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Statistics of temporal variations in the auroral electrojets over Fennoscandia
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  • Simon James Walker,
  • Karl Laundal,
  • Jone Peter Reistad,
  • Anders Ohma,
  • Hatch Spencer Mark
Simon James Walker
Univerisity of Bergen

Corresponding Author:simon_james_walker@hotmail.co.uk

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Karl Laundal
University in Bergen
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Jone Peter Reistad
Birkeland Centre for Space Science, University of Bergen
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Anders Ohma
Birkeland Centre for Space Science, Department of Physics and Technology, University of Bergen
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Hatch Spencer Mark
Birkeland Centre for Space Science
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We present the implementation of an improved technique to coherently model the high-latitude ionospheric equivalent current. By using a favourable and fixed selection of 20 ground magnetometers in Fennoscandia, we present a method based on Spherical Elementary Current Systems (SECS) to model the currents coherently during 2000–2020. Due to the north-south extent of the ground stations used, we focus on the model output along the 105 magnetic meridian. In addition to the fixed data locations and SECS analysis grid, our improvements involve taking into account a priori knowledge of the large-scale current systems to improve the robustness of solving the underdetermined inverse problem. We account for contributions from ground induced currents assuming so-called mirror currents. An advantage of this data set over existing empirical models of ionospheric currents is the 1-min output resolution. High temporal resolution enables investigation of temporal changes in the magnetic field. We present an analysis of statistical properties of where (in magnetic latitude and local time) and at what rate (∂Br /∂t) the radial magnetic field component fluctuates. We show that ∂Br /∂t, which is equivalent to the radial component of the curl of the induced electric field, is dependent on latitude, local time, and solar cycle. Other applications of the presented data set are also highlighted, including investigations of how Ultra Low Frequency oscillations in ground magnetic perturbations vary in space and time.