Modelling substorm chorus events in terms of dispersive azimuthal drift
2004 (English)In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 22, no 12, 4311-4327 p.Article in journal (Refereed) Published
The Substorm Chorus Event (SCE) is a radio phenomenon observed on the ground after the onset of the substorm expansion phase. It consists of a band of VLF chorus with rising upper and lower cutoff frequencies. These emissions are thought to result from Doppler-shifted cyclotron resonance between whistler mode waves and energetic electrons which drift into a ground station's field of view from an injection site around midnight. The increasing frequency of the emission envelope has been attributed to the combined effects of energy dispersion due to gradient and curvature drifts, and the modification of resonance conditions and variation of the half-gyrofrequency cutoff resulting from the radial component of the E x B drift. A model is presented which accounts for the observed features of the SCE in terms of the growth rate of whistler mode waves due to anisotropy in the electron distribution. This model provides an explanation for the increasing frequency of the SCE lower cutoff, as well as reproducing the general frequency-time signature of the event. In addition, the results place some restrictions on the injected particle source distribution which might lead to a SCE.
Place, publisher, year, edition, pages
2004. Vol. 22, no 12, 4311-4327 p.
space plasma physics, wave-particle interaction, magnetospheric physics, plasma waves and instabilities, storms and substorms
Other Engineering and Technologies
IdentifiersURN: urn:nbn:se:kth:diva-24608DOI: 10.5194/angeo-22-4311-2004ISI: 000226831100025ScopusID: 2-s2.0-13244259601OAI: oai:DiVA.org:kth-24608DiVA: diva2:352238
QC 201009202010-09-202010-09-202010-09-20Bibliographically approved