Articles | Volume 39, issue 1
https://doi.org/10.5194/angeo-39-189-2021
© 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-39-189-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Review paper
| 
25 Feb 2021
Review paper |
| 25 Feb 2021
| 25 Feb 2021
Lower-thermosphere–ionosphere (LTI) quantities: current status of measuring techniques and models
Minna Palmroth
CORRESPONDING AUTHOR
Department of Physics, University of Helsinki, Helsinki, Finland
Space and Earth Observation Centre, Finnish Meteorological Institute, Helsinki, Finland
Maxime Grandin
Department of Physics, University of Helsinki, Helsinki, Finland
Theodoros Sarris
Department of Electrical and Computer Engineering, Democritus University of Thrace, Xanthi, Greece
Eelco Doornbos
Royal Netherlands Meteorological Institute KNMI, Utrecht, the Netherlands
Stelios Tourgaidis
Department of Electrical and Computer Engineering, Democritus University of Thrace, Xanthi, Greece
Space Programmes Unit, Athena Research & Innovation Centre, Athens, Greece
Anita Aikio
Space Physics and Astronomy Research Unit, University of Oulu, Oulu, Finland
Stephan Buchert
Swedish Institute of Space Physics (IRF), Uppsala, Sweden
Mark A. Clilverd
British Antarctic Survey (UKRI-NERC), Cambridge, UK
Iannis Dandouras
Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, CNRS, CNES, Toulouse, France
Roderick Heelis
Center for Space Sciences, University of Texas at Dallas, Dallas, USA
Alex Hoffmann
European Space Research and Technology Centre, European Space Agency, Noordwijk, the Netherlands
Nickolay Ivchenko
Division of Space and Plasma Physics, Royal Institute of Technology KTH, Stockholm, Sweden
Guram Kervalishvili
GFZ Potsdam, German Research Centre for Geosciences, Potsdam, Germany
David J. Knudsen
Department of Physics and Astronomy, University of Calgary, Calgary, Canada
Anna Kotova
Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, CNRS, CNES, Toulouse, France
Han-Li Liu
National Center for Atmospheric Research, Boulder, USA
David M. Malaspina
Astrophysical and Planetary Sciences Department, University of Colorado, Boulder, USA
Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, USA
Günther March
Faculty of Aerospace Engineering, Delft University of Technology, Delft, the Netherlands
Aurélie Marchaudon
Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, CNRS, CNES, Toulouse, France
Octav Marghitu
Institute for Space Sciences, Bucharest, Romania
Tomoko Matsuo
Ann and H.J. Smead Department of Aerospace Engineering Sciences, University of Colorado at Boulder, Boulder, USA
Wojciech J. Miloch
Department of Physics, University of Oslo, Oslo, Norway
Therese Moretto-Jørgensen
University of Bergen, Institute of Physics and Technology, Bergen, Norway
Dimitris Mpaloukidis
Department of Electrical and Computer Engineering, Democritus University of Thrace, Xanthi, Greece
Nils Olsen
DTU Space, Technical University of Denmark, Copenhagen, Denmark
Konstantinos Papadakis
Department of Physics, University of Helsinki, Helsinki, Finland
Robert Pfaff
Heliophysics Science Division, NASA/Goddard Space Flight Center, Greenbelt, USA
Panagiotis Pirnaris
Department of Electrical and Computer Engineering, Democritus University of Thrace, Xanthi, Greece
Christian Siemes
Faculty of Aerospace Engineering, Delft University of Technology, Delft, the Netherlands
Claudia Stolle
GFZ Potsdam, German Research Centre for Geosciences, Potsdam, Germany
Faculty of Science, University of Potsdam, Potsdam, Germany
Jonas Suni
Department of Physics, University of Helsinki, Helsinki, Finland
Jose van den IJssel
Faculty of Aerospace Engineering, Delft University of Technology, Delft, the Netherlands
Pekka T. Verronen
Space and Earth Observation Centre, Finnish Meteorological Institute, Helsinki, Finland
Sodankylä Geophysical Observatory, University of Oulu, Sodankylä, Finland
Pieter Visser
Faculty of Aerospace Engineering, Delft University of Technology, Delft, the Netherlands
Masatoshi Yamauchi
Swedish Institute of Space Physics (IRF), Kiruna, Sweden
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Flux ropes are peculiar structures of twisted magnetic field occurring in many regions of space, near Earth and other planets, at the Sun, and in astrophysical objects. We developed a new way of detecting flux ropes in large supercomputer simulations of near-Earth space and we use it to follow the evolution of flux ropes for long distances past the Earth in the flow direction. This will be useful in future studies as these flux ropes are involved in the transport of matter and energy in space.
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This article is included in the Encyclopedia of Geosciences
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This article is included in the Encyclopedia of Geosciences
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This article is included in the Encyclopedia of Geosciences
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
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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.
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Vertti Tarvus, Lucile Turc, Markus Battarbee, Jonas Suni, Xóchitl Blanco-Cano, Urs Ganse, Yann Pfau-Kempf, Markku Alho, Maxime Dubart, Maxime Grandin, Andreas Johlander, Konstantinos Papadakis, and Minna Palmroth
Ann. Geophys., 39, 911–928, https://doi.org/10.5194/angeo-39-911-2021, https://doi.org/10.5194/angeo-39-911-2021, 2021
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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.
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
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
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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.
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
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
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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.
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
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
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
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.
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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.
This article is included in the Encyclopedia of Geosciences
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.
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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.
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
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
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
Karl M. Laundal, Andreas S. Skeidsvoll, Beatrice Popescu Braileanu, Spencer M. Hatch, Nils Olsen, and Heikki Vanhamäki
EGUsphere, https://doi.org/10.5194/egusphere-2025-2051, https://doi.org/10.5194/egusphere-2025-2051, 2025
This preprint is open for discussion and under review for Annales Geophysicae (ANGEO).
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The ionosphere is where Earth’s atmosphere overlaps with a gas of charged particles in space. There, collisions with neutral air and electromagnetic forces driven by the solar wind control plasma motion. We created a global model that includes magnetic induction, explaining how electric currents and fields are altered, offering a more accurate view of atmosphere–space coupling than conventional models based on electric circuits.
This article is included in the Encyclopedia of Geosciences
Markus Kunze, Christoph Zülicke, Tarique A. Siddiqui, Claudia C. Stephan, Yosuke Yamazaki, Claudia Stolle, Sebastian Borchert, and Hauke Schmidt
Geosci. Model Dev., 18, 3359–3385, https://doi.org/10.5194/gmd-18-3359-2025, https://doi.org/10.5194/gmd-18-3359-2025, 2025
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We present the Icosahedral Nonhydrostatic (ICON) general circulation model with an upper-atmospheric extension with the physics package for numerical weather prediction (UA-ICON(NWP)). We optimized the parameters for the gravity wave parameterizations and achieved realistic modeling of the thermal and dynamic states of the mesopause regions. UA-ICON(NWP) now shows a realistic frequency of major sudden stratospheric warmings and well-represented solar tides in temperature.
This article is included in the Encyclopedia of Geosciences
Sota Nanjo, Masatoshi Yamauchi, Magnar Gullikstad Johnsen, Yoshihiro Yokoyama, Urban Brändström, Yasunobu Ogawa, Anna Naemi Willer, and Keisuke Hosokawa
Ann. Geophys., 43, 303–317, https://doi.org/10.5194/angeo-43-303-2025, https://doi.org/10.5194/angeo-43-303-2025, 2025
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Our research explores the shock aurora, which is typically observed on the dayside due to the rapid compression of the Earth's magnetic field. We observed this rare aurora on the nightside, a region where such events are difficult to detect. Using ground-based cameras, we identified new features, including leaping and vortex-like patterns. These findings offer a fresh insight into the interactions between the solar wind and the magnetosphere, enhancing our understanding of space weather and its effects.
This article is included in the Encyclopedia of Geosciences
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
This preprint is open for discussion and under review for Annales Geophysicae (ANGEO).
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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.
This article is included in the Encyclopedia of Geosciences
Judit Pérez-Coll Jiménez, Nickolay Ivchenko, Ceona Lindstein, Lukas Krasauskas, Jonas Hedin, Donal Patrick Murtagh, Linda Megner, Björn Linder, and Jörg Gumbel
EGUsphere, https://doi.org/10.5194/egusphere-2025-2324, https://doi.org/10.5194/egusphere-2025-2324, 2025
This preprint is open for discussion and under review for Annales Geophysicae (ANGEO).
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This study uses images taken by the Swedish satellite MATS to conduct a statistical analysis of the molecular oxygen atmospheric band emissions in the aurora. This auroral emission can not be observed from the ground, making it one of the least understood auroral emissions. Our results provide a new dataset with information on the peak altitude, geomagnetic location, and auroral intensity of 378 events detected between February and April 2023.
This article is included in the Encyclopedia of Geosciences
Liisa Juusola, Ilkka Virtanen, Spencer Mark Hatch, Heikki Vanhamäki, Maxime Grandin, Noora Partamies, Urs Ganse, Ilja Honkonen, Abiyot Workayehu, Antti Kero, and Minna Palmroth
EGUsphere, https://doi.org/10.5194/egusphere-2025-2394, https://doi.org/10.5194/egusphere-2025-2394, 2025
This preprint is open for discussion and under review for Annales Geophysicae (ANGEO).
