Articles | Volume 42, issue 1
https://doi.org/10.5194/angeo-42-163-2024
© Author(s) 2024. 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-42-163-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Regular paper
| 
27 May 2024
Regular paper |
| 27 May 2024
| 27 May 2024
Permutation entropy and complexity analysis of large-scale solar wind structures and streams
Emilia K. J. Kilpua
CORRESPONDING AUTHOR
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
Matti Ala-Lahti
Department of Climate and Space Sciences and Engineering, University of Michigan, 2455 Hayward St., Ann Arbor, MI 48109-2143, USA
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
Venla Koikkalainen
Department of Physics, University of Helsinki, P.O. Box 64, 00014 Helsinki, Finland
Related authors
Venla Koikkalainen, Emilia Kilpua, Simon Good, and Adnane Osmane
Nonlin. Processes Geophys., 32, 309–327, https://doi.org/10.5194/npg-32-309-2025, https://doi.org/10.5194/npg-32-309-2025, 2025
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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.
Emilia Kilpua, Simon Good, Juska Soljento, Domenico Trotta, Tia Bäcker, Julia Ruohotie, Jens Pomoell, Chaitanya Sishtla, and Rami Vainio
Ann. Geophys., 43, 489–510, https://doi.org/10.5194/angeo-43-489-2025, https://doi.org/10.5194/angeo-43-489-2025, 2025
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Interplanetary shock waves are one of the major forms of heliospheric transients that can have a profound impact on solar wind plasma and magnetic field conditions and accelerate charged particles to high energies. This work performs an extensive statistical analysis to detail how some of the key solar wind turbulence parameters, critical for understanding particle acceleration, are modified by the interplanetary shocks waves.
Venla Koikkalainen, Maxime Grandin, Emilia Kilpua, Abiyot Workayehu, Ivan Zaitsev, Liisa Juusola, Shi Tao, Markku Alho, Lauri Pänkäläinen, Giulia Cozzani, Konstantinos Horaites, Jonas Suni, Yann Pfau-Kempf, Urs Ganse, and Minna Palmroth
EGUsphere, https://doi.org/10.5194/egusphere-2025-2265, https://doi.org/10.5194/egusphere-2025-2265, 2025
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We use a numerical simulation to study phenomena that occur between the Earth’s dipolar magnetic field and the nightside of near-Earth space. We observe the formation of large-scale vortex flows with scales of several Earth radii. On the ionospheric grid of the simulation we find that the field-aligned currents formed in the simulation reflect the vortex flow in the transition region. The main finding is that the vortex flow is a result of a combination of flow dynamics and a plasma instability.
Sanni Hoilijoki, Emilia Kilpua, Adnane Osmane, Lucile Turc, Mikko Savola, Veera Lipsanen, Harriet George, and Milla Kalliokoski
Ann. Geophys. Discuss., https://doi.org/10.5194/angeo-2024-3, https://doi.org/10.5194/angeo-2024-3, 2024
Preprint under review for ANGEO
Short summary
Short summary
Structures originating from the Sun, such as coronal mass ejections and high-speed streams, may impact the Earth's magnetosphere differently. The occurrence rate of these structures depends on the phase solar cycle. We use mutual information to study the change in the statistical dependence between solar wind and inner magnetosphere. We find that the non-linearity between solar wind and inner magnetosphere varies over the solar cycle and during different solar wind drivers.
Adnane Osmane, Mikko Savola, Emilia Kilpua, Hannu Koskinen, Joseph E. Borovsky, and Milla Kalliokoski
Ann. Geophys., 40, 37–53, https://doi.org/10.5194/angeo-40-37-2022, https://doi.org/10.5194/angeo-40-37-2022, 2022
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It has long been known that particles get accelerated close to the speed of light in the near-Earth space environment. Research in the last decades has also clarified what processes and waves are responsible for the acceleration of particles. However, it is difficult to quantify the scale of the impact of various processes competing with one another. In this study we present a methodology to quantify the impact waves can have on energetic particles.
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
Ann. Geophys., 39, 1013–1035, https://doi.org/10.5194/angeo-39-1013-2021, https://doi.org/10.5194/angeo-39-1013-2021, 2021
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We present a detailed account of the science programme PRESTO (PREdictability of the variable Solar–Terrestrial cOupling), covering the period 2020 to 2024. PRESTO was defined by a dedicated committee established by SCOSTEP (Scientific Committee on Solar-Terrestrial Physics). We review the current state of the art and discuss future studies required for the most effective development of solar–terrestrial physics.
