Articles | Volume 39, issue 5
https://doi.org/10.5194/angeo-39-911-2021
© Author(s) 2021. 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-39-911-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Regular paper
| 
14 Oct 2021
Regular paper |
| 14 Oct 2021
| 14 Oct 2021
Foreshock cavitons and spontaneous hot flow anomalies: a statistical study with a global hybrid-Vlasov simulation
Department of Physics, University of Helsinki, Helsinki, Finland
Lucile Turc
Department of Physics, University of Helsinki, Helsinki, Finland
Markus Battarbee
Department of Physics, University of Helsinki, Helsinki, Finland
Jonas Suni
Department of Physics, University of Helsinki, Helsinki, Finland
Xóchitl Blanco-Cano
Instituto de Geofísica, Universidad Nacional Autónoma de México, Mexico City, Mexico
Urs Ganse
Department of Physics, University of Helsinki, Helsinki, Finland
Yann Pfau-Kempf
Department of Physics, University of Helsinki, Helsinki, Finland
Markku Alho
Department of Physics, University of Helsinki, Helsinki, Finland
Maxime Dubart
Department of Physics, University of Helsinki, Helsinki, Finland
Maxime Grandin
Department of Physics, University of Helsinki, Helsinki, Finland
Andreas Johlander
Department of Physics, University of Helsinki, Helsinki, Finland
Konstantinos Papadakis
Department of Physics, University of Helsinki, Helsinki, Finland
Minna Palmroth
Department of Physics, University of Helsinki, Helsinki, Finland
Finnish Meteorological Institute, Helsinki, Finland
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Magnetic reconnection is one of the main processes for energy conversion and plasma transport in space plasma physics, associated with plasma entry into the magnetosphere of Earth and Earth’s substorm cycle. Global modelling of these plasma processes enables us to understand the magnetospheric system in detail. However, finding sites of active reconnection from large simulation datasets can be challenging, and this paper develops tools to find magnetic topologies related to reconnection.
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Magnetosheath jets are structures of enhanced plasma density and/or velocity in a region of near-Earth space known as the magnetosheath. When they propagate towards the Earth, these jets can disturb the Earth's magnetic field and cause hazards for satellites. In this study, we use a simulation called Vlasiator to model near-Earth space and investigate jets using case studies and statistical analysis. We find that jets that propagate towards the Earth are different from jets that do not.
Konstantinos Papadakis, Yann Pfau-Kempf, Urs Ganse, Markus Battarbee, Markku Alho, Maxime Grandin, Maxime Dubart, Lucile Turc, Hongyang Zhou, Konstantinos Horaites, Ivan Zaitsev, Giulia Cozzani, Maarja Bussov, Evgeny Gordeev, Fasil Tesema, Harriet George, Jonas Suni, Vertti Tarvus, and Minna Palmroth
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Vlasiator is a plasma simulation code that simulates the entire near-Earth space at a global scale. As 6D simulations require enormous amounts of computational resources, Vlasiator uses adaptive mesh refinement (AMR) to lighten the computational burden. However, due to Vlasiator’s grid topology, AMR simulations suffer from grid aliasing artifacts that affect the global results. In this work, we present and evaluate the performance of a mechanism for alleviating those artifacts.
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
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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.
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Using global computer simulations, we study properties of the magnetosheath, the region of near-Earth space where the stream of particles originating from the Sun, the solar wind, is slowed down and deflected around the Earth's magnetic field. One of our main findings is that even for idealised solar wind conditions as used in our model, the magnetosheath density shows large-scale spatial and temporal variation in the so-called quasi-parallel magnetosheath, causing varying levels of asymmetry.
Yann Pfau-Kempf, Konstantinos Papadakis, Markku Alho, Markus Battarbee, Giulia Cozzani, Lauri Pänkäläinen, Urs Ganse, Fasil Kebede, Jonas Suni, Konstantinos Horaites, Maxime Grandin, and Minna Palmroth
Ann. Geophys. Discuss., https://doi.org/10.5194/angeo-2024-26, https://doi.org/10.5194/angeo-2024-26, 2024
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Noora Partamies, Rowan Dayton-Oxland, Katie Herlingshaw, Ilkka Virtanen, Bea Gallardo-Lacourt, Mikko Syrjäsuo, Fred Sigernes, Takanori Nishiyama, Toshi Nishimura, Mathieu Barthelemy, Anasuya Aruliah, Daniel Whiter, Lena Mielke, Maxime Grandin, Eero Karvinen, Marjan Spijkers, and Vincent Ledvina
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We studied the first broad band emissions, called continuum, in the dayside aurora. They are similar to STEVE with white, pale pink or mauve coloured light. But unlike STEVE, they follow the dayside aurora forming rays and other dynamic shapes. We used ground optical and radar observations and found evidence of heating and upwelling of both plasma and neutral air. This study provides new information on conditions for continuum emission, but its understanding will require further work.
