Articles | Volume 44, issue 1
https://doi.org/10.5194/angeo-44-405-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/angeo-44-405-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Regular paper
| 
29 May 2026
Regular paper |
| 29 May 2026
| 29 May 2026
New technique for isolating the auroral contribution in UV imagery: IMF By dependence of seasonal differences in auroral oval location during positive IMF Bz
Jens Christian Hessen
CORRESPONDING AUTHOR
Department of Physics and Technology, University of Bergen, Bergen, Norway
Jone Peter Reistad
OneSubsea Processing AS, Sandsli, Bergen, Norway
Spencer Mark Hatch
Department of Physics and Technology, University of Bergen, Bergen, Norway
Karl Magnus Laundal
Division of Geomagnetism and Geospace, DTU Space, Technical University of Denmark, Kongens Lyngby, Denmark
Yongliang Zhang
Applied Physics Laboratory, The Johns Hopkins University, Laurel, Maryland, USA
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Atmospheric winds at high altitudes (> 100 km) can play an important role in the electrodynamic processes that govern how ionospheric plasma interacts with Earth's neutral atmosphere. Here we investigate how a common idea in studies of ionospheric electrodynamics—that atmospheric winds can be ignored or represented via an average value—ignores the high variability of these winds. This variability forces a different formulation of the equations that govern ionosphere-thermosphere electrodynamics.
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Key properties of the ionospheric electrodynamics are electric fields, currents, and conductances. They provide a window to the vast and distant near-Earth space, cause Joule heating that affect satellite orbits, and drive geomagnetically induced currents (GICs) in technological conductor networks. We have developed a new method for solving the key properties of ionospheric electrodynamics from ground-based magnetic field observations.
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The EISCAT_3D radar is a new ionospheric radar under construction in the Fennoscandia region. The radar will make measurements of plasma characteristics at altitudes above approximately 60 km. The capability of the system to make these measurements at spatial scales of less than 100 m using multiple digitised signals from each of the radar antenna panels is highlighted. There are many ionospheric small-scale processes that will be further resolved using the techniques discussed here.
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In studies of the Earth's ionosphere, a hot topic is how to estimate ionospheric conductivity. This is hard to do for a variety of reasons that mostly amount to a lack of measurements. In this study we use satellite measurements to estimate electromagnetic work and ionospheric conductances in both hemispheres. We identify where our model estimates are inconsistent with laws of physics, which partially solves a previous problem with unrealistic predictions of ionospheric conductances.
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Short summary
Auroras, the natural lights seen in Earth's sky near the poles, are shaped by both Earth's and the solar wind's magnetic fields, as well as charged solar particles. This study examines how auroras change when the solar wind's magnetic field is dawn-dusk oriented. Daytime observations are challenging due to sunlight, so we developed a method to further separate auroras from background light. In summer, auroras shift east or west with/against the solar wind's magnetic field.
Auroras, the natural lights seen in Earth's sky near the poles, are shaped by both Earth's and...
