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Hints on the Multiscale Nature of Geomagnetic Field Fluctuations During Quiet and Disturbed Periods

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Papers from SWICo members

L. Santarelli, P. De Michelis, G. Consolini

We analyse the short timescale fluctuations (τ < 200 min) of the magnetic signals recorded at 78 ground stations from 13 to 31 March 2015, focusing our attention on sources which are external to the Earth, that is, due to current systems flowing in the ionosphere and magnetosphere, and investigating their dependence on magnetic latitude, magnetic local time, and geomagnetic activity. We find that, at geomagnetic latitudes >|60°|, such fluctuations constitute more than 30% of the external magnetic field, and their maximum contribution occurs along the auroral oval suggesting that they are mainly triggered by the ionospheric electric current systems active in these regions.

Daily polar view maps of the ratio between the contribution of the average energy (in terms of variance) of the fast fluctuating part of the magnetic field horizontal component (H) and the average energy associated with the total fluctuating signal. Data are reported in magnetic latitude (from 20° to 90°) and MLT coordinate system and refer to 3 days characterized by different geomagnetic activity levels.

These short timescale magnetic fluctuations are very relevant in contributing to the prediction of geomagnetically induced currents in the auroral zones.

Publication: L. Santarelli, P. De Michelis, G. Consolini, Hints of the Multiscale Nature of Geomagnetic Field Fluctuations during Quiet and Disturbed Periods, J. Geophys. Res.: Space Physics, 126 (5), 2021. https://doi.org/10.1029/2020JA028596