Andrei Runov, Maxime Grandin, Minna Palmroth, Markus Battarbee, Urs Ganse, Heli Hietala, Sanni Hoilijoki, Emilia Kilpua, Yann Pfau-Kempf, Sergio Toledo-Redondo, Lucile Turc, and Drew Turner
Ann. Geophys., 39, 599–612, https://doi.org/10.5194/angeo-39-599-2021, https://doi.org/10.5194/angeo-39-599-2021, 2021
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In collisionless systems like space plasma, particle velocity distributions contain fingerprints of ongoing physical processes. However, it is challenging to decode this information from observations. We used hybrid-Vlasov simulations to obtain ion velocity distribution functions at different locations and at different stages of the Earth's magnetosphere dynamics. The obtained distributions provide valuable examples that may be directly compared with observations by satellites in space.
Emilia K. J. Kilpua, Dominique Fontaine, Simon W. Good, Matti Ala-Lahti, Adnane Osmane, Erika Palmerio, Emiliya Yordanova, Clement Moissard, Lina Z. Hadid, and Miho Janvier
Ann. Geophys., 38, 999–1017, https://doi.org/10.5194/angeo-38-999-2020, https://doi.org/10.5194/angeo-38-999-2020, 2020
Short summary
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This paper studies magnetic field fluctuations in three turbulent sheath regions ahead of interplanetary coronal mass ejections (ICMEs) in the near-Earth solar wind. Our results show that fluctuation properties vary significantly in different parts of the sheath when compared to solar wind ahead. Turbulence in sheaths resembles that of the slow solar wind in the terrestrial magnetosheath, e.g. regarding compressibility and intermittency, and it often lacks Kolmogorov's spectral indices.
Venla Koikkalainen, Emilia Kilpua, Simon Good, and Adnane Osmane
Nonlin. Processes Geophys., 32, 309–327, https://doi.org/10.5194/npg-32-309-2025, https://doi.org/10.5194/npg-32-309-2025, 2025
Short summary
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.
Emilia Kilpua, Simon Good, Juska Soljento, Domenico Trotta, Tia Bäcker, Julia Ruohotie, Jens Pomoell, Chaitanya Sishtla, and Rami Vainio
Ann. Geophys., 43, 489–510, https://doi.org/10.5194/angeo-43-489-2025, https://doi.org/10.5194/angeo-43-489-2025, 2025
Short summary
Short summary
Interplanetary shock waves are one of the major forms of heliospheric transients that can have a profound impact on solar wind plasma and magnetic field conditions and accelerate charged particles to high energies. This work performs an extensive statistical analysis to detail how some of the key solar wind turbulence parameters, critical for understanding particle acceleration, are modified by the interplanetary shocks waves.
Abiyot Bires Workayehu, Minna Palmroth, Maxime Grandin, Liisa Juusola, Markku Alho, Ivan Zaitsev, Venla Koikkalainen, Konstantinos Horaites, Yann Pfau-Kempf, Urs Ganse, Markus Battarbee, and Jonas Suni
EGUsphere, https://doi.org/10.5194/egusphere-2025-2282, https://doi.org/10.5194/egusphere-2025-2282, 2025
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We investigate the ionospheric signatures of BBFs in the magnetotail utilising a global 6D hybrid-Vlasov simulation coupled with an ionospheric model. We analyse changes in the magnitudes of ionospheric observables and use them as the ionospheric manifestations of bursty bulk flows. Our results reveal that reconnection-driven BBF induce vortices that generate FACs, which map to the ionosphere with distinct east-west alignment and exhibit a characteristic westward drift.
Venla Koikkalainen, Maxime Grandin, Emilia Kilpua, Abiyot Workayehu, Ivan Zaitsev, Liisa Juusola, Shi Tao, Markku Alho, Lauri Pänkäläinen, Giulia Cozzani, Konstantinos Horaites, Jonas Suni, Yann Pfau-Kempf, Urs Ganse, and Minna Palmroth
EGUsphere, https://doi.org/10.5194/egusphere-2025-2265, https://doi.org/10.5194/egusphere-2025-2265, 2025
Short summary
Short summary
We use a numerical simulation to study phenomena that occur between the Earth’s dipolar magnetic field and the nightside of near-Earth space. We observe the formation of large-scale vortex flows with scales of several Earth radii. On the ionospheric grid of the simulation we find that the field-aligned currents formed in the simulation reflect the vortex flow in the transition region. The main finding is that the vortex flow is a result of a combination of flow dynamics and a plasma instability.
Anton Fetzer, Mikko Savola, Adnane Osmane, Vili-Arttu Ketola, Philipp Oleynik, and Minna Palmroth
EGUsphere, https://doi.org/10.5194/egusphere-2025-1279, https://doi.org/10.5194/egusphere-2025-1279, 2025
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Extreme events can pose serious risks to satellites, potentially disrupting communication, navigation, and power systems. Our study estimates the worst-case radiation levels during such an event and assesses their impact on electronics and solar panels.
