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Source of the low‐altitude hiss in the ionosphere
Author(s) -
Chen Lunjin,
Santolík Ondrej,
Hajoš Mychajlo,
Zheng Liheng,
Zhima Zeren,
Heelis Roderick,
Hanzelka Miroslav,
Horne Richard B.,
Parrot Michel
Publication year - 2017
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl072181
Subject(s) - hiss , ionosphere , whistler , physics , altitude (triangle) , geophysics , latitude , very low frequency , atmospheric sciences , geology , plasma , electron , astronomy , nuclear physics , geometry , mathematics
Abstract We analyze the propagation properties of low‐altitude hiss emission in the ionosphere observed by DEMETER (Detection of Electromagnetic Emissions Transmitted from Earthquake Regions). There exist two types of low‐altitude hiss: type I emission at high latitude is characterized by vertically downward propagation and broadband spectra, while type II emission at low latitude is featured with equatorward propagation and a narrower frequency band above ∼ f cH+ . Our ray tracing simulation demonstrates that both types of the low‐altitude hiss at different latitude are connected and they originate from plasmaspheric hiss and in part chorus emission. Type I emission represents magnetospheric whistler emission that accesses the ionosphere. Equatorward propagation associated with type II emission is a consequence of wave trapping mechanisms in the ionosphere. Two different wave trapping mechanisms are identified to explain the equatorial propagation of Type II emission; one is associated with the proximity of wave frequency and local proton cyclotron frequency, while the other occurs near the ionospheric density peak.