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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.
This article is included in the Encyclopedia of Geosciences
Etienne Gavazzi, Andres Spicher, Björn Gustavsson, James Clemmons, Robert Pfaff, and Douglas Rowland
EGUsphere, https://doi.org/10.5194/egusphere-2025-2098, https://doi.org/10.5194/egusphere-2025-2098, 2025
This preprint is open for discussion and under review for Annales Geophysicae (ANGEO).
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Auroral precipitation refers to energetic particles that come down into the upper part of our atmosphere, the ionosphere. There, they collide with atoms and molecules and transfer some of their energy, causing aurora. The most rapid time-variation of this energy deposition and its consequences on the ionosphere are not fully understood. We show here that one can use a new model to study auroral precipitation on sub-second timescales and advance our understanding about small-scale dynamic aurora.
This article is included in the Encyclopedia of Geosciences
Shi Tao, Markku Alho, Ivan Zaitsev, Lucile Turc, Markus Battarbee, Urs Ganse, Yann Pfau-Kempf, and Minna Palmroth
EGUsphere, https://doi.org/10.5194/egusphere-2025-1340, https://doi.org/10.5194/egusphere-2025-1340, 2025
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Plasma convection is the movement of plasma that drags the magnetic field lines with it. Magnetic field in the solar wind interacts with the Earth's magnetic field and drags the dayside field lines of the Earth's magnetosphere toward nightside, causing the plasma inside the magnetosphere to circulate around the Earth in a process called the Dungey Cycle. Our simulation and methodology desribe this cycle in detail and find features in the convection that are not explained by fluid models.
This article is included in the Encyclopedia of Geosciences
Tuomas Häkkilä, Maxime Grandin, Markus Battarbee, Monika E. Szeląg, Markku Alho, Leo Kotipalo, Niilo Kalakoski, Pekka T. Verronen, and Minna Palmroth
Ann. Geophys., 43, 217–240, https://doi.org/10.5194/angeo-43-217-2025, https://doi.org/10.5194/angeo-43-217-2025, 2025
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We study the atmospheric impact of auroral electron precipitation through the novel combination of both magnetospheric modelling 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 more than 200 % in thermospheric odd nitrogen and a corresponding decrease in stratospheric ozone of around 0.8 %. The produced auroral electron precipitation is realistic and shows potential for future studies.
This article is included in the Encyclopedia of Geosciences
Pekka T. Verronen, Akira Mizuno, Yoshizumi Miyoshi, Sandeep Kumar, Taku Nakajima, Shin-Ichiro Oyama, Tomoo Nagahama, Satonori Nozawa, Monika E. Szelag, Tuomas Häkkilä, Niilo Kalakoski, Antti Kero, Esa Turunen, Satoshi Kasahara, Shoichiro Yokota, Kunihiro Keika, Tomoaki Hori, Takefumi Mitani, Takeshi Takashima, and Iku Shinohara
EGUsphere, https://doi.org/10.5194/egusphere-2025-1691, https://doi.org/10.5194/egusphere-2025-1691, 2025
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We use NO column density data from the Syowa station in Antarctica from 2012–2017. We compare these ground-based radiometer observations with results from a global atmosphere model to understand the year-to-year and day-to-day variability, shortcomings of current electron forcing, and how geomagnetic storms are driving the variability of NO. Our results demonstrate an underestimation in the magnitude of day-to-day variability in simulations, which calls for improved electron forcing in models.
This article is included in the Encyclopedia of Geosciences
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.
Björn Linder, Jörg Gumbel, Donal P. Murtagh, Linda Megner, Lukas Krasauskas, Doug Degenstein, Ole Martin Christensen, and Nickolay Ivchenko
EGUsphere, https://doi.org/10.5194/egusphere-2025-493, https://doi.org/10.5194/egusphere-2025-493, 2025
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In this study, the primary instrument carried by the satellite MATS is compared to the OSIRIS instrument onboard the Odin satellite. A total of 36 close approaches between December 2022 and February 2023 were identified and analysed. The comparison reveals that the two instruments have good structural agreement and that MATS detects a signal that is ~20 % stronger than what is measured by OSIRIS.
This article is included in the Encyclopedia of Geosciences
Linda Megner, Jörg Gumbel, Ole Martin Christensen, Björn Linder, Donal Patrick Murtagh, Nickolay Ivchenko, Lukas Krasauskas, Jonas Hedin, Joachim Dillner, Gabriel Giono, Georgi Olentsenko, Louis Kern, and Jacek Stegman
EGUsphere, https://doi.org/10.5194/egusphere-2025-265, https://doi.org/10.5194/egusphere-2025-265, 2025
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The MATS satellite mission studies atmospheric gravity waves, crucial for momentum transport between atmospheric layers. Launched in November 2022, MATS uses a limb-viewing telescope to capture high-resolution images of Noctilucent clouds and airglow, visualizing wave patterns in the high atmosphere. This paper accompanies the public release of the level 1b data set, i.e. calibrated limb images. Later products will provide global maps of gravity wave properties, airglow and Noctilucent clouds.
This article is included in the Encyclopedia of Geosciences
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
Geosci. Model Dev., 18, 511–527, https://doi.org/10.5194/gmd-18-511-2025, https://doi.org/10.5194/gmd-18-511-2025, 2025
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Vlasiator is a kinetic space plasma model that simulates the behavior of plasma, solar wind and magnetic fields in near-Earth space. So far, these simulations have been run without any interaction with the ionosphere, the uppermost layer of Earth's atmosphere. In this paper, 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.
This article is included in the Encyclopedia of Geosciences
Marc Hansen, Daniela Banyś, Mark Clilverd, David Wenzel, Tero Raita, and Mohammed Mainul Hoque
Ann. Geophys., 43, 55–65, https://doi.org/10.5194/angeo-43-55-2025, https://doi.org/10.5194/angeo-43-55-2025, 2025
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The amplitude of subionospheric very low-frequency (VLF) radio signals does not show a symmetrical behavior over the year, which would be expected from its dependency on the solar position. The VLF amplitude rather shows a distinctive sharp decrease around October, which is hence called the "October effect". This study is the first to systematically investigate this October effect, which shows a clear latitudinal dependency.
This article is included in the Encyclopedia of Geosciences
Maxime Grandin, Emma Bruus, Vincent E. Ledvina, Noora Partamies, Mathieu Barthelemy, Carlos Martinis, Rowan Dayton-Oxland, Bea Gallardo-Lacourt, Yukitoshi Nishimura, Katie Herlingshaw, Neethal Thomas, Eero Karvinen, Donna Lach, Marjan Spijkers, and Calle Bergstrand
Geosci. Commun., 7, 297–316, https://doi.org/10.5194/gc-7-297-2024, https://doi.org/10.5194/gc-7-297-2024, 2024
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We carried out a citizen science study of aurora sightings and technological disruptions experienced during the extreme geomagnetic storm of 10 May 2024. We collected reports from 696 observers from over 30 countries via an online survey, supplemented with observations logged in the Skywarden database. We found that the aurora was seen from exceptionally low latitudes and had very bright red and pink hues, suggesting that high fluxes of low-energy electrons from space entered the atmosphere.
This article is included in the Encyclopedia of Geosciences
Guochun Shi, Hanli Liu, Masaki Tsutsumi, Njål Gulbrandsen, Alexander Kozlovsky, Dimitry Pokhotelov, Mark Lester, Kun Wu, and Gunter Stober
EGUsphere, https://doi.org/10.5194/egusphere-2024-3749, https://doi.org/10.5194/egusphere-2024-3749, 2024
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People are increasingly concerned about climate change due to its widespread impacts, including rising temperatures, extreme weather events, and ecosystem disruptions. Addressing these challenges requires urgent global action to reduce greenhouse gas emissions and adapt to a rapidly changing environment.
This article is included in the Encyclopedia of Geosciences
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
Revised manuscript accepted for ANGEO
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Flux ropes are peculiar structures of twisted magnetic field occurring in many regions of space, near Earth and other planets, at the Sun, and in astrophysical objects. We developed a new way of detecting flux ropes in large supercomputer simulations of near-Earth space and we use it to follow the evolution of flux ropes for long distances past the Earth in the flow direction. This will be useful in future studies as these flux ropes are involved in the transport of matter and energy in space.
This article is included in the Encyclopedia of Geosciences
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
EGUsphere, https://doi.org/10.5194/egusphere-2024-3669, https://doi.org/10.5194/egusphere-2024-3669, 2024
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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.
This article is included in the Encyclopedia of Geosciences
Maxime Grandin, Noora Partamies, and Ilkka I. Virtanen
Ann. Geophys., 42, 355–369, https://doi.org/10.5194/angeo-42-355-2024, https://doi.org/10.5194/angeo-42-355-2024, 2024
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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.
This article is included in the Encyclopedia of Geosciences
Leo Kotipalo, Markus Battarbee, Yann Pfau-Kempf, and Minna Palmroth
Geosci. Model Dev., 17, 6401–6413, https://doi.org/10.5194/gmd-17-6401-2024, https://doi.org/10.5194/gmd-17-6401-2024, 2024
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This paper examines a method called adaptive mesh refinement in optimization of the space plasma simulation model Vlasiator. The method locally adjusts resolution in regions which are most relevant to modelling, based on the properties of the plasma. The runs testing this method show that adaptive refinement manages to highlight the desired regions with manageable performance overhead. Performance in larger-scale production runs and mitigation of overhead are avenues of further research.