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Auroral displays typically take place at high latitudes, but the exact latitude where the auroral breakup occurs can vary. In this study, we compare the characteristics of the fluxes of precipitating electrons from space during auroral breakups occurring above Tromsø (central part of the auroral zone) and above Svalbard (poleward boundary of the auroral zone). We find that electrons responsible for the aurora above Tromsø carry more energy than those precipitating above Svalbard.
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Urs Ganse, Yann Pfau-Kempf, Hongyang Zhou, Liisa Juusola, Abiyot Workayehu, Fasil Kebede, Konstantinos Papadakis, Maxime Grandin, Markku Alho, Markus Battarbee, Maxime Dubart, Leo Kotipalo, Arnaud Lalagüe, Jonas Suni, Konstantinos Horaites, and Minna Palmroth
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Vlasiator is a kinetic space-plasma model that simulates the behaviour of plasma, solar wind and magnetic fields in near-Earth space. So far, these simulations had been run without any interaction wtih the ionosphere, the uppermost layer of Earth's atmosphere. In this manuscript, we present the new methods that add an ionospheric electrodynamics model to Vlasiator, coupling it with the existing methods and presenting new simulation results of how space Plasma and Earth's ionosphere interact.
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Ann. Geophys. Discuss., https://doi.org/10.5194/angeo-2024-7, https://doi.org/10.5194/angeo-2024-7, 2024
Revised manuscript under review for ANGEO
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We study the atmospheric impact of auroral electron precipitation, by the novel combination of both magnetospheric and atmospheric modelling. We first simulate fluxes of auroral electrons, and then use these fluxes to model their atmospheric impact. We find an increase of up to 200 % in thermospheric odd nitrogen, and a corresponding decrease in stratospheric ozone of around 0.7 %. The produced auroral electron precipitation is realistic, and shows the potential for future studies.
Markku Alho, Giulia Cozzani, Ivan Zaitsev, Fasil Tesema Kebede, Urs Ganse, Markus Battarbee, Maarja Bussov, Maxime Dubart, Sanni Hoilijoki, Leo Kotipalo, Konstantinos Papadakis, Yann Pfau-Kempf, Jonas Suni, Vertti Tarvus, Abiyot Workayehu, Hongyang Zhou, and Minna Palmroth
Ann. Geophys., 42, 145–161, https://doi.org/10.5194/angeo-42-145-2024, https://doi.org/10.5194/angeo-42-145-2024, 2024
Short summary
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Magnetic reconnection is one of the main processes for energy conversion and plasma transport in space plasma physics, associated with plasma entry into the magnetosphere of Earth and Earth’s substorm cycle. Global modelling of these plasma processes enables us to understand the magnetospheric system in detail. However, finding sites of active reconnection from large simulation datasets can be challenging, and this paper develops tools to find magnetic topologies related to reconnection.
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
Revised manuscript under review for ANGEO
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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.
Jonas Suni, Minna Palmroth, Lucile Turc, Markus Battarbee, Giulia Cozzani, Maxime Dubart, Urs Ganse, Harriet George, Evgeny Gordeev, Konstantinos Papadakis, Yann Pfau-Kempf, Vertti Tarvus, Fasil Tesema, and Hongyang Zhou
Ann. Geophys., 41, 551–568, https://doi.org/10.5194/angeo-41-551-2023, https://doi.org/10.5194/angeo-41-551-2023, 2023
Short summary
Short summary
Magnetosheath jets are structures of enhanced plasma density and/or velocity in a region of near-Earth space known as the magnetosheath. When they propagate towards the Earth, these jets can disturb the Earth's magnetic field and cause hazards for satellites. In this study, we use a simulation called Vlasiator to model near-Earth space and investigate jets using case studies and statistical analysis. We find that jets that propagate towards the Earth are different from jets that do not.
