Preferential amplification of rising versus falling frequency whistler mode signals
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.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jan 20, 2015
- Source ID
- 10.1002/2014gl062359
Entities
People
- J. D. Li
- M. Spasojevic
- Mark Gołkowski
- U. S. Inan
- Vijay Harid
Organizations
- Air Force Research Laboratory
- Koç University
- Stanford University