Observations of multiharmonic ion-cyclotron waves due to inverse ion-cyclotron damping in the northern magnetospheric cusp
Number of Authors: 3
2016 (English)In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007Article in journal (Refereed) Epub ahead of print
We present a case study of inverse ion-cyclotron damping taking place in the northern terrestrial magnetospheric cusp, exciting waves at the ion-cyclotron frequency and its harmonics. The ion-cyclotron waves are primarily seen as peaks in the magnetic-field spectral densities. The corresponding peaks in the electric-field spectral densities are not as profound, suggesting a background electric field noise or other processes of wave generation causing the electric spectral densities to smoothen out more compared to the magnetic counterpart. The required condition for inverse ion-cyclotron damping is a velocity shear in the magnetic field-aligned ion-bulk flow, and this condition is often naturally met for magnetosheath influx in the northern magnetospheric cusp, just as in the presented case. We note that some ion-cyclotron wave activity is present in a few similar shear events in the southern cusp, which indicates that other mechanisms generating ion-cyclotron waves may also be present during such conditions.
Place, publisher, year, edition, pages
Research subject Atmospheric science
IdentifiersURN: urn:nbn:se:ltu:diva-61214DOI: 10.1002/2016GL071680OAI: oai:DiVA.org:ltu-61214DiVA: diva2:1058998