Konstantinos Papadakis, Yann Pfau-Kempf, Urs Ganse, Markus Battarbee, Markku Alho, Maxime Grandin, Maxime Dubart, Lucile Turc, Hongyang Zhou, Konstantinos Horaites, Ivan Zaitsev, Giulia Cozzani, Maarja Bussov, Evgeny Gordeev, Fasil Tesema, Harriet George, Jonas Suni, Vertti Tarvus, and Minna Palmroth
Geosci. Model Dev., 15, 7903–7912, https://doi.org/10.5194/gmd-15-7903-2022, https://doi.org/10.5194/gmd-15-7903-2022, 2022
Short summary
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Vlasiator is a plasma simulation code that simulates the entire near-Earth space at a global scale. As 6D simulations require enormous amounts of computational resources, Vlasiator uses adaptive mesh refinement (AMR) to lighten the computational burden. However, due to Vlasiator’s grid topology, AMR simulations suffer from grid aliasing artifacts that affect the global results. In this work, we present and evaluate the performance of a mechanism for alleviating those artifacts.
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.
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.
Minna Palmroth, Maxime Grandin, Theodoros Sarris, Eelco Doornbos, Stelios Tourgaidis, Anita Aikio, Stephan Buchert, Mark A. Clilverd, Iannis Dandouras, Roderick Heelis, Alex Hoffmann, Nickolay Ivchenko, Guram Kervalishvili, David J. Knudsen, Anna Kotova, Han-Li Liu, David M. Malaspina, Günther March, Aurélie Marchaudon, Octav Marghitu, Tomoko Matsuo, Wojciech J. Miloch, Therese Moretto-Jørgensen, Dimitris Mpaloukidis, Nils Olsen, Konstantinos Papadakis, Robert Pfaff, Panagiotis Pirnaris, Christian Siemes, Claudia Stolle, Jonas Suni, Jose van den IJssel, Pekka T. Verronen, Pieter Visser, and Masatoshi Yamauchi
Ann. Geophys., 39, 189–237, https://doi.org/10.5194/angeo-39-189-2021, https://doi.org/10.5194/angeo-39-189-2021, 2021
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This is a review paper that summarises the current understanding of the lower thermosphere–ionosphere (LTI) in terms of measurements and modelling. The LTI is the transition region between space and the atmosphere and as such of tremendous importance to both the domains of space and atmosphere. The paper also serves as the background for European Space Agency Earth Explorer 10 candidate mission Daedalus.
Markus Battarbee, Thiago Brito, Markku Alho, Yann Pfau-Kempf, Maxime Grandin, Urs Ganse, Konstantinos Papadakis, Andreas Johlander, Lucile Turc, Maxime Dubart, and Minna Palmroth
Ann. Geophys., 39, 85–103, https://doi.org/10.5194/angeo-39-85-2021, https://doi.org/10.5194/angeo-39-85-2021, 2021
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We investigate local acceleration dynamics of electrons with a new numerical simulation method, which is an extension of a world-leading kinetic plasma simulation. We describe how large supercomputer simulations can be used to initialize the electron simulations and show numerical stability for the electron method. We show that features of our simulated electrons match observations from Earth's magnetic tail region.
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
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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.
Markus Battarbee, Xóchitl Blanco-Cano, Lucile Turc, Primož Kajdič, Andreas Johlander, Vertti Tarvus, Stephen Fuselier, Karlheinz Trattner, Markku Alho, Thiago Brito, Urs Ganse, Yann Pfau-Kempf, Mojtaba Akhavan-Tafti, Tomas Karlsson, Savvas Raptis, Maxime Dubart, Maxime Grandin, Jonas Suni, and Minna Palmroth
Ann. Geophys., 38, 1081–1099, https://doi.org/10.5194/angeo-38-1081-2020, https://doi.org/10.5194/angeo-38-1081-2020, 2020
Short summary
Short summary
We investigate the dynamics of helium in the foreshock, a part of near-Earth space found upstream of the Earth's bow shock. We show how the second most common ion in interplanetary space reacts strongly to plasma waves found in the foreshock. Spacecraft observations and supercomputer simulations both give us a new understanding of the foreshock edge and how to interpret future observations.
Lucile Turc, Vertti Tarvus, Andrew P. Dimmock, Markus Battarbee, Urs Ganse, Andreas Johlander, Maxime Grandin, Yann Pfau-Kempf, Maxime Dubart, and Minna Palmroth
Ann. Geophys., 38, 1045–1062, https://doi.org/10.5194/angeo-38-1045-2020, https://doi.org/10.5194/angeo-38-1045-2020, 2020
Short summary
Short summary
Using global computer simulations, we study properties of the magnetosheath, the region of near-Earth space where the stream of particles originating from the Sun, the solar wind, is slowed down and deflected around the Earth's magnetic field. One of our main findings is that even for idealised solar wind conditions as used in our model, the magnetosheath density shows large-scale spatial and temporal variation in the so-called quasi-parallel magnetosheath, causing varying levels of asymmetry.