This article is included in the Encyclopedia of Geosciences
Miriam Sinnhuber, Christina Arras, Stefan Bender, Bernd Funke, Hanli Liu, Daniel R. Marsh, Thomas Reddmann, Eugene Rozanov, Timofei Sukhodolov, Monika E. Szelag, and Jan Maik Wissing
EGUsphere, https://doi.org/10.5194/egusphere-2024-2256, https://doi.org/10.5194/egusphere-2024-2256, 2024
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Formation of nitric oxide NO in the upper atmosphere varies with solar activity. Observations show that it starts a chain of processes in the entire atmosphere affecting the ozone layer and climate system. This is often underestimated in models. We compare five models which show large differences in simulated NO. Analysis of results point out problems related to the oxygen balance, and to the impact of atmospheric waves on dynamics. Both must be modeled well to reproduce the downward coupling.
This article is included in the Encyclopedia of Geosciences
Qinzeng Li, Jiyao Xu, Aditya Riadi Gusman, Hanli Liu, Wei Yuan, Weijun Liu, Yajun Zhu, and Xiao Liu
Atmos. Chem. Phys., 24, 8343–8361, https://doi.org/10.5194/acp-24-8343-2024, https://doi.org/10.5194/acp-24-8343-2024, 2024
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The 2022 Hunga Tonga–Hunga Ha’apai (HTHH) volcanic eruption not only triggered broad-spectrum atmospheric waves but also generated unusual tsunamis which can generate atmospheric gravity waves (AGWs). Multiple strong atmospheric waves were observed in the far-field area of the 2022 HTHH volcano eruption in the upper atmosphere by a ground-based airglow imager network. AGWs caused by tsunamis can propagate to the mesopause region; there is a good match between atmospheric waves and tsunamis.
This article is included in the Encyclopedia of Geosciences
Spencer Mark Hatch, Heikki Vanhamäki, Karl Magnus Laundal, Jone Peter Reistad, Johnathan K. Burchill, Levan Lomidze, David J. Knudsen, Michael Madelaire, and Habtamu Tesfaw
Ann. Geophys., 42, 229–253, https://doi.org/10.5194/angeo-42-229-2024, https://doi.org/10.5194/angeo-42-229-2024, 2024
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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.
This article is included in the Encyclopedia of Geosciences
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
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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.
This article is included in the Encyclopedia of Geosciences
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
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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.
This article is included in the Encyclopedia of Geosciences
Joachim Vogt, Octav Marghitu, Adrian Blagau, Leonie Pick, Nele Stachlys, Stephan Buchert, Theodoros Sarris, Stelios Tourgaidis, Thanasis Balafoutis, Dimitrios Baloukidis, and Panagiotis Pirnaris
Geosci. Instrum. Method. Data Syst., 12, 239–257, https://doi.org/10.5194/gi-12-239-2023, https://doi.org/10.5194/gi-12-239-2023, 2023
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Motivated by recent community interest in a satellite mission to the atmospheric lower thermosphere and ionosphere (LTI) region (100–200 km altitude), the DIPCont project is concerned with the reconstruction quality of vertical profiles of key LTI variables using dual- and single-spacecraft observations. The report introduces the probabilistic DIPCont modeling framework, demonstrates its usage by means of a set of self-consistent parametric non-isothermal models, and discusses first results.
This article is included in the Encyclopedia of Geosciences
Panagiotis Pirnaris and Theodoros Sarris
Ann. Geophys., 41, 339–354, https://doi.org/10.5194/angeo-41-339-2023, https://doi.org/10.5194/angeo-41-339-2023, 2023
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The relation between electron, ion and neutral temperatures in the lower thermosphere–ionosphere (LTI) is key to understanding the energy balance and transfer between species. However, their simultaneous measurement is rare in the LTI. Based on data from the AE-C, AE-D, AE-E and DE-2 satellites of the 1970s and 1980s, a large number of events where neutrals are hotter than ions are identified and statistically analyzed. Potential mechanisms that could trigger these events are proposed.
This article is included in the Encyclopedia of Geosciences
Masatoshi Yamauchi and Urban Brändström
Geosci. Instrum. Method. Data Syst., 12, 71–90, https://doi.org/10.5194/gi-12-71-2023, https://doi.org/10.5194/gi-12-71-2023, 2023
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Potential users of all-sky aurora images even include power companies, tourists, and aurora enthusiasts. However, these potential users are normally not familiar with interpreting these images. To make them comprehensive for more users, we developed an automatic evaluation system of auroral activity level. The method involves two steps: first making a simple set of numbers that describes the auroral activity and then further simplifying them into several levels (Level 6 is an auroral explosion).
This article is included in the Encyclopedia of Geosciences
Cornelius Csar Jude H. Salinas, Dong L. Wu, Jae N. Lee, Loren C. Chang, Liying Qian, and Hanli Liu
Atmos. Chem. Phys., 23, 1705–1730, https://doi.org/10.5194/acp-23-1705-2023, https://doi.org/10.5194/acp-23-1705-2023, 2023
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Upper mesospheric carbon monoxide's (CO) photochemical lifetime is longer than dynamical timescales. This work uses satellite observations and model simulations to establish that the migrating diurnal tide and its seasonal and interannual variabilities drive CO primarily through vertical advection. Vertical advection is a transport process that is currently difficult to observe. This work thus shows that we can use CO as a tracer for vertical advection across seasonal and interannual timescales.
This article is included in the Encyclopedia of Geosciences
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
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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.
This article is included in the Encyclopedia of Geosciences
Qinzeng Li, Jiyao Xu, Hanli Liu, Xiao Liu, and Wei Yuan
Atmos. Chem. Phys., 22, 12077–12091, https://doi.org/10.5194/acp-22-12077-2022, https://doi.org/10.5194/acp-22-12077-2022, 2022
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We use ground-based airglow network observations, reanalysis data, and satellite observations to explore the propagation process of concentric gravity waves (CGWs) excited by a typhoon between the troposphere, stratosphere, mesosphere, and thermosphere. We find that CGWs in the mesosphere are generated directly by the typhoon but the CGW observed in the thermosphere may be excited by CGW dissipation in the mesosphere, rather than directly excited by a typhoon and propagated to the thermosphere.
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Carsten Baumann, Antti Kero, Shikha Raizada, Markus Rapp, Michael P. Sulzer, Pekka T. Verronen, and Juha Vierinen
Ann. Geophys., 40, 519–530, https://doi.org/10.5194/angeo-40-519-2022, https://doi.org/10.5194/angeo-40-519-2022, 2022
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The Arecibo radar was used to probe free electrons of the ionized atmosphere between 70 and 100 km altitude. This is also the altitude region were meteors evaporate and form secondary particulate matter, the so-called meteor smoke particles (MSPs). Free electrons attach to these MSPs when the sun is below the horizon and cause a drop in the number of free electrons, which are the subject of these measurements. We also identified a different number of free electrons during sunset and sunrise.
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Irina Mironova, Miriam Sinnhuber, Galina Bazilevskaya, Mark Clilverd, Bernd Funke, Vladimir Makhmutov, Eugene Rozanov, Michelle L. Santee, Timofei Sukhodolov, and Thomas Ulich
Atmos. Chem. Phys., 22, 6703–6716, https://doi.org/10.5194/acp-22-6703-2022, https://doi.org/10.5194/acp-22-6703-2022, 2022
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From balloon measurements, we detected unprecedented, extremely powerful, electron precipitation over the middle latitudes. The robustness of this event is confirmed by satellite observations of electron fluxes and chemical composition, as well as by ground-based observations of the radio signal propagation. The applied chemistry–climate model shows the almost complete destruction of ozone in the mesosphere over the region where high-energy electrons were observed.
This article is included in the Encyclopedia of Geosciences
David A. Newnham, Mark A. Clilverd, William D. J. Clark, Michael Kosch, Pekka T. Verronen, and Alan E. E. Rogers
Atmos. Meas. Tech., 15, 2361–2376, https://doi.org/10.5194/amt-15-2361-2022, https://doi.org/10.5194/amt-15-2361-2022, 2022
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Ozone (O3) is an important trace gas in the mesosphere and lower thermosphere (MLT), affecting heating rates and chemistry. O3 profiles measured by the Ny-Ålesund Ozone in the Mesosphere Instrument agree with Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) for winter night-time, but autumn twilight SABER abundances are up to 50 % higher. O3 abundances in the MLT from two different SABER channels also show significant differences for both autumn twilight and summer daytime.
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Filomena Catapano, Stephan Buchert, Enkelejda Qamili, Thomas Nilsson, Jerome Bouffard, Christian Siemes, Igino Coco, Raffaella D'Amicis, Lars Tøffner-Clausen, Lorenzo Trenchi, Poul Erik Holmdahl Olsen, and Anja Stromme
Geosci. Instrum. Method. Data Syst., 11, 149–162, https://doi.org/10.5194/gi-11-149-2022, https://doi.org/10.5194/gi-11-149-2022, 2022
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The quality control and validation activities performed by the Swarm data quality team reveal the good-quality LPs. The analysis demonstrated that the current baseline plasma data products are improved with respect to previous baseline. The LPs have captured the ionospheric plasma variability over more than half of a solar cycle, revealing the data quality dependence on the solar activity. The quality of the LP data will further improve promotion of their application to a broad range of studies.
