Statistical Temporal Variations in the Auroral Electrojet Estimated With Ground Magnetometers in Fennoscandia
Abstract We present the implementation of an improved technique to coherently model the high‐latitude ionospheric equivalent current. Using a fixed selection of 20 ground magnetometers in Fennoscandia, we present a method based on Spherical Elementary Current Systems (SECS) to model the currents coh...
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Wiley
2023-01-01
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| Series: | Space Weather |
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| Online Access: | https://doi.org/10.1029/2022SW003305 |
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| author | Simon Walker Karl Laundal Jone Reistad Anders Ohma Spencer Hatch |
| author_facet | Simon Walker Karl Laundal Jone Reistad Anders Ohma Spencer Hatch |
| author_sort | Simon Walker |
| collection | DOAJ |
| description | Abstract We present the implementation of an improved technique to coherently model the high‐latitude ionospheric equivalent current. Using a 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 magnetometers, we focus on the model output along the 105° magnetic meridian. Our improvements involve fixed data locations and SECS analysis grid and using a priori knowledge of the large‐scale currents improving the robustness of the inverse problem solution. We account for contributions from ground induced currents assuming so‐called mirror currents. This study produces a new data set of divergence‐free (DF) currents and magnetic field perturbations along the 105° magnetic meridian with 1‐min resolution. By comparing averages of the data set with an empirical model of the ionosphere we demonstrate the validity of the data set. We show how our data set, in particular its temporal nature, is distinct from empirical models and other studies. Not only can the temporal evolution of the DF currents and magnetic field perturbations be investigated, but the time derivative of said quantities can be analyzed. For application in ground induced currents, we present the statistical properties of where (in magnetic latitude and local time) and at what rate (∂Br/∂t) the radial magnetic field component fluctuates, a temporal derivative that has received very little attention. We show that ∂Br/∂t is dependent on latitude, local time, and solar cycle. We present other applications such as Ultra Low Frequency Waves monitoring. |
| format | Article |
| id | doaj-art-2b9687415be24a0f8bb9b590c4063cab |
| institution | Kabale University |
| issn | 1542-7390 |
| language | English |
| publishDate | 2023-01-01 |
| publisher | Wiley |
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| spelling | doaj-art-2b9687415be24a0f8bb9b590c4063cab2025-01-14T16:35:23ZengWileySpace Weather1542-73902023-01-01211n/an/a10.1029/2022SW003305Statistical Temporal Variations in the Auroral Electrojet Estimated With Ground Magnetometers in FennoscandiaSimon Walker0Karl Laundal1Jone Reistad2Anders Ohma3Spencer Hatch4Department of Physics and Technology Birkeland Centre for Space Science University of Bergen Bergen NorwayDepartment of Physics and Technology Birkeland Centre for Space Science University of Bergen Bergen NorwayDepartment of Physics and Technology Birkeland Centre for Space Science University of Bergen Bergen NorwayDepartment of Physics and Technology Birkeland Centre for Space Science University of Bergen Bergen NorwayDepartment of Physics and Technology Birkeland Centre for Space Science University of Bergen Bergen NorwayAbstract We present the implementation of an improved technique to coherently model the high‐latitude ionospheric equivalent current. Using a 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 magnetometers, we focus on the model output along the 105° magnetic meridian. Our improvements involve fixed data locations and SECS analysis grid and using a priori knowledge of the large‐scale currents improving the robustness of the inverse problem solution. We account for contributions from ground induced currents assuming so‐called mirror currents. This study produces a new data set of divergence‐free (DF) currents and magnetic field perturbations along the 105° magnetic meridian with 1‐min resolution. By comparing averages of the data set with an empirical model of the ionosphere we demonstrate the validity of the data set. We show how our data set, in particular its temporal nature, is distinct from empirical models and other studies. Not only can the temporal evolution of the DF currents and magnetic field perturbations be investigated, but the time derivative of said quantities can be analyzed. For application in ground induced currents, we present the statistical properties of where (in magnetic latitude and local time) and at what rate (∂Br/∂t) the radial magnetic field component fluctuates, a temporal derivative that has received very little attention. We show that ∂Br/∂t is dependent on latitude, local time, and solar cycle. We present other applications such as Ultra Low Frequency Waves monitoring.https://doi.org/10.1029/2022SW003305spherical elementary currentsauroral electrojetsground induced currentsground magnetometersderivative of the radial magnetic fieldultra low frequency waves |
| spellingShingle | Simon Walker Karl Laundal Jone Reistad Anders Ohma Spencer Hatch Statistical Temporal Variations in the Auroral Electrojet Estimated With Ground Magnetometers in Fennoscandia Space Weather spherical elementary currents auroral electrojets ground induced currents ground magnetometers derivative of the radial magnetic field ultra low frequency waves |
| title | Statistical Temporal Variations in the Auroral Electrojet Estimated With Ground Magnetometers in Fennoscandia |
| title_full | Statistical Temporal Variations in the Auroral Electrojet Estimated With Ground Magnetometers in Fennoscandia |
| title_fullStr | Statistical Temporal Variations in the Auroral Electrojet Estimated With Ground Magnetometers in Fennoscandia |
| title_full_unstemmed | Statistical Temporal Variations in the Auroral Electrojet Estimated With Ground Magnetometers in Fennoscandia |
| title_short | Statistical Temporal Variations in the Auroral Electrojet Estimated With Ground Magnetometers in Fennoscandia |
| title_sort | statistical temporal variations in the auroral electrojet estimated with ground magnetometers in fennoscandia |
| topic | spherical elementary currents auroral electrojets ground induced currents ground magnetometers derivative of the radial magnetic field ultra low frequency waves |
| url | https://doi.org/10.1029/2022SW003305 |
| work_keys_str_mv | AT simonwalker statisticaltemporalvariationsintheauroralelectrojetestimatedwithgroundmagnetometersinfennoscandia AT karllaundal statisticaltemporalvariationsintheauroralelectrojetestimatedwithgroundmagnetometersinfennoscandia AT jonereistad statisticaltemporalvariationsintheauroralelectrojetestimatedwithgroundmagnetometersinfennoscandia AT andersohma statisticaltemporalvariationsintheauroralelectrojetestimatedwithgroundmagnetometersinfennoscandia AT spencerhatch statisticaltemporalvariationsintheauroralelectrojetestimatedwithgroundmagnetometersinfennoscandia |