Harriet George, Emilia Kilpua, Adnane Osmane, Timo Asikainen, Milla M. H. Kalliokoski, Craig J. Rodger, Stepan Dubyagin, and Minna Palmroth
Ann. Geophys., 38, 931–951, https://doi.org/10.5194/angeo-38-931-2020, https://doi.org/10.5194/angeo-38-931-2020, 2020
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We compared trapped outer radiation belt electron fluxes to high-latitude precipitating electron fluxes during two interplanetary coronal mass ejections (ICMEs) with opposite magnetic cloud rotation. The electron response had many similarities and differences between the two events, indicating that different acceleration mechanisms acted. Van Allen Probe data were used for trapped electron flux measurements, and Polar Operational Environmental Satellites were used for precipitating flux data.
Milla M. H. Kalliokoski, Emilia K. J. Kilpua, Adnane Osmane, Drew L. Turner, Allison N. Jaynes, Lucile Turc, Harriet George, and Minna Palmroth
Ann. Geophys., 38, 683–701, https://doi.org/10.5194/angeo-38-683-2020, https://doi.org/10.5194/angeo-38-683-2020, 2020
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We present a comprehensive statistical study of the response of the Earth's space environment in sheath regions prior to interplanetary coronal mass ejections. The inner magnetospheric wave activity is enhanced in sheath regions, and the sheaths cause significant changes to the outer radiation belt electron fluxes over short timescales. We also show that non-geoeffective sheaths can result in a significant response.
Markus Battarbee, Urs Ganse, Yann Pfau-Kempf, Lucile Turc, Thiago Brito, Maxime Grandin, Tuomas Koskela, and Minna Palmroth
Ann. Geophys., 38, 625–643, https://doi.org/10.5194/angeo-38-625-2020, https://doi.org/10.5194/angeo-38-625-2020, 2020
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The structure and medium-scale dynamics of Earth's bow shock and how charged solar wind particles are reflected by it are studied in order to better understand space weather effects. We use advanced supercomputer simulations to model the shock and reflected ions. We find that the thickness of the shock depends on solar wind conditions but also has small-scale variations. Charged particle reflection is shown to be non-localized. Magnetic fields are important for ion reflection.
Theodoros E. Sarris, Elsayed R. Talaat, Minna Palmroth, Iannis Dandouras, Errico Armandillo, Guram Kervalishvili, Stephan Buchert, Stylianos Tourgaidis, David M. Malaspina, Allison N. Jaynes, Nikolaos Paschalidis, John Sample, Jasper Halekas, Eelco Doornbos, Vaios Lappas, Therese Moretto Jørgensen, Claudia Stolle, Mark Clilverd, Qian Wu, Ingmar Sandberg, Panagiotis Pirnaris, and Anita Aikio
Geosci. Instrum. Method. Data Syst., 9, 153–191, https://doi.org/10.5194/gi-9-153-2020, https://doi.org/10.5194/gi-9-153-2020, 2020
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Daedalus aims to measure the largely unexplored area between Eart's atmosphere and space, the Earth's
ignorosphere. Here, intriguing and complex processes govern the deposition and transport of energy. The aim is to quantify this energy by measuring effects caused by electrodynamic processes in this region. The concept is based on a mother satellite that carries a suite of instruments, along with smaller satellites carrying a subset of instruments that are released into the atmosphere.
Emilia Kilpua, Liisa Juusola, Maxime Grandin, Antti Kero, Stepan Dubyagin, Noora Partamies, Adnane Osmane, Harriet George, Milla Kalliokoski, Tero Raita, Timo Asikainen, and Minna Palmroth
Ann. Geophys., 38, 557–574, https://doi.org/10.5194/angeo-38-557-2020, https://doi.org/10.5194/angeo-38-557-2020, 2020
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Coronal mass ejection sheaths and ejecta are key drivers of significant space weather storms, and they cause dramatic changes in radiation belt electron fluxes. Differences in precipitation of high-energy electrons from the belts to the upper atmosphere are thus expected. We investigate here differences in sheath- and ejecta-induced precipitation using the Finnish riometer (relative ionospheric opacity meter) chain.