This article is included in the Encyclopedia of Geosciences
Daniel K. Whiter, Hanna Sundberg, Betty S. Lanchester, Joshua Dreyer, Noora Partamies, Nickolay Ivchenko, Marco Zaccaria Di Fraia, Rosie Oliver, Amanda Serpell-Stevens, Tiffany Shaw-Diaz, and Thomas Braunersreuther
Ann. Geophys., 39, 975–989, https://doi.org/10.5194/angeo-39-975-2021, https://doi.org/10.5194/angeo-39-975-2021, 2021
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This paper presents an analysis of high-resolution optical and radar observations of a phenomenon called fragmented aurora-like emissions (FAEs) observed close to aurora in the high Arctic. The observations suggest that FAEs are not caused by high-energy electrons or protons entering the atmosphere along Earth's magnetic field and are, therefore, not aurora. The speeds of the FAEs and their internal dynamics were measured and used to evaluate theories for how the FAEs are produced.
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Clayton Cantrall and Tomoko Matsuo
Atmos. Meas. Tech., 14, 6917–6928, https://doi.org/10.5194/amt-14-6917-2021, https://doi.org/10.5194/amt-14-6917-2021, 2021
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This paper presents a new technique to determine temperature in the thermosphere from observations of far ultraviolet radiation emitted by molecular nitrogen. The technique utilizes a ratio of two far ultraviolet spectral channels to capture the thermosphere temperature signal. Applying the technique to NASA GOLD observations results in temperatures that agree well with other thermosphere observations during a geomagnetic disturbance.
This article is included in the Encyclopedia of Geosciences
Jianfei Wu, Wuhu Feng, Han-Li Liu, Xianghui Xue, Daniel Robert Marsh, and John Maurice Campbell Plane
Atmos. Chem. Phys., 21, 15619–15630, https://doi.org/10.5194/acp-21-15619-2021, https://doi.org/10.5194/acp-21-15619-2021, 2021
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Metal layers occur in the MLT region (80–120 km) from the ablation of cosmic dust. The latest lidar observations show these metals can reach a height approaching 200 km, which is challenging to explain. We have developed the first global simulation incorporating the full life cycle of metal atoms and ions. The model results compare well with lidar and satellite observations of the seasonal and diurnal variation of the metals and demonstrate the importance of ion mass and ion-neutral coupling.
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Vertti Tarvus, Lucile Turc, Markus Battarbee, Jonas Suni, Xóchitl Blanco-Cano, Urs Ganse, Yann Pfau-Kempf, Markku Alho, Maxime Dubart, Maxime Grandin, Andreas Johlander, Konstantinos Papadakis, and Minna Palmroth
Ann. Geophys., 39, 911–928, https://doi.org/10.5194/angeo-39-911-2021, https://doi.org/10.5194/angeo-39-911-2021, 2021
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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.
This article is included in the Encyclopedia of Geosciences
Pekka T. Verronen, Antti Kero, Noora Partamies, Monika E. Szeląg, Shin-Ichiro Oyama, Yoshizumi Miyoshi, and Esa Turunen
Ann. Geophys., 39, 883–897, https://doi.org/10.5194/angeo-39-883-2021, https://doi.org/10.5194/angeo-39-883-2021, 2021
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This paper is the first to simulate and analyse the pulsating aurorae impact on middle atmosphere on monthly/seasonal timescales. We find that pulsating aurorae have the potential to make a considerable contribution to the total energetic particle forcing and increase the impact on upper stratospheric odd nitrogen and ozone in the polar regions. Thus, it should be considered in atmospheric and climate simulations.
This article is included in the Encyclopedia of Geosciences
Gunter Stober, Ales Kuchar, Dimitry Pokhotelov, Huixin Liu, Han-Li Liu, Hauke Schmidt, Christoph Jacobi, Kathrin Baumgarten, Peter Brown, Diego Janches, Damian Murphy, Alexander Kozlovsky, Mark Lester, Evgenia Belova, Johan Kero, and Nicholas Mitchell
Atmos. Chem. Phys., 21, 13855–13902, https://doi.org/10.5194/acp-21-13855-2021, https://doi.org/10.5194/acp-21-13855-2021, 2021
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Little is known about the climate change of wind systems in the mesosphere and lower thermosphere at the edge of space at altitudes from 70–110 km. Meteor radars represent a well-accepted remote sensing technique to measure winds at these altitudes. Here we present a state-of-the-art climatological interhemispheric comparison using continuous and long-lasting observations from worldwide distributed meteor radars from the Arctic to the Antarctic and sophisticated general circulation models.
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Florine Enengl, Noora Partamies, Nickolay Ivchenko, and Lisa Baddeley
Ann. Geophys., 39, 795–809, https://doi.org/10.5194/angeo-39-795-2021, https://doi.org/10.5194/angeo-39-795-2021, 2021
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Energetic particle precipitation has the potential to change the neutral atmospheric temperature at the bottom of the ionosphere. We have searched for events and investigated a possible correlation between lower-ionosphere electron density enhancements and simultaneous neutral temperature changes. Six of the 10 analysed events are associated with a temperature decrease of 10–20K. The events change the chemical composition in the mesosphere, and the temperatures are probed at lower altitudes.
This article is included in the Encyclopedia of Geosciences
Vladimir B. Belakhovsky, Yaqi Jin, and Wojciech J. Miloch
Ann. Geophys., 39, 687–700, https://doi.org/10.5194/angeo-39-687-2021, https://doi.org/10.5194/angeo-39-687-2021, 2021
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The high-latitude ionosphere has a very dynamic structure and causes a negative influence via radio wave propagation on, for example, global positioning system (GPS) signals and satellite communication. In this study, we have determined which type of high-latitude ionosphere disturbance has a stronger influence on GPS signals using a GPS receiver on Svalbard. It is shown that a substorm ionosphere disturbance leads to stronger GPS signal fluctuations than other types of ionosphere disturbances.
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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.
This article is included in the Encyclopedia of Geosciences
Bingkun Yu, Xianghui Xue, Christopher J. Scott, Jianfei Wu, Xinan Yue, Wuhu Feng, Yutian Chi, Daniel R. Marsh, Hanli Liu, Xiankang Dou, and John M. C. Plane
Atmos. Chem. Phys., 21, 4219–4230, https://doi.org/10.5194/acp-21-4219-2021, https://doi.org/10.5194/acp-21-4219-2021, 2021
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A long-standing mystery of metal ions within Es layers in the Earth's upper atmosphere is the marked seasonal dependence, with a summer maximum and a winter minimum. We report a large-scale winter-to-summer transport of metal ions from 6-year multi-satellite observations and worldwide ground-based stations. A global atmospheric circulation is responsible for the phenomenon. Our results emphasise the effect of this atmospheric circulation on the transport of composition in the upper atmosphere.
This article is included in the Encyclopedia of Geosciences
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
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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.
This article is included in the Encyclopedia of Geosciences
Joshua Dreyer, Noora Partamies, Daniel Whiter, Pål G. Ellingsen, Lisa Baddeley, and Stephan C. Buchert
Ann. Geophys., 39, 277–288, https://doi.org/10.5194/angeo-39-277-2021, https://doi.org/10.5194/angeo-39-277-2021, 2021
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Small-scale auroral features are still being discovered and are not well understood. Where aurorae are caused by particle precipitation, the newly reported fragmented aurora-like emissions (FAEs) seem to be locally generated in the ionosphere (hence,
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aurora-like). We analyse data from multiple instruments located near Longyearbyen to derive their main characteristics. They seem to occur as two types in a narrow altitude region (individually or in regularly spaced groups).
Tong Dang, Binzheng Zhang, Jiuhou Lei, Wenbin Wang, Alan Burns, Han-li Liu, Kevin Pham, and Kareem A. Sorathia
Geosci. Model Dev., 14, 859–873, https://doi.org/10.5194/gmd-14-859-2021, https://doi.org/10.5194/gmd-14-859-2021, 2021
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This paper describes a numerical treatment (ring average) to relax the time step in finite-difference schemes when using spherical and cylindrical coordinates with axis singularities. The ring average is used to develop a high-resolution thermosphere–ionosphere coupled community model. The technique is a significant improvement in space weather modeling capability, and it can also be adapted to more general finite-difference solvers for hyperbolic equations in spherical and polar geometries.
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
Tuomas Häkkilä, Pekka T. Verronen, Luis Millán, Monika E. Szeląg, Niilo Kalakoski, and Antti Kero
Ann. Geophys., 38, 1299–1312, https://doi.org/10.5194/angeo-38-1299-2020, https://doi.org/10.5194/angeo-38-1299-2020, 2020
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The atmospheric impacts of energetic particle precipitation (EPP) can be useful in understanding the uncertainties of measuring the precipitation. Hence, information on how strong of an EPP flux has observable atmospheric impacts is needed. In this study, we find such threshold flux values using odd hydrogen concentrations from both satellite observations and model simulations. We consider the effects of solar proton events and radiation belt electron precipitation in the middle atmosphere.
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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.
