Amplitudes and frequency sweep rates of wave packets of whistler-mode chorus observed by the Cluster spacecraft

0427202 - ÚFA 2015 US eng A - Abstrakt
Macúšová, E. - Santolík, Ondřej - Pickett, J. S. - Gurnett, D. A. - Cornilleau-Wehrlin, N. - Demekhov, A. G. - Titova, E. E.
Amplitudes and frequency sweep rates of wave packets of whistler-mode chorus observed by the Cluster spacecraft.
AGU Fall Meeting : abstracts. s. l: American Geophysical Union, 2013.
[AGU Fall Meeting 2013. 09.12.2013-13.12.2013, San Francisco]
Institucionální podpora: RVO:68378289
Klíčová slova: plasma waves and instabilities * radiation belts * magnetospheric physics
Kód oboru RIV: DG - Vědy o atmosféře, meteorologie
http://abstractsearch.agu.org/meetings/2013/FM/sections/SM/sessions/SM43A/abstracts/SM43A-2252.html

Whistler-mode chorus is one of the most intense electromagnetic wave emissions observed in the inner magnetosphere, usually outside the plasmasphere. These waves play an important role in wave-particle interactions. They are usually generated close to the geomagnetic equator in a wide range of L-shells, and they propagate toward larger magnetic latitudes. Whistler-mode chorus is sometimes composed of two frequency bands separated by a gap at one half of the electron cyclotron frequency. At short time scales (on the order of hundreds of milliseconds) chorus consist of different discrete spectral shapes: rising tones, falling tones, constant frequency tones, and hooks. Our survey is based on high time resolution measurements collected by the WBD instrument onboard four Cluster spacecraft. We analyze time intervals containing different types of spectral shapes occurring at different L-shells, and at different latitudes relative to the chorus source region, as it is determined from measurements of the STAFF-SA instrument. Each of these events includes a large number of individual wave packets (between a few hundreds to a few thousands). For each individual wave packet we determine the frequency sweep rate and the average amplitude. Our results confirm previous conclusions of numerical simulations, theoretical predictions, and case studies showing that the amplitude of chorus wave packets increases with an increasing frequency sweep rate. The amplitude also increases as the wave forming chorus propagate away from the equator. The scatter of obtained values of frequency sweep rates and amplitudes is much larger closer to the Earth than at larger radial distances. This work receives EU support through the FP7-Space grant agreement no 284520 for the MAARBLE collaborative research project.
Trvalý link: http://hdl.handle.net/11104/0232811