Maxime Grandin, Markus Battarbee, Adnane Osmane, Urs Ganse, Yann Pfau-Kempf, Lucile Turc, Thiago Brito, Tuomas Koskela, Maxime Dubart, and Minna Palmroth
Ann. Geophys., 37, 791–806, https://doi.org/10.5194/angeo-37-791-2019, https://doi.org/10.5194/angeo-37-791-2019, 2019
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When the terrestrial magnetic field is disturbed, particles from the near-Earth space can precipitate into the upper atmosphere. This work presents, for the first time, numerical simulations of proton precipitation in the energy range associated with the production of aurora (∼1–30 keV) using a global kinetic model of the near-Earth space: Vlasiator. We find that nightside proton precipitation can be regulated by the transition region between stretched and dipolar geomagnetic field lines.
Antti Lakka, Tuija I. Pulkkinen, Andrew P. Dimmock, Emilia Kilpua, Matti Ala-Lahti, Ilja Honkonen, Minna Palmroth, and Osku Raukunen
Ann. Geophys., 37, 561–579, https://doi.org/10.5194/angeo-37-561-2019, https://doi.org/10.5194/angeo-37-561-2019, 2019
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We study how the Earth's space environment responds to two different amplitude interplanetary coronal mass ejection (ICME) events that occurred in 2012 and 2014 by using the GUMICS-4 global MHD model. We examine local and large-scale dynamics of the Earth's space environment and compare simulation results to in situ data. It is shown that during moderate driving simulation agrees well with the measurements; however, GMHD results should be interpreted cautiously during strong driving.
Liisa Juusola, Sanni Hoilijoki, Yann Pfau-Kempf, Urs Ganse, Riku Jarvinen, Markus Battarbee, Emilia Kilpua, Lucile Turc, and Minna Palmroth
Ann. Geophys., 36, 1183–1199, https://doi.org/10.5194/angeo-36-1183-2018, https://doi.org/10.5194/angeo-36-1183-2018, 2018
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The solar wind interacts with the Earth’s magnetic field, forming a magnetosphere. On the night side solar wind stretches the magnetosphere into a long tail. A process called magnetic reconnection opens the magnetic field lines and reconnects them, accelerating particles to high energies. We study this in the magnetotail using a numerical simulation model of the Earth’s magnetosphere. We study the motion of the points where field lines reconnect and the fast flows driven by this process.
Minna Palmroth, Heli Hietala, Ferdinand Plaschke, Martin Archer, Tomas Karlsson, Xóchitl Blanco-Cano, David Sibeck, Primož Kajdič, Urs Ganse, Yann Pfau-Kempf, Markus Battarbee, and Lucile Turc
Ann. Geophys., 36, 1171–1182, https://doi.org/10.5194/angeo-36-1171-2018, https://doi.org/10.5194/angeo-36-1171-2018, 2018
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Magnetosheath jets are high-velocity plasma structures that are commonly observed within the Earth's magnetosheath. Previously, they have mainly been investigated with spacecraft observations, which do not allow us to infer their spatial sizes, temporal evolution, or origin. This paper shows for the first time their dimensions, evolution, and origins within a simulation whose dimensions are directly comparable to the Earth's magnetosphere. The results are compared to previous observations.
Xochitl Blanco-Cano, Markus Battarbee, Lucile Turc, Andrew P. Dimmock, Emilia K. J. Kilpua, Sanni Hoilijoki, Urs Ganse, David G. Sibeck, Paul A. Cassak, Robert C. Fear, Riku Jarvinen, Liisa Juusola, Yann Pfau-Kempf, Rami Vainio, and Minna Palmroth
Ann. Geophys., 36, 1081–1097, https://doi.org/10.5194/angeo-36-1081-2018, https://doi.org/10.5194/angeo-36-1081-2018, 2018
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We use the Vlasiator code to study the characteristics of transient structures that exist in the Earth's foreshock, i.e. upstream of the bow shock. The structures are cavitons and spontaneous hot flow anomalies (SHFAs). These transients can interact with the bow shock. We study the changes the shock suffers via this interaction. We also investigate ion distributions associated with the cavitons and SHFAs. A very important result is that the arrival of multiple SHFAs results in shock erosion.
Liisa Juusola, Yann Pfau-Kempf, Urs Ganse, Markus Battarbee, Thiago Brito, Maxime Grandin, Lucile Turc, and Minna Palmroth
Ann. Geophys., 36, 1027–1035, https://doi.org/10.5194/angeo-36-1027-2018, https://doi.org/10.5194/angeo-36-1027-2018, 2018
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The Earth's magnetic field is shaped by the solar wind. On the dayside the field is compressed and on the nightside it is stretched as a long tail. The tail has been observed to occasionally undergo flapping motions, but the origin of these motions is not understood. We study the flapping using a numerical simulation of the near-Earth space. We present a possible explanation for how the flapping could be initiated by a passing disturbance and then maintained as a standing wave.