This article is included in the Encyclopedia of Geosciences
Jia Jia, Antti Kero, Niilo Kalakoski, Monika E. Szeląg, and Pekka T. Verronen
Atmos. Chem. Phys., 20, 14969–14982, https://doi.org/10.5194/acp-20-14969-2020, https://doi.org/10.5194/acp-20-14969-2020, 2020
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Recent studies have reported up to a 10 % average decrease of lower stratospheric ozone at 20 km altitude following solar proton events (SPEs). Our study uses 49 events that occurred after the launch of Aura MLS (July 2004–now) and 177 events that occurred in the WACCM-D simulation period (Jan 1989–Dec 2012) to evaluate ozone changes following SPEs. The statistical and case-by-case studies show no solid evidence of SPE's direct impact on the lower stratospheric ozone.
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Xiao Liu, Jiyao Xu, Jia Yue, and Hanli Liu
Atmos. Chem. Phys., 20, 14437–14456, https://doi.org/10.5194/acp-20-14437-2020, https://doi.org/10.5194/acp-20-14437-2020, 2020
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Large wind shears in the mesosphere and lower thermosphere are recognized as a common phenomenon. Simulation and ground-based observations show that the main contributor of large wind shears is gravity waves. We present a method of deriving wind shears induced by gravity waves according to the linear theory and using the global temperature observations by SABER (Sounding of the Atmosphere using Broadband Emission Radiometry). Our results agree well with observations and model simulations.
This article is included in the Encyclopedia of Geosciences
Patrick Mungufeni, Sripathi Samireddipalle, Yenca Migoya-Orué, and Yong Ha Kim
Ann. Geophys., 38, 1203–1215, https://doi.org/10.5194/angeo-38-1203-2020, https://doi.org/10.5194/angeo-38-1203-2020, 2020
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This study developed a model of total electron content (TEC) over the African region. The TEC data were derived from radio occultation measurements done by the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites. Data during geomagnetically quiet time for the years 2008–2011 and 2013–2017 were binned according to local time, seasons, solar flux level, geographic longitude, and dip latitude. Cubic B splines were used to fit the data for the model.
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Masatoshi Yamauchi, Magnar G. Johnsen, Carl-Fredrik Enell, Anders Tjulin, Anna Willer, and Dmitry A. Sormakov
Ann. Geophys., 38, 1159–1170, https://doi.org/10.5194/angeo-38-1159-2020, https://doi.org/10.5194/angeo-38-1159-2020, 2020
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The paper reports a new finding on space weather effects at around 70–75 ° geographic latitudes. We found that X flares cause an unexpectedly strong ionospheric current driven by solar flares. The effect is as large as a substorm that is known to cause strong auroras and may enhance ongoing substorms. However, it has been overlooked in the past due to the narrow latitudinal range at high latitudes. Since severe magnetic storms often occur with X flares, this may cause geomagnetic hazards.
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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.
This article is included in the Encyclopedia of Geosciences
Sharon Aol, Stephan Buchert, Edward Jurua, and Marco Milla
Ann. Geophys., 38, 1063–1080, https://doi.org/10.5194/angeo-38-1063-2020, https://doi.org/10.5194/angeo-38-1063-2020, 2020
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Ionospheric irregularities are a common phenomenon in the low-latitude ionosphere. In this paper, we compared simultaneous observations of plasma plumes by the JULIA radar, ionogram spread F generated from ionosonde observations installed at the Jicamarca Radio Observatory, and irregularities observed in situ by Swarm to determine whether Swarm in situ observations can be used as indicators of the presence of plasma plumes and spread F on the ground.
This article is included in the Encyclopedia of Geosciences
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
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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.
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Stephan C. Buchert
Ann. Geophys., 38, 1019–1030, https://doi.org/10.5194/angeo-38-1019-2020, https://doi.org/10.5194/angeo-38-1019-2020, 2020
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Winds in the Earth's upper atmosphere cause magnetic and electric variations both at the ground and in space all over the Earth. According to the model of entangled dynamos the true cause is wind differences between regions in the Northern and Southern Hemispheres that are connected by the Earth's dipole-like magnetic field. The power produced in the southern dynamo heats the northern upper atmosphere and vice versa. The dynamos exist owing to this entanglement, an analogy to quantum mechanics.
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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.
This article is included in the Encyclopedia of Geosciences
Niilo Kalakoski, Pekka T. Verronen, Annika Seppälä, Monika E. Szeląg, Antti Kero, and Daniel R. Marsh
Atmos. Chem. Phys., 20, 8923–8938, https://doi.org/10.5194/acp-20-8923-2020, https://doi.org/10.5194/acp-20-8923-2020, 2020
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Effects of solar proton events (SPEs) on middle atmosphere chemistry were studied using the WACCM-D chemistry–climate model, including an improved representation of lower ionosphere ion chemistry. This study includes 66 events in the years 1989–2012 and uses a statistical approach to determine the impact of the improved chemistry scheme. The differences shown highlight the importance of ion chemistry in models used to study energetic particle precipitation.
This article is included in the Encyclopedia of Geosciences
Sam Tuttle, Betty Lanchester, Björn Gustavsson, Daniel Whiter, Nickolay Ivchenko, Robert Fear, and Mark Lester
Ann. Geophys., 38, 845–859, https://doi.org/10.5194/angeo-38-845-2020, https://doi.org/10.5194/angeo-38-845-2020, 2020
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Electric fields in the atmosphere near dynamic aurora are important in the physics of the electric circuit within the Earth's magnetic field. Oxygen ions emit light as they move under the influence of these electric fields; the flow of this emission is used to find the electric field at high temporal resolution. The solution needs two other simultaneous measurements of auroral emissions to give key parameters such as the auroral energy. The electric fields increase with brightness of the aurora.
This article is included in the Encyclopedia of Geosciences
Pekka T. Verronen, Daniel R. Marsh, Monika E. Szeląg, and Niilo Kalakoski
Ann. Geophys., 38, 833–844, https://doi.org/10.5194/angeo-38-833-2020, https://doi.org/10.5194/angeo-38-833-2020, 2020
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This paper is the first to study how the representation of the magnetic-local-time (MLT) dependency of electron precipitation impacts middle-atmospheric-ozone response on monthly timescales. We use a state-of-the-art chemistry–climate model with detailed lower-ionospheric chemistry for an advanced representation of atmospheric impacts of electron forcing. We find that the use of daily zonal-mean electron forcing will provide an accurate ozone response in long-term climate simulations.
This article is included in the Encyclopedia of Geosciences
João Teixeira da Encarnação, Pieter Visser, Daniel Arnold, Aleš Bezdek, Eelco Doornbos, Matthias Ellmer, Junyi Guo, Jose van den IJssel, Elisabetta Iorfida, Adrian Jäggi, Jaroslav Klokocník, Sandro Krauss, Xinyuan Mao, Torsten Mayer-Gürr, Ulrich Meyer, Josef Sebera, C. K. Shum, Chaoyang Zhang, Yu Zhang, and Christoph Dahle
Earth Syst. Sci. Data, 12, 1385–1417, https://doi.org/10.5194/essd-12-1385-2020, https://doi.org/10.5194/essd-12-1385-2020, 2020
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Although not the primary mission of the Swarm three-satellite constellation, the sensors on these satellites are accurate enough to measure the melting and accumulation of Earth’s ice reservoirs, precipitation cycles, floods, and droughts, amongst others. Swarm sees these changes well compared to the dedicated GRACE satellites at spatial scales of roughly 1500 km. Swarm confirms most GRACE observations, such as the large ice melting in Greenland and the wet and dry seasons in the Amazon.
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
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
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
Sharon Aol, Stephan Buchert, and Edward Jurua
Ann. Geophys., 38, 243–261, https://doi.org/10.5194/angeo-38-243-2020, https://doi.org/10.5194/angeo-38-243-2020, 2020
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During the night, in the F region, equatorial ionospheric irregularities manifest as plasma depletions observed by satellites and may cause radio signals to fluctuate. We checked the distribution traits of ionospheric F-region irregularities in the low latitudes using 16 Hz electron density observations made by the faceplate onboard Swarm satellites. Using the high-resolution faceplate data, we were able to identify ionospheric irregularities of scales of only a few hundred metres.
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Masatoshi Yamauchi
Ann. Geophys., 37, 1197–1222, https://doi.org/10.5194/angeo-37-1197-2019, https://doi.org/10.5194/angeo-37-1197-2019, 2019
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Terrestrial ion transport and total escape are synthesized, with stress on the high-latitude polar region and the inner magnetosphere where Custer significantly improved knowledge. After estimating the outflow flux and destinations, complicated ion dynamics in the inner magnetosphere was classified and summarized, through which more than half the O+ is finally lost to space. Together with direct escapes, total O+ escape is high enough to influence the evolution of the biosphere.
This article is included in the Encyclopedia of Geosciences
Anasuya Aruliah, Matthias Förster, Rosie Hood, Ian McWhirter, and Eelco Doornbos
Ann. Geophys., 37, 1095–1120, https://doi.org/10.5194/angeo-37-1095-2019, https://doi.org/10.5194/angeo-37-1095-2019, 2019
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Winds near the top of the atmosphere are expected to be the same at all heights for a given location by assuming high viscosity in rarefied gases. However, wind measurements from satellite drag at 350–400 km altitude were found to be up to 2 times larger than optical measurements at ∼240 km. Satellites provide global measurements, and ground-based FPIs provide long-term monitoring at single sites. So we must understand this inconsistency to model and predict atmospheric behaviour correctly.
