey period. The event occurred at the equatorial plasmapause (MLAT = -0.5°, L = 3.5), during a substorm/convection event (AE = 624 nT; SYM-H = -33 nT) near local midnight (0022MLT). The probability of being at exactly the right location at the perfect time is quite small, thus even higher intensity wave events may have occurred in the past, but were missed by spacecraft observations. For other wave events, magnetosonic waves were also detected as far from the equator as 20° and -60° MLAT, but at lower intensities. The wave magnetic component oscillations are along B0, the ambient magnetic field direction, while the electric component oscillations are orthogonal to B0. There is a ~ 90° phase lag between the B and E components. The magnetosonic wave amplitudes decreased at locations further from the magnetic equator, while transverse whistler mode wave amplitudes increased. It is thus possible that either charged particle interactions with the magnetosonic waves or direct mode conversion is leading to the generation of the transverse whistler mode waves. Thus this mechanism may be a new source for the low frequency component of plasmaspheric hiss, adding to other sources, previously discussed in the literature.
Trvalý link: http://hdl.handle.net/11104/0235678