Open AccessResonant ULF absorption at storm time conditions
Author(s) -
В. И. Бадин,
В. И. Бадин
Publication year - 2017
Publication title -
solnečno-zemnaâ fizika
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.11
H-Index - 2
ISSN - 2412-4737
DOI - 10.12737/21428
Subject(s) - physics , doppler effect , radar , computational physics , ionosphere , magnetosphere , magnetic field , geophysics , telecommunications , quantum mechanics , astronomy , computer science
The work deals with ULF radar observations of the high-latitude ionosphere. Doppler data from the Norwegian STARE instrument are analyzed for the moderate magnetic storm observed on December 31, 1999–January 01, 2000. Upon averaging the Doppler signals along radar beams, the spectral power of signals is determined for each beam as a function of frequency ranging from 1 to 10 mHz. Sharp drops (about 10 dB) of spectral powers with frequency are found for all radar beams. A variational analysis of spectral powers is carried out by least squares, with power drops being modeled by stepwise profiles constructed of mean spectral powers preceding and succeeding the drops. Using this variational analysis, the frequency of the power drop is determined for each radar beam. Being averaged over all beams, this frequency is 4.8±0.5 mHz. The results obtained are interpreted as resonant absorption of ultra-low-frequency (ULF) waves occurring on eigenfrequencies of magnetic field lines over wave propagation from the magnetopause deep into the magnetosphere.