Articles | Volume 32, issue 3
https://doi.org/10.5194/npg-32-309-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/npg-32-309-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
10 Sep 2025
Research article |
| 10 Sep 2025
| 10 Sep 2025
Exploring complexity measures for analysis of solar wind structures and streams
Venla Koikkalainen
CORRESPONDING AUTHOR
Department of Physics, University of Helsinki, P.O. Box 64, 00014 Helsinki, Finland
Emilia Kilpua
Department of Physics, University of Helsinki, P.O. Box 64, 00014 Helsinki, Finland
Simon Good
Department of Physics, University of Helsinki, P.O. Box 64, 00014 Helsinki, Finland
Adnane Osmane
Department of Physics, University of Helsinki, P.O. Box 64, 00014 Helsinki, Finland
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The solar wind is organised into slow and fast streams, interaction regions, and transient structures originating from solar eruptions. Their internal characteristics are not well understood. A more comprehensive understanding of such features can give insight itno physical processes governing their formation and evolution. Using tools from information theory, we find that the solar wind shows universal turbulent properties on smaller scales, while on larger scales, clear differences arise.
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This study investigates the ionospheric signatures of a Bursty Bulk Flow in Earth’s magnetotail using a global 6D hybrid-Vlasov simulation coupled with an ionospheric model. The results show that a reconnection-driven Bursty Bulk Flow generates vortices that produce field-aligned currents, which map to the ionosphere with a distinct east–west orientation and exhibit a characteristic westward drift. Variations in ionospheric observables are identified as clear signatures of this flow.
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Ioannis A. Daglis, Loren C. Chang, Sergio Dasso, Nat Gopalswamy, Olga V. Khabarova, Emilia Kilpua, Ramon Lopez, Daniel Marsh, Katja Matthes, Dibyendu Nandy, Annika Seppälä, Kazuo Shiokawa, Rémi Thiéblemont, and Qiugang Zong
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Plasma waves are ubiquitous in the Earth's magnetosphere. They are responsible for many energetic processes happening in Earth's atmosphere, such as auroras. In order to understand these processes, thorough investigations of these waves are needed. We use a state-of-the-art numerical model to do so. Here we investigate the impact of different spatial resolutions in the model on these waves in order to improve in the future the model without wasting computational resources.
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Short summary
We study time series of solar wind large-scale structures (magnetic clouds, sheaths, slow and fast streams). These have profound importance with regard to causing disturbances in the heliospheric conditions and driving space weather on Earth. The used techniques include methods derived from information theory to determine entropy and complexity. We find that all of these techniques show stochastic fluctuations, but magnetic clouds stand out due to their coherent magnetic field.
We study time series of solar wind large-scale structures (magnetic clouds, sheaths, slow and...
