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Narrow‐band extremely low frequency (ELF) wave phenomena observed at South Pole Station
Author(s) -
Kim Hyomin,
Lessard Marc R.,
LaBelle James,
Johnson Jay R.
Publication year - 2006
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 - 10.1029/2005gl023638
Subject(s) - whistler , physics , extremely low frequency , very low frequency , harmonics , low frequency , frequency band , ultra low frequency , radio spectrum , geophysics , bandwidth (computing) , computational physics , magnetic field , acoustics , telecommunications , astronomy , quantum mechanics , voltage , computer science
Extremely low frequency (ELF) magnetic pulsations which show a whistler‐like spectral structure have been measured at South Pole Station. An initial survey of the first 70 days of data revealed narrow‐band ELF pulsations with slowly varying frequency over time. The narrow‐band (a few Hz) signatures maintain their bandwidth as their frequencies decrease from 110 to 50 Hz (and their second harmonics) over the course of 40–90 s. Although the narrow‐band ELF waves have a signature somewhat similar to very low frequency (VLF) whistlers, their duration and frequency range are much different from those of whistlers; they also show an unusual characteristic where their frequency often increases before it decreases. These events show a peak in their magnetic local time (MLT) occurrence distribution near the pre‐midnight region, a result that contrasts sharply with the only three previously published studies of these waves. Two possibilities of generation mechanism are discussed.