Sanni Hoilijoki, Emilia Kilpua, Adnane Osmane, Lucile Turc, Mikko Savola, Veera Lipsanen, Harriet George, and Milla Kalliokoski
Ann. Geophys. Discuss., https://doi.org/10.5194/angeo-2024-3, https://doi.org/10.5194/angeo-2024-3, 2024
Preprint under review for ANGEO
Short summary
Short summary
Structures originating from the Sun, such as coronal mass ejections and high-speed streams, may impact the Earth's magnetosphere differently. The occurrence rate of these structures depends on the phase solar cycle. We use mutual information to study the change in the statistical dependence between solar wind and inner magnetosphere. We find that the non-linearity between solar wind and inner magnetosphere varies over the solar cycle and during different solar wind drivers.
Adnane Osmane, Mikko Savola, Emilia Kilpua, Hannu Koskinen, Joseph E. Borovsky, and Milla Kalliokoski
Ann. Geophys., 40, 37–53, https://doi.org/10.5194/angeo-40-37-2022, https://doi.org/10.5194/angeo-40-37-2022, 2022
Short summary
Short summary
It has long been known that particles get accelerated close to the speed of light in the near-Earth space environment. Research in the last decades has also clarified what processes and waves are responsible for the acceleration of particles. However, it is difficult to quantify the scale of the impact of various processes competing with one another. In this study we present a methodology to quantify the impact waves can have on energetic particles.
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
Ann. Geophys., 39, 1013–1035, https://doi.org/10.5194/angeo-39-1013-2021, https://doi.org/10.5194/angeo-39-1013-2021, 2021
Short summary
Short summary
We present a detailed account of the science programme PRESTO (PREdictability of the variable Solar–Terrestrial cOupling), covering the period 2020 to 2024. PRESTO was defined by a dedicated committee established by SCOSTEP (Scientific Committee on Solar-Terrestrial Physics). We review the current state of the art and discuss future studies required for the most effective development of solar–terrestrial physics.
Andrei Runov, Maxime Grandin, Minna Palmroth, Markus Battarbee, Urs Ganse, Heli Hietala, Sanni Hoilijoki, Emilia Kilpua, Yann Pfau-Kempf, Sergio Toledo-Redondo, Lucile Turc, and Drew Turner
Ann. Geophys., 39, 599–612, https://doi.org/10.5194/angeo-39-599-2021, https://doi.org/10.5194/angeo-39-599-2021, 2021
Short summary
Short summary
In collisionless systems like space plasma, particle velocity distributions contain fingerprints of ongoing physical processes. However, it is challenging to decode this information from observations. We used hybrid-Vlasov simulations to obtain ion velocity distribution functions at different locations and at different stages of the Earth's magnetosphere dynamics. The obtained distributions provide valuable examples that may be directly compared with observations by satellites in space.
Minna Palmroth, Savvas Raptis, Jonas Suni, Tomas Karlsson, Lucile Turc, Andreas Johlander, Urs Ganse, Yann Pfau-Kempf, Xochitl Blanco-Cano, Mojtaba Akhavan-Tafti, Markus Battarbee, Maxime Dubart, Maxime Grandin, Vertti Tarvus, and Adnane Osmane
Ann. Geophys., 39, 289–308, https://doi.org/10.5194/angeo-39-289-2021, https://doi.org/10.5194/angeo-39-289-2021, 2021
Short summary
Short summary
Magnetosheath jets are high-velocity features within the Earth's turbulent magnetosheath, separating the Earth's magnetic domain from the solar wind. The characteristics of the jets are difficult to assess statistically as a function of their lifetime because normally spacecraft observe them only at one position within the magnetosheath. This study first confirms the accuracy of the model used, Vlasiator, by comparing it to MMS spacecraft, and then carries out the first jet lifetime statistics.
Maxime Dubart, Urs Ganse, Adnane Osmane, Andreas Johlander, Markus Battarbee, Maxime Grandin, Yann Pfau-Kempf, Lucile Turc, and Minna Palmroth
Ann. Geophys., 38, 1283–1298, https://doi.org/10.5194/angeo-38-1283-2020, https://doi.org/10.5194/angeo-38-1283-2020, 2020
Short summary
Short summary
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.
Emilia K. J. Kilpua, Dominique Fontaine, Simon W. Good, Matti Ala-Lahti, Adnane Osmane, Erika Palmerio, Emiliya Yordanova, Clement Moissard, Lina Z. Hadid, and Miho Janvier
Ann. Geophys., 38, 999–1017, https://doi.org/10.5194/angeo-38-999-2020, https://doi.org/10.5194/angeo-38-999-2020, 2020
Short summary
Short summary
This paper studies magnetic field fluctuations in three turbulent sheath regions ahead of interplanetary coronal mass ejections (ICMEs) in the near-Earth solar wind. Our results show that fluctuation properties vary significantly in different parts of the sheath when compared to solar wind ahead. Turbulence in sheaths resembles that of the slow solar wind in the terrestrial magnetosheath, e.g. regarding compressibility and intermittency, and it often lacks Kolmogorov's spectral indices.
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Short summary
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.
The solar wind is organised into slow and fast streams, interaction regions, and transient...
