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Quantification of magnetosphere–ionosphere coupling timescales using mutual information : response of terrestrial radio emissions and ionospheric–magnetospheric currents
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Fogg, Alexandra Ruth, Jackman, Caitríona M., Chapman, Sandra C., Waters, James E., Bergin, Aisling, Lamy, Laurent, Issautier, Karine, Cecconi, Baptiste and Bonnin, Xavier (2024) Quantification of magnetosphere–ionosphere coupling timescales using mutual information : response of terrestrial radio emissions and ionospheric–magnetospheric currents. Nonlinear Processes in Geophysics, 31 (2). pp. 195-206. doi:10.5194/npg-31-195-2024 ISSN 1023-5809.
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Official URL: http://dx.doi.org/10.5194/npg-31-195-2024
Abstract
Auroral kilometric radiation (AKR) is a terrestrial radio emission excited by the same accelerated electrons which excite auroral emissions. Although it is well correlated with auroral and geomagnetic activity, the coupling timescales between AKR and different magnetospheric or ionospheric regions have yet to be determined. Estimation of these coupling timescales is non-trivial as a result of complex, non-linear processes which rarely occur in isolation. In this study, the mutual information between AKR intensity and different geomagnetic indices is used to assess the correlation between variables. Indices are shifted to different temporal lags relative to AKR intensity, and the lag at which the variables have the most shared information is found. This lag is interpreted as the coupling timescale. The AKR source region receives the effects of a shared driver before the auroral ionosphere. Conversely, the polar ionosphere reacts to a shared driver before the AKR source region. Bow shock interplanetary magnetic field BZ is excited about 1 h before AKR enhancements. This work provides quantitatively determined temporal context to the coupling timelines at Earth. The results suggest that there is a sequence of excitation following the onset of a shared driver: first, the polar ionosphere feels the effects, followed by the AKR source region and then the auroral ionosphere.
Item Type: | Journal Article | |||||||||||||||||||||||||||
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Subjects: | Q Science > QC Physics | |||||||||||||||||||||||||||
Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | |||||||||||||||||||||||||||
Library of Congress Subject Headings (LCSH): | Auroras, Magnetospheric physics, Magnetospheric currents, Magnetospheric radio wave propagation , Radio auroras | |||||||||||||||||||||||||||
Journal or Publication Title: | Nonlinear Processes in Geophysics | |||||||||||||||||||||||||||
Publisher: | Copernicus GmbH | |||||||||||||||||||||||||||
ISSN: | 1023-5809 | |||||||||||||||||||||||||||
Official Date: | 10 April 2024 | |||||||||||||||||||||||||||
Dates: |
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Volume: | 31 | |||||||||||||||||||||||||||
Number: | 2 | |||||||||||||||||||||||||||
Page Range: | pp. 195-206 | |||||||||||||||||||||||||||
DOI: | 10.5194/npg-31-195-2024 | |||||||||||||||||||||||||||
Status: | Peer Reviewed | |||||||||||||||||||||||||||
Publication Status: | Published | |||||||||||||||||||||||||||
Access rights to Published version: | Open Access (Creative Commons) | |||||||||||||||||||||||||||
Date of first compliant deposit: | 26 April 2024 | |||||||||||||||||||||||||||
Date of first compliant Open Access: | 26 April 2024 | |||||||||||||||||||||||||||
RIOXX Funder/Project Grant: |
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