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The nonlinear response of AE to the IMF B S driver: A spectral break at 5 hours
Author(s) -
Tsurutani Bruce T.,
Sugiura Masahisa,
Iyemori Toshihiko,
Goldstein Bruce E.,
Gonzalez Walter D.,
Akasofu Syun I.,
Smith Edward J.
Publication year - 1990
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/gl017i003p00279
Subject(s) - physics , saturation (graph theory) , spectral density , nonlinear system , spectral line , ionosphere , astrophysics , atomic physics , mathematics , geophysics , statistics , quantum mechanics , combinatorics , astronomy
We demonstrate the existence of a sharp break in the power spectrum of AE at ∼ 5 hours. At frequencies below the break, AE has a ∼ f −1.0 dependence, and at higher frequencies it has a f −2.2 to f −2.4 dependence. The power spectrum of the IMF B s for the same time interval has a ∼ f −1.4 dependence with no spectral breaks or peaks. Thus, at frequencies above the break, the power in AE varies as f −0.5 to f −0.8 times the power in B s and at low frequencies it ranges from being f 0 (frequency independent) to a f +0.4 times the power in B s . Several possible explanations of the nonlinear response of AE to the IMF B s driver are briefly discussed, including: 1) variable ionospheric conductivity (increasing with B s ) for the high frequency regime, and 2) several AE saturation mechanisms for the low frequency regime.