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Overview of Emic Triggered Chorus Emissions in Cluster Data
- Source :
- AGU Fall meeting 2010, AGU Fall meeting 2010, Dec 2010, San Francisco, California, United States. pp.02
- Publication Year :
- 2010
- Publisher :
- HAL CCSD, 2010.
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Abstract
- International audience; Electromagnetic ion cyclotron (EMIC) triggered emissions have been recently observed onboard the Cluster spacecraft close to the plasmapause in the equatorial region of the magnetosphere (Pickett et al., 2010). The nonlinear mechanism of the wave amplification is the same as for the well known whistler-mode chorus emissions (Omura et al., 2010). The EMIC triggered emissions appear as risers: electromagnetic structures that have a positive frequency drift with time. They can thus be considered as the EMIC analogue of rising frequency whistler-mode chorus emissions. In addition, they propagate away from the magnetic equator. These EMIC risers are not common in Cluster data. We present an overview of the properties of all the identified cases. Risers can be sorted out in two groups: in the first one the starting frequency of EMIC emissions is close to one half of the local proton gyrofrequency and the risers have a clear left-hand polarization. In the second group the risers have an opposite polarization with a starting frequency close to one half of the He gyrofrequency. Most of the cases have been detected close to 22 MLT (magnetic local time). This dependence will be investigated to determine if it is linked to the orbit effects or if there is a physical cause.
Details
- Language :
- English
- Database :
- OpenAIRE
- Journal :
- AGU Fall meeting 2010, AGU Fall meeting 2010, Dec 2010, San Francisco, California, United States. pp.02
- Accession number :
- edsair.dedup.wf.001..29efa402e22a9f4f2afb0a1978142636