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
Costel Bunescu, Joachim Vogt, Octav Marghitu, and Adrian Blagau
Ann. Geophys., 37, 347–373, https://doi.org/10.5194/angeo-37-347-2019, https://doi.org/10.5194/angeo-37-347-2019, 2019
David A. Newnham, Mark A. Clilverd, Michael Kosch, Annika Seppälä, and Pekka T. Verronen
Atmos. Meas. Tech., 12, 1375–1392, https://doi.org/10.5194/amt-12-1375-2019, https://doi.org/10.5194/amt-12-1375-2019, 2019
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A simulation study has been carried out to investigate the potential for observing ozone and hydroxyl radical abundances in the mesosphere and lower thermosphere using ground-based passive microwave radiometry. In the polar middle atmosphere these chemical species respond strongly to geomagnetic activity associated with space weather. The results show that measuring diurnal variations in ozone and hydroxyl from high-latitude Northern Hemisphere and Antarctic locations would be possible.
This article is included in the Encyclopedia of Geosciences
Xinhua Wei, Chunlin Cai, Henri Rème, Iannis Dandouras, and George Parks
Ann. Geophys. Discuss., https://doi.org/10.5194/angeo-2018-124, https://doi.org/10.5194/angeo-2018-124, 2018
Revised manuscript not accepted
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Observations of flapping current sheet in the magnetotail are presented to reveal their intrinsic excitation mechanism induced by alternating north-south asymmetric ion populations in the sheet center. The results suggest that nonadiabatic ions play a substantial role to determine current sheet dynamics, both its bulk mechanical instability and current profiles.
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Tarique A. Siddiqui, Astrid Maute, Nick Pedatella, Yosuke Yamazaki, Hermann Lühr, and Claudia Stolle
Ann. Geophys., 36, 1545–1562, https://doi.org/10.5194/angeo-36-1545-2018, https://doi.org/10.5194/angeo-36-1545-2018, 2018
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Extreme meteorological events such as SSWs induce variabilities in the ionosphere by modulating the atmospheric tides, and these variabilities can be comparable to a moderate geomagnetic storm. The equatorial electrojet (EEJ) is a narrow ribbon of current flowing over the dip equator in the ionosphere and is particularly sensitive to tidal changes. In this study, we use ground-magnetic measurements to investigate the semidiurnal solar and lunar tidal variabilities of the EEJ during SSWs.
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Gabriel Giono, Boris Strelnikov, Heiner Asmus, Tristan Staszak, Nickolay Ivchenko, and Franz-Josef Lübken
Atmos. Meas. Tech., 11, 5299–5314, https://doi.org/10.5194/amt-11-5299-2018, https://doi.org/10.5194/amt-11-5299-2018, 2018
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Energetic photons, such as ultraviolet light, are able to eject electrons from a material surface, thus creating an electrical current, also called a photocurrent. A proper estimation of this photocurrent can be crucial for space- or rocket-borne particle detectors, as it can dominate over the currents that are of scientific interest (induced by charged particles, for example). This article outlines the design for photocurrent modelling and for experimental confirmation in a laboratory.
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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.
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
Chao Xiong, Claudia Stolle, and Jaeheung Park
Ann. Geophys., 36, 679–693, https://doi.org/10.5194/angeo-36-679-2018, https://doi.org/10.5194/angeo-36-679-2018, 2018
Erkki Kyrölä, Monika E. Andersson, Pekka T. Verronen, Marko Laine, Simo Tukiainen, and Daniel R. Marsh
Atmos. Chem. Phys., 18, 5001–5019, https://doi.org/10.5194/acp-18-5001-2018, https://doi.org/10.5194/acp-18-5001-2018, 2018
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In this work we compare three key constituents of the middle atmosphere (ozone, NO2, and NO3) from the GOMOS satellite instrument with the WACCM model. We find that in the stratosphere (below 50 km) ozone differences are very small, but in the mesosphere large deviations are found. GOMOS and WACCM NO2 agree reasonably well except in the polar areas. These differences can be connected to the solar particle storms. For NO3, WACCM results agree with GOMOS with a very high correlation.
This article is included in the Encyclopedia of Geosciences
Libin Weng, Jiuhou Lei, Eelco Doornbos, Hanxian Fang, and Xiankang Dou
Ann. Geophys., 36, 489–496, https://doi.org/10.5194/angeo-36-489-2018, https://doi.org/10.5194/angeo-36-489-2018, 2018
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Thermospheric mass density from the GOCE satellite for Sun-synchronous orbits between 83.5° S and 83.5° N normalized to 270 km during 2009–2013 has been used to develop our GOCE model at dawn/dusk local solar time sectors based on the empirical orthogonal function (EOF) method. We find that both amplitude and phase of the seasonal variations have strong latitudinal and solar activity dependences, and the annual asymmetry and effect of the Sun–Earth distance vary with latitude and solar activity.
This article is included in the Encyclopedia of Geosciences
Quang Thai Trinh, Manfred Ern, Eelco Doornbos, Peter Preusse, and Martin Riese
Ann. Geophys., 36, 425–444, https://doi.org/10.5194/angeo-36-425-2018, https://doi.org/10.5194/angeo-36-425-2018, 2018
Masatoshi Yamauchi and Rikard Slapak
Ann. Geophys., 36, 1–12, https://doi.org/10.5194/angeo-36-1-2018, https://doi.org/10.5194/angeo-36-1-2018, 2018
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Extraction of the solar wind kinetic energy (∆K) by mass loading of escaping O+ is modelled in the exterior cusp and plasma mantle of the Earth. We found ∆K proportional to mass flux of escaping ions and square of solar wind velocity, but independent to the other parameters. The amount is sufficient to power the cusp field-aligned currents, further enhancing ion escape through Joule heating of the ionospheric ions, completing positive feedback to enhance escape with geomagnetic activities.
This article is included in the Encyclopedia of Geosciences
Audrey Schillings, Hans Nilsson, Rikard Slapak, Masatoshi Yamauchi, and Lars-Göran Westerberg
Ann. Geophys., 35, 1341–1352, https://doi.org/10.5194/angeo-35-1341-2017, https://doi.org/10.5194/angeo-35-1341-2017, 2017
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The Earth's atmosphere is constantly losing ions and in particular oxygen ions. This phenomenon is important to understand the atmospheric evolution on a large timescale. In this study, the O+ outflow is estimated during six extreme geomagnetic storms using the European Cluster mission data. These estimations are compared with average magnetospheric conditions and show that during those six extreme storms, the O+ outflow is approximately 2 orders of magnitude higher.
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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.
This article is included in the Encyclopedia of Geosciences
Nickolay Ivchenko, Nicola M. Schlatter, Hanna Dahlgren, Yasunobu Ogawa, Yuka Sato, and Ingemar Häggström
Ann. Geophys., 35, 1143–1149, https://doi.org/10.5194/angeo-35-1143-2017, https://doi.org/10.5194/angeo-35-1143-2017, 2017
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Photo-electrons and secondary electrons from particle precipitation enhance the incoherent scatter plasma line to levels sufficient for detection. A plasma line gives an accurate measure of the electron density and can be used to estimate electron temperature. The occurrence of plasma line enhancements in the EISCAT Svalbard Radar data was investigated. During summer daytime hours the plasma line is detectable in up to 90 % of the data. In winter time the occurrence is a few percent.
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
Rikard Slapak, Maria Hamrin, Timo Pitkänen, Masatoshi Yamauchi, Hans Nilsson, Tomas Karlsson, and Audrey Schillings
Ann. Geophys., 35, 869–877, https://doi.org/10.5194/angeo-35-869-2017, https://doi.org/10.5194/angeo-35-869-2017, 2017
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The ion total transports in the near-Earth plasma sheet have been investigated and quantified. Specifically, the net O+ transport is about 1024 s−1 in the earthward direction, which is 1 order of magnitude smaller than the typical O+ ionospheric outflows, strongly indicating that most outflow will eventually escape, leading to significant atmospheric loss. The study also shows that low-velocity flows (< 100 km s−1) dominate the mass transport in the near-Earth plasma sheet.
This article is included in the Encyclopedia of Geosciences
Katja Matthes, Bernd Funke, Monika E. Andersson, Luke Barnard, Jürg Beer, Paul Charbonneau, Mark A. Clilverd, Thierry Dudok de Wit, Margit Haberreiter, Aaron Hendry, Charles H. Jackman, Matthieu Kretzschmar, Tim Kruschke, Markus Kunze, Ulrike Langematz, Daniel R. Marsh, Amanda C. Maycock, Stergios Misios, Craig J. Rodger, Adam A. Scaife, Annika Seppälä, Ming Shangguan, Miriam Sinnhuber, Kleareti Tourpali, Ilya Usoskin, Max van de Kamp, Pekka T. Verronen, and Stefan Versick
Geosci. Model Dev., 10, 2247–2302, https://doi.org/10.5194/gmd-10-2247-2017, https://doi.org/10.5194/gmd-10-2247-2017, 2017
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The solar forcing dataset for climate model experiments performed for the upcoming IPCC report is described. This dataset provides the radiative and particle input of solar variability on a daily basis from 1850 through to 2300. With this dataset a better representation of natural climate variability with respect to the output of the Sun is provided which provides the most sophisticated and comprehensive respresentation of solar variability that has been used in climate model simulations so far.