Minna Palmroth, Sanni Hoilijoki, Liisa Juusola, Tuija I. Pulkkinen, Heli Hietala, Yann Pfau-Kempf, Urs Ganse, Sebastian von Alfthan, Rami Vainio, and Michael Hesse
Ann. Geophys., 35, 1269–1274, https://doi.org/10.5194/angeo-35-1269-2017, https://doi.org/10.5194/angeo-35-1269-2017, 2017
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Much like solar flares, substorms occurring within the Earth's magnetic domain are explosive events that cause vivid auroral displays. A decades-long debate exists to explain the substorm onset. We devise a simulation encompassing the entire near-Earth space and demonstrate that detailed modelling of magnetic reconnection explains the central substorm observations. Our results help to understand the unpredictable substorm process, which will significantly improve space weather forecasts.
Antti Lakka, Tuija I. Pulkkinen, Andrew P. Dimmock, Adnane Osmane, Ilja Honkonen, Minna Palmroth, and Pekka Janhunen
Ann. Geophys., 35, 907–922, https://doi.org/10.5194/angeo-35-907-2017, https://doi.org/10.5194/angeo-35-907-2017, 2017
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We studied the impact on global MHD simulations from different simulation initialisation methods. While the global MHD code used is GUMICS-4 we conclude that the results might be generalisable to other codes as well. It is found that different initialisation methods affect the dynamics of the Earth's space environment by creating differences in momentum transport several hours afterwards. These differences may even grow as a response to rapid solar wind condition changes.
Yann Pfau-Kempf, Heli Hietala, Steve E. Milan, Liisa Juusola, Sanni Hoilijoki, Urs Ganse, Sebastian von Alfthan, and Minna Palmroth
Ann. Geophys., 34, 943–959, https://doi.org/10.5194/angeo-34-943-2016, https://doi.org/10.5194/angeo-34-943-2016, 2016
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We have simulated the interaction of the solar wind – the charged particles and magnetic fields emitted by the Sun into space – with the magnetic field of the Earth. The solar wind flows supersonically and creates a shock when it encounters the obstacle formed by the geomagnetic field. We have identified a new chain of events which causes phenomena in the downstream region to eventually cause perturbations at the shock and even upstream. This is confirmed by ground and satellite observations.
P. T. Verronen, M. E. Andersson, A. Kero, C.-F. Enell, J. M. Wissing, E. R. Talaat, K. Kauristie, M. Palmroth, T. E. Sarris, and E. Armandillo
Ann. Geophys., 33, 381–394, https://doi.org/10.5194/angeo-33-381-2015, https://doi.org/10.5194/angeo-33-381-2015, 2015
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Electron concentrations observed by EISCAT radars can be reasonable well represented using AIMOS v1.2 satellite-data-based ionization model and SIC D-region ion chemistry model. SIC-EISCAT difference varies from event to event, probably because the statistical nature of AIMOS ionization is not capturing all the spatio-temporal fine structure of electron precipitation. Below 90km, AIMOS overestimates electron ionization because of proton contamination of the satellite electron detectors.
