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Although global magnetohydrodynamic (MHD) models have increased in sophistication and are now at the forefront of modeling Space Weather, there is still no clear understanding of how well these models replicate the observed ionospheric current systems. Without a full understanding and treatment of the ionospheric current systems, global models will have significant shortcomings that will limit their use. In this study we focus on reproducing observed seasonal interhemispheric asymmetry in ionospheric currents using the Space Weather Modeling Framework (SWMF). We find that SWMF does reproduce the linear relationship between the electrojets and the FACs, despite the underestimation of the currents’ magnitudes. Quantitatively, we find that at best SWMF is only capturing approximately 60% of the observed current. We also investigate how varying F10.7 effects the ionospheric potential and currents during the summer and winter. We find that simulations ran with higher F10.7 result in lower ionospheric potentials. Additionally, we find that the models do not always replicate the expected behavior of the currents with varying F10.7. This work points to a needed improvement in ionospheric conductance models.
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The effect of F10.7 on interhemispheric differences in ionospheric current during solstices
We investigate the differences in the electrojet and Birkeland current systems during summer and winter solstice and the effect of F10.7. The difference in solar illumination of the polar ionosphere during the winter versus summer solstice results in significantly higher conductivity in the summer polar ionosphere. As expected, the currents are larger during the summer than during the winter. The rela- tionship between the electrojets and the Birkeland current systems is essentially constant across seasons, as expected if the ionospheric electrojets close the Birkeland currents. The magnitude of F10.7 is an indicator of the level of solar-generated ionospheric conductance, therefore, one would expect larger ionospheric currents during periods of larger F10.7. This holds true for the summer solstice periods, however, the opposite trend is observed during the winter solstice periods. We provide an explanation for this finding based on the con- trol of the dayside merging rate by the magnetosheath flow pattern.
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- PAR ID:
- 10333074
- Date Published:
- Journal Name:
- Advances in space research
- ISSN:
- 0273-1177
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1016/j.asr.2022.02.006
