Journal article
Generation of unusually low frequency plasmaspheric hiss
Geophysical research letters, Vol.41(16), pp.5702-5709
08/28/2014
DOI: 10.1002/2014GL060628
Abstract
It has been reported from Van Allen Probe observations that plasmaspheric hiss intensification in the outer plasmasphere, associated with a substorm injection on 30 September 2012, occurred with a peak frequency near 100 Hz, well below the typical plasmaspheric hiss frequency range, extending down to ∼20 Hz. We examine this event of unusually low frequency plasmaspheric hiss to understand its generation mechanism. Quantitative analysis is performed by simulating wave raypaths via the HOTRAY ray tracing code with measured plasma density and calculating raypath-integrated wave gain evaluated using the measured energetic electron distribution. We demonstrate that the growth rate due to substorm-injected electrons is positive but rather weak, leading to small wave gain (∼10 dB) during a single equatorial crossing. Propagation characteristics aided by the sharp density gradient associated with the plasmapause, however, can enable these low-frequency waves to undergo cyclic raypaths, which return to the unstable region leading to repeated amplification to yield sufficient net wave gain (>40 dB) to allow waves to grow from the thermal noise.
Details
- Title: Subtitle
- Generation of unusually low frequency plasmaspheric hiss
- Creators
- Lunjin Chen - University of Texas at DallasC. A Kletzing - University of IowaRichard M Thorne - University of California, Los AngelesW. S Kurth - University of IowaJacob Bortnik - University of California, Los AngelesG. B Hospodarsky - University of IowaWen Li - University of California, Los AngelesRichard B Horne - Natural Environment Research CouncilG. D Reeves - Los Alamos National LaboratoryH. E Spence - University of New HampshireJ. B Blake - The Aerospace CorporationJ. F Fennell - The Aerospace Corporation
- Resource Type
- Journal article
- Publication Details
- Geophysical research letters, Vol.41(16), pp.5702-5709
- Publisher
- Blackwell Publishing Ltd
- DOI
- 10.1002/2014GL060628
- ISSN
- 0094-8276
- eISSN
- 1944-8007
- Number of pages
- 8
- Language
- English
- Date published
- 08/28/2014
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984199728902771
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