L. Turc, D. Fontaine, P. Savoini, and E. K. J. Kilpua
Ann. Geophys., 32, 1247–1261, https://doi.org/10.5194/angeo-32-1247-2014, https://doi.org/10.5194/angeo-32-1247-2014, 2014
L. Turc, D. Fontaine, P. Savoini, and E. K. J. Kilpua
Ann. Geophys., 32, 157–173, https://doi.org/10.5194/angeo-32-157-2014, https://doi.org/10.5194/angeo-32-157-2014, 2014
D. Pokhotelov, S. von Alfthan, Y. Kempf, R. Vainio, H. E. J. Koskinen, and M. Palmroth
Ann. Geophys., 31, 2207–2212, https://doi.org/10.5194/angeo-31-2207-2013, https://doi.org/10.5194/angeo-31-2207-2013, 2013
P. Kajdič, X. Blanco-Cano, N. Omidi, K. Meziane, C. T. Russell, J.-A. Sauvaud, I. Dandouras, and B. Lavraud
Ann. Geophys., 31, 2163–2178, https://doi.org/10.5194/angeo-31-2163-2013, https://doi.org/10.5194/angeo-31-2163-2013, 2013
A. T. Aikio, T. Pitkänen, I. Honkonen, M. Palmroth, and O. Amm
Ann. Geophys., 31, 1021–1034, https://doi.org/10.5194/angeo-31-1021-2013, https://doi.org/10.5194/angeo-31-1021-2013, 2013
L. Turc, D. Fontaine, P. Savoini, H. Hietala, and E. K. J. Kilpua
Ann. Geophys., 31, 1011–1019, https://doi.org/10.5194/angeo-31-1011-2013, https://doi.org/10.5194/angeo-31-1011-2013, 2013
Related subject area
Subject: Magnetosphere & space plasma physics | Keywords: Bow shock and foreshock
Short large-amplitude magnetic structures (SLAMS) at Mercury observed by MESSENGER
Fine structure and motion of the bow shock and particle energisation mechanisms inferred from Magnetospheric Multiscale (MMS) observations
Evidence of the nonstationarity of the terrestrial bow shock from multi-spacecraft observations: methodology, results, and quantitative comparison with particle-in-cell (PIC) simulations
A deep insight into the ion foreshock with the help of test particle two-dimensional simulations
Helium in the Earth's foreshock: a global Vlasiator survey
Non-locality of Earth's quasi-parallel bow shock: injection of thermal protons in a hybrid-Vlasov simulation
Low-frequency magnetic variations at the high-β Earth bow shock
Comment on “Cavitons and spontaneous hot flow anomalies in a hybrid-Vlasov global magnetospheric simulation” by Blanco-Cano et al. (2018)
Reflection of the strahl within the foot of the Earth's bow shock
Cavitons and spontaneous hot flow anomalies in a hybrid-Vlasov global magnetospheric simulation
Tomas Karlsson, Ferdinand Plaschke, Austin N. Glass, and Jim M. Raines
Ann. Geophys., 42, 117–130, https://doi.org/10.5194/angeo-42-117-2024, https://doi.org/10.5194/angeo-42-117-2024, 2024
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The solar wind interacts with the planets in the solar system and creates a supersonic shock in front of them. The upstream region of this shock contains many complicated phenomena. One such phenomenon is small-scale structures of strong magnetic fields (SLAMS). These SLAMS have been observed at Earth and are important in determining the properties of space around the planet. Until now, SLAMS have not been observed at Mercury, but we show for the first time that SLAMS also exist there.
Krzysztof Stasiewicz and Zbigniew Kłos
Ann. Geophys., 40, 315–325, https://doi.org/10.5194/angeo-40-315-2022, https://doi.org/10.5194/angeo-40-315-2022, 2022
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The acceleration, or energisation, of particles is a common and fundamental process throughout the universe. This study presents new observations of the acceleration of protons by waves at the bow shock upstream of the Earth, where the solar wind first encounters Earth’s magnetic field. The results are important, because they provide insight into acceleration processes that can create high-energy particles both near the Earth and at other astrophysical systems.
Christian Mazelle and Bertrand Lembège
Ann. Geophys., 39, 571–598, https://doi.org/10.5194/angeo-39-571-2021, https://doi.org/10.5194/angeo-39-571-2021, 2021
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Nonstationarity of the quasi-perpendicular terrestrial bow shock is analyzed from magnetic field measurements, comparison with 2D particle-in-cell (PIC) simulations, and a careful and accurate methodology in the data processing. The results show evidence of a strong variability of the microstructures of the shock front (foot and ramp), confirming the importance of dissipative effects. These results indicate that these features can be signatures of the shock front self-reformation.
Philippe Savoini and Bertrand Lembège
Ann. Geophys., 38, 1217–1235, https://doi.org/10.5194/angeo-38-1217-2020, https://doi.org/10.5194/angeo-38-1217-2020, 2020
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Numerical simulations have been used to investigate some acceleration mechanisms in order to explain the origin of the energized back-streaming ions observed at the Earth's bow shock. This paper used test particles in two different configurations with self-consistent and fixed shock front profiles. The comparison of these two configurations allows us to analyze, in detail, the impact of the shock front nonstationarity and the role of the built-up electric field in the acceleration process.