This article is included in the Encyclopedia of Geosciences
Rikard Slapak, Audrey Schillings, Hans Nilsson, Masatoshi Yamauchi, Lars-Göran Westerberg, and Iannis Dandouras
Ann. Geophys., 35, 721–731, https://doi.org/10.5194/angeo-35-721-2017, https://doi.org/10.5194/angeo-35-721-2017, 2017
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In this study, we have used Cluster satellite data to quantify the ionospheric oxygen ion (O+) escape into the solar wind and its dependence on geomagnetic activity. During times of high activity, the escape may be 2 orders of magnitude higher than under quiet conditions, strongly suggesting that the escape rate was much higher when the Sun was young. The results are important for future studies regarding atmospheric loss over geological timescales.
This article is included in the Encyclopedia of Geosciences
Theodore E. Sarris and Xinlin Li
Ann. Geophys., 35, 629–638, https://doi.org/10.5194/angeo-35-629-2017, https://doi.org/10.5194/angeo-35-629-2017, 2017
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In this paper we describe a novel way to approximate the decomposition of magnetospheric ultra low-frequency (ULF) wave power in key azimuthal wavenumbers m, which is a parameter describing the number of azimuthal wavelengths that fit within a particle drift orbit. This is a critical parameter that is required in estimates of the rates of radial diffusion, and we show for the first time that there is a local time and geomagnetic activity dependence in the distribution of power in wavenumbers m.
This article is included in the Encyclopedia of Geosciences
Yunxia Yuan, Nickolay Ivchenko, Gunnar Tibert, Marin Stanev, Jonas Hedin, and Jörg Gumbel
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2017-91, https://doi.org/10.5194/amt-2017-91, 2017
Revised manuscript has not been submitted
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The paper presents a method to determine altitude profile of atmospheric density, temperature and wind by means of analysing the reconstructed trajectory of a rigid falling sphere released from a sounding rocket. The trajectory reconstruction is achieved by post-flight analysis of GPS raw data gathered in the sphere. A comparison of the results with independent measurements is presented, with good agreement of the falling sphere results with other sources in the stratosphere.
This article is included in the Encyclopedia of Geosciences
Hanna Dahlgren, Betty S. Lanchester, Nickolay Ivchenko, and Daniel K. Whiter
Ann. Geophys., 35, 493–503, https://doi.org/10.5194/angeo-35-493-2017, https://doi.org/10.5194/angeo-35-493-2017, 2017
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Pulsating aurora are ubiquitous events that constitute a large amount of energy transfer to the ionosphere. Still there are unsolved issues regarding their formation. Using high-resolution optical and radar data, we find that it is the flux of high-energy electrons that get reduced during the OFF period of the pulsations. We also report on dips in brightness at the transition between ON and OFF, and asymmetric rise and fall times, which may have implications for understanding the pulsations.
This article is included in the Encyclopedia of Geosciences
Hanna Dahlgren, Nicola M. Schlatter, Nickolay Ivchenko, Lorenz Roth, and Alexander Karlsson
Ann. Geophys., 35, 475–479, https://doi.org/10.5194/angeo-35-475-2017, https://doi.org/10.5194/angeo-35-475-2017, 2017
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Anomalous strong echoes with three frequency peaks are occasionally seen with incoherent scatter radars in the ionosphere near 200 km altitude at high latitudes. We investigate how they relate to electron precipitation, by finding the resulting peak electron density and the height of the peak, respectively. We find that occurrence rate increases with density and decreases with height, indicating a correlation between the echoes and precipitating electrons with high energy and energy flux.
This article is included in the Encyclopedia of Geosciences
Bernd Funke, William Ball, Stefan Bender, Angela Gardini, V. Lynn Harvey, Alyn Lambert, Manuel López-Puertas, Daniel R. Marsh, Katharina Meraner, Holger Nieder, Sanna-Mari Päivärinta, Kristell Pérot, Cora E. Randall, Thomas Reddmann, Eugene Rozanov, Hauke Schmidt, Annika Seppälä, Miriam Sinnhuber, Timofei Sukhodolov, Gabriele P. Stiller, Natalia D. Tsvetkova, Pekka T. Verronen, Stefan Versick, Thomas von Clarmann, Kaley A. Walker, and Vladimir Yushkov
Atmos. Chem. Phys., 17, 3573–3604, https://doi.org/10.5194/acp-17-3573-2017, https://doi.org/10.5194/acp-17-3573-2017, 2017
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Simulations from eight atmospheric models have been compared to tracer and temperature observations from seven satellite instruments in order to evaluate the energetic particle indirect effect (EPP IE) during the perturbed northern hemispheric (NH) winter 2008/2009. Models are capable to reproduce the EPP IE in dynamically and geomagnetically quiescent NH winter conditions. The results emphasize the need for model improvements in the dynamical representation of elevated stratopause events.
This article is included in the Encyclopedia of Geosciences
Xuguang Cai, Tao Yuan, and Han-Li Liu
Ann. Geophys., 35, 181–188, https://doi.org/10.5194/angeo-35-181-2017, https://doi.org/10.5194/angeo-35-181-2017, 2017
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Atmospheric gravity waves play highly important roles in the dynamic and chemical processes in the upper atmosphere. To assess their magnitude, continuous full diurnal cycle measurements of temperature perturbations are necessary. In this paper we have calculated the large-scale gravity wave modulations between 85 and 99 km altitude based on the measurements by a unique Na lidar at Utah State University in the month of September from 2011 to 2015. The waves with period of 3–5 h dominate.
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
Hermann Lühr, Tao Huang, Simon Wing, Guram Kervalishvili, Jan Rauberg, and Haje Korth
Ann. Geophys., 34, 901–915, https://doi.org/10.5194/angeo-34-901-2016, https://doi.org/10.5194/angeo-34-901-2016, 2016
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ESA's constellation mission Swarm makes it possible for the first time to determine field-aligned currents (FACs) reliably in the ionosphere. FACs are able to transport energy from the solar wind to the Earth and heat the upper atmosphere. Here we investigate FAC structures that have been missed by previous satellite missions. Most of them are found poleward of the northern light zone. The energy sources seem to be located on the nightside of Earth about 100 000 km away.
This article is included in the Encyclopedia of Geosciences
Tamás Kovács, John M. C. Plane, Wuhu Feng, Tibor Nagy, Martyn P. Chipperfield, Pekka T. Verronen, Monika E. Andersson, David A. Newnham, Mark A. Clilverd, and Daniel R. Marsh
Geosci. Model Dev., 9, 3123–3136, https://doi.org/10.5194/gmd-9-3123-2016, https://doi.org/10.5194/gmd-9-3123-2016, 2016
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This study was completed on D-region atmospheric model development. The sophisticated 3-D Whole Atmosphere Community Climate Model (WACCM) and the 1-D Sodynkalä Ion and Neutral Chemistry Model (SIC) were combined in order to provide a detailed, accurate model (WACCM-SIC) that considers the processes taking place in solar proton events. The original SIC model was reduced by mechanism reduction, which provided an accurate sub-mechanism (rSIC, WACCM-rSIC) of the original model.
This article is included in the Encyclopedia of Geosciences
Davide Masutti, Günther March, Aaron J. Ridley, and Jan Thoemel
Ann. Geophys., 34, 725–736, https://doi.org/10.5194/angeo-34-725-2016, https://doi.org/10.5194/angeo-34-725-2016, 2016
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The Global Ionosphere Thermosphere Model has been validated against flight data. The validation shows a linear dependency of the neutral density values with respect to the solar activity. In particular, the thermosphere model shows an over-predicting or under-predicting behaviour under high or low solar activity respectively. The reasons for such behaviour can be attributed to an erroneous implementation of the chemical processes or the gas transport properties in the model.
This article is included in the Encyclopedia of Geosciences
Theodore E. Sarris and Xinlin Li
Ann. Geophys., 34, 565–571, https://doi.org/10.5194/angeo-34-565-2016, https://doi.org/10.5194/angeo-34-565-2016, 2016
Sheng-Yang Gu, Han-Li Liu, Xiankang Dou, and Tao Li
Atmos. Chem. Phys., 16, 4885–4896, https://doi.org/10.5194/acp-16-4885-2016, https://doi.org/10.5194/acp-16-4885-2016, 2016
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The influences of sudden stratospheric warming in the Northern Hemisphere on quasi-2-day waves are studied with both observations and simulations. We found the energy of W3 is transferred to W2 through the nonlinear interaction with SPW1 and the instability at winter mesopause could provide additional amplification for W3. The summer easterly is enhanced during SSW, which is more favorable for the propagation of quasi-2-day waves.
This article is included in the Encyclopedia of Geosciences
N. Y. Ganushkina, M. W. Liemohn, S. Dubyagin, I. A. Daglis, I. Dandouras, D. L. De Zeeuw, Y. Ebihara, R. Ilie, R. Katus, M. Kubyshkina, S. E. Milan, S. Ohtani, N. Ostgaard, J. P. Reistad, P. Tenfjord, F. Toffoletto, S. Zaharia, and O. Amariutei
Ann. Geophys., 33, 1369–1402, https://doi.org/10.5194/angeo-33-1369-2015, https://doi.org/10.5194/angeo-33-1369-2015, 2015
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A number of current systems exist in the Earth's magnetosphere. It is very difficult to identify local measurements as belonging to a specific current system. Therefore, there are different definitions of supposedly the same current, leading to unnecessary controversy. This study presents a robust collection of these definitions of current systems in geospace, particularly in the near-Earth nightside magnetosphere, as viewed from a variety of observational and computational analysis techniques.
