Publication: Preferential amplification of rising versus falling frequency whistler mode signals
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KU Authors
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Li, J. D.
Harid, V.
Spasojevic, M.
Golkowski, M.
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NO
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Abstract
Analysis of ground-based ELF/VLF observations of injected whistler mode waves from the 1986 Siple Station experiment demonstrates the preferential magnetospheric amplification of rising over descending frequency-time ramps. From examining conjugate region receptions of 1 kHz/s frequency-time ramps, we find that rising ramps generate an average total power 1.9 times higher than that of falling frequency ramps when both are observed during a transmission. And in 17% of receptions, only rising ramps are observed above the noise floor. Furthermore, the amplification ratio inversely correlates with the noise and total signal power. Using a narrowband Vlasov-Maxwell numerical simulation, we explore the preferential amplification due to differences in linear growth rate as a function of frequency, relative to the frequency which maximizes the linear growth rate for a given anisotropy, and in nonlinear phase trapping. These results contribute to the understanding of magnetospheric wave amplification and the preference for structured rising elements in chorus.
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Publisher
American Geophysical Union (AGU)
Subject
Multidisciplinary geosciences, Geology
Citation
Has Part
Source
Geophysical Research Letters
Book Series Title
Edition
DOI
10.1002/2014GL062359