Markus Battarbee, Xóchitl Blanco-Cano, Lucile Turc, Primož Kajdič, Andreas Johlander, Vertti Tarvus, Stephen Fuselier, Karlheinz Trattner, Markku Alho, Thiago Brito, Urs Ganse, Yann Pfau-Kempf, Mojtaba Akhavan-Tafti, Tomas Karlsson, Savvas Raptis, Maxime Dubart, Maxime Grandin, Jonas Suni, and Minna Palmroth
Ann. Geophys., 38, 1081–1099, https://doi.org/10.5194/angeo-38-1081-2020, https://doi.org/10.5194/angeo-38-1081-2020, 2020
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We investigate the dynamics of helium in the foreshock, a part of near-Earth space found upstream of the Earth's bow shock. We show how the second most common ion in interplanetary space reacts strongly to plasma waves found in the foreshock. Spacecraft observations and supercomputer simulations both give us a new understanding of the foreshock edge and how to interpret future observations.
Markus Battarbee, Urs Ganse, Yann Pfau-Kempf, Lucile Turc, Thiago Brito, Maxime Grandin, Tuomas Koskela, and Minna Palmroth
Ann. Geophys., 38, 625–643, https://doi.org/10.5194/angeo-38-625-2020, https://doi.org/10.5194/angeo-38-625-2020, 2020
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The structure and medium-scale dynamics of Earth's bow shock and how charged solar wind particles are reflected by it are studied in order to better understand space weather effects. We use advanced supercomputer simulations to model the shock and reflected ions. We find that the thickness of the shock depends on solar wind conditions but also has small-scale variations. Charged particle reflection is shown to be non-localized. Magnetic fields are important for ion reflection.
Anatoli A. Petrukovich, Olga M. Chugunova, and Pavel I. Shustov
Ann. Geophys., 37, 877–889, https://doi.org/10.5194/angeo-37-877-2019, https://doi.org/10.5194/angeo-37-877-2019, 2019
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Earth's bow shock in solar wind with high thermal and low magnetic pressure is a rare phenomenon. However, such an object is ubiquitous in astrophysical plasmas.
We surveyed statistics of such shock observations since 1995. About 100 crossings were initially identified. In this report 22 crossings from the Cluster project were studied using multipoint analysis, which allowed for the determination of the spatial scales of the shock transition and of the dominant magnetic variations
Gábor Facskó
Ann. Geophys., 37, 763–764, https://doi.org/10.5194/angeo-37-763-2019, https://doi.org/10.5194/angeo-37-763-2019, 2019
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Blanco-Cano et al. (2018) intended to find a type of transient event in the solar wind before the terrestrial bow shock using a special type of simulation. However, the simulation results cannot reproduce the main features of the event. Based on the remarks described below, I am sure that the features in the simulations are not those types of events. The Vlasiator code simulated proto-SHFAs.
Christopher A. Gurgiolo, Melvyn L. Goldstein, and Adolfo Viñas
Ann. Geophys., 37, 243–261, https://doi.org/10.5194/angeo-37-243-2019, https://doi.org/10.5194/angeo-37-243-2019, 2019
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The reflection of solar wind electrons at the bow shock helps define the physical properties of the foreshock, the region where the interplanetary magnetic field directly connects to the bow shock. We report that the strahl, the field-aligned component of the electron solar wind distribution, appears to be nearly fully reflected at the bow shock and that the reflection occurs in the foot of the shock, implying that mirroring is not the primary cause of the electron reflection.
Xochitl Blanco-Cano, Markus Battarbee, Lucile Turc, Andrew P. Dimmock, Emilia K. J. Kilpua, Sanni Hoilijoki, Urs Ganse, David G. Sibeck, Paul A. Cassak, Robert C. Fear, Riku Jarvinen, Liisa Juusola, Yann Pfau-Kempf, Rami Vainio, and Minna Palmroth
Ann. Geophys., 36, 1081–1097, https://doi.org/10.5194/angeo-36-1081-2018, https://doi.org/10.5194/angeo-36-1081-2018, 2018
Short summary
Short summary
We use the Vlasiator code to study the characteristics of transient structures that exist in the Earth's foreshock, i.e. upstream of the bow shock. The structures are cavitons and spontaneous hot flow anomalies (SHFAs). These transients can interact with the bow shock. We study the changes the shock suffers via this interaction. We also investigate ion distributions associated with the cavitons and SHFAs. A very important result is that the arrival of multiple SHFAs results in shock erosion.
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Short summary
We use simulations of Earth's magnetosphere and study the formation of transient wave structures in the region where the solar wind first interacts with the magnetosphere. These transients move earthward and play a part in the solar wind–magnetosphere interaction. We show that the transients are a common feature and their properties are altered as they move earthward, including an increase in temperature, decrease in solar wind speed and an alteration in their propagation properties.
We use simulations of Earth's magnetosphere and study the formation of transient wave structures...