This article is included in the Encyclopedia of Geosciences
E. Lee, G. K. Parks, S. Y. Fu, M. Fillingim, Y. B. Cui, J. Hong, I. Dandouras, and H. Rème
Ann. Geophys., 33, 1263–1269, https://doi.org/10.5194/angeo-33-1263-2015, https://doi.org/10.5194/angeo-33-1263-2015, 2015
K. Konstantinidis and T. Sarris
Geosci. Model Dev., 8, 2967–2975, https://doi.org/10.5194/gmd-8-2967-2015, https://doi.org/10.5194/gmd-8-2967-2015, 2015
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The 2nd & 3rd adiabatic invariants (in particular their proxies I & L*) are commonly used to characterize charged particle motion in a magnetic field. However care should be taken when calculating them, as the assumption of their conservation is not valid everywhere in the Earth’s magnetosphere. In this paper we compare calculations of I and L* using LANLstar, SPENVIS, IRBEM and a 3D particle tracer, and we map the areas in the Earth’s magnetosphere where I & L* can be assumed to be conserved.
This article is included in the Encyclopedia of Geosciences
N. M. Schlatter, V. Belyey, B. Gustavsson, N. Ivchenko, D. Whiter, H. Dahlgren, S. Tuttle, and T. Grydeland
Ann. Geophys., 33, 837–844, https://doi.org/10.5194/angeo-33-837-2015, https://doi.org/10.5194/angeo-33-837-2015, 2015
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The high-latitude ionosphere is a dynamic region where particle precipitation leads to various phenomena including wave instability and turbulence. Anomalous echoes related to aurora are observed in ground-based radar observations of the ionosphere. These echoes indicate enhanced ion acoustic fluctuations. In this article, we show that the origin of the echo is located in or close to the region of particle precipitation and that the echo region itself is limited to hundreds of meters.
This article is included in the Encyclopedia of Geosciences
J. Park, H. Lühr, C. Stolle, G. Malhotra, J. B. H. Baker, S. Buchert, and R. Gill
Ann. Geophys., 33, 829–835, https://doi.org/10.5194/angeo-33-829-2015, https://doi.org/10.5194/angeo-33-829-2015, 2015
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Though high-latitude plasma convection has been monitored with a number of methods, more independent measurements are still warranted. In this study we introduce an automatic method to estimate along-track plasma drift velocity in the high-latitude ionosphere using the Swarm constellation. The obtained velocity is in qualitative agreement with Super Dual Auroral Radar Network (SuperDARN) data. The method can be generalized to any satellite constellations in pearls-on-a-string configurations.
This article is included in the Encyclopedia of Geosciences
T. Živković, S. Buchert, P. Ritter, L. Palin, and H. Opgenoorth
Ann. Geophys., 33, 623–635, https://doi.org/10.5194/angeo-33-623-2015, https://doi.org/10.5194/angeo-33-623-2015, 2015
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In this paper we analyze 21 conjunctions between the Cluster and CHAMP satellites while they were passing magnetic cusp during relatively quiet solar activity. Only three of the conjunctions reveal field-aligned currents on both satellites as well as neutral density enhancement in the thermosphere. Poynting and electron energy fluxes (EEF) as well as Joule heating were computed and the conclusion is that for these weak events EEF has the strongest contribution to the observed density increase.
This article is included in the Encyclopedia of Geosciences
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.
This article is included in the Encyclopedia of Geosciences
G. K. Parks, E. Lee, S. Y. Fu, M. Fillingim, I. Dandouras, Y. B. Cui, J. Hong, and H. Rème
Ann. Geophys., 33, 333–344, https://doi.org/10.5194/angeo-33-333-2015, https://doi.org/10.5194/angeo-33-333-2015, 2015
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Ions from Earth's ionosphere continually escape into space. This article examines ions escaping the auroral oval, a region in the polar region of Earth where auroras occur. Previous works have shown that ionospheric ions escape during active auroras, and more as the intensity of the aurora increases. In contrast, we have examined times of no auroras and find that ions are still escaping the auroral ionosphere. These escaping ions are an important source of auroral ions in the magnetosphere.
This article is included in the Encyclopedia of Geosciences
T. A. Siddiqui, H. Lühr, C. Stolle, and J. Park
Ann. Geophys., 33, 235–243, https://doi.org/10.5194/angeo-33-235-2015, https://doi.org/10.5194/angeo-33-235-2015, 2015
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This paper presents the long-term observations of lunar tidal signatures in the equatorial electrojet (EEJ) and their relation to stratospheric sudden warming (SSW) events. We propose an approach to estimate the occurrence of SSW events before their direct observations (before 1952) from the magnetic field observations at Huancayo.
This article is included in the Encyclopedia of Geosciences
A. Blagau, G. Paschmann, B. Klecker, and O. Marghitu
Ann. Geophys., 33, 79–91, https://doi.org/10.5194/angeo-33-79-2015, https://doi.org/10.5194/angeo-33-79-2015, 2015
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Rotational discontinuities (RDs) in plasma allow a magnetic connection between different plasma regimes. One of their defining relations describes a balance between changes in plasma mass density and pressure anisotropy. The paper uses the high-time-resolution data from the Cluster satellites to directly test that relation at the terrestrial magnetopause, when standard analysis predicts that this boundary behaves like an RD. The experimental evidence shows that the said relation is not fulfilled
This article is included in the Encyclopedia of Geosciences
M. C. Kelley, F. S. Rodrigues, R. F. Pfaff, and J. Klenzing
Ann. Geophys., 32, 1169–1175, https://doi.org/10.5194/angeo-32-1169-2014, https://doi.org/10.5194/angeo-32-1169-2014, 2014
A. Varsani, C. J. Owen, A. N. Fazakerley, C. Forsyth, A. P. Walsh, M. André, I. Dandouras, and C. M. Carr
Ann. Geophys., 32, 1093–1117, https://doi.org/10.5194/angeo-32-1093-2014, https://doi.org/10.5194/angeo-32-1093-2014, 2014
E. S. Miller, H. Kil, J. J. Makela, R. A. Heelis, E. R. Talaat, and A. Gross
Ann. Geophys., 32, 959–965, https://doi.org/10.5194/angeo-32-959-2014, https://doi.org/10.5194/angeo-32-959-2014, 2014
X. Liu, J. Xu, H.-L. Liu, J. Yue, and W. Yuan
Ann. Geophys., 32, 543–552, https://doi.org/10.5194/angeo-32-543-2014, https://doi.org/10.5194/angeo-32-543-2014, 2014
A. Blagau, I. Dandouras, A. Barthe, S. Brunato, G. Facskó, and V. Constantinescu
Geosci. Instrum. Method. Data Syst., 3, 49–58, https://doi.org/10.5194/gi-3-49-2014, https://doi.org/10.5194/gi-3-49-2014, 2014
R. A. Stoneback and R. A. Heelis
Ann. Geophys., 32, 421–429, https://doi.org/10.5194/angeo-32-421-2014, https://doi.org/10.5194/angeo-32-421-2014, 2014
G. N. Kervalishvili and H. Lühr
Ann. Geophys., 32, 249–261, https://doi.org/10.5194/angeo-32-249-2014, https://doi.org/10.5194/angeo-32-249-2014, 2014
M. Yamauchi, Y. Ebihara, H. Nilsson, and I. Dandouras
Ann. Geophys., 32, 83–90, https://doi.org/10.5194/angeo-32-83-2014, https://doi.org/10.5194/angeo-32-83-2014, 2014
W. R. Coley, R. A. Stoneback, R. A. Heelis, and M. R. Hairston
Ann. Geophys., 32, 69–75, https://doi.org/10.5194/angeo-32-69-2014, https://doi.org/10.5194/angeo-32-69-2014, 2014
M. E. Andersson, P. T. Verronen, C. J. Rodger, M. A. Clilverd, and S. Wang
Atmos. Chem. Phys., 14, 1095–1105, https://doi.org/10.5194/acp-14-1095-2014, https://doi.org/10.5194/acp-14-1095-2014, 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
J. Klenzing, A. G. Burrell, R. A. Heelis, J. D. Huba, R. Pfaff, and F. Simões
Ann. Geophys., 31, 2147–2156, https://doi.org/10.5194/angeo-31-2147-2013, https://doi.org/10.5194/angeo-31-2147-2013, 2013
N. M. Schlatter, N. Ivchenko, T. Sergienko, B. Gustavsson, and B. U. E. Brändström
Ann. Geophys., 31, 1681–1687, https://doi.org/10.5194/angeo-31-1681-2013, https://doi.org/10.5194/angeo-31-1681-2013, 2013
M. Yamauchi, I. Dandouras, H. Rème, R. Lundin, and L. M. Kistler
Ann. Geophys., 31, 1569–1578, https://doi.org/10.5194/angeo-31-1569-2013, https://doi.org/10.5194/angeo-31-1569-2013, 2013
I. Dandouras
Ann. Geophys., 31, 1143–1153, https://doi.org/10.5194/angeo-31-1143-2013, https://doi.org/10.5194/angeo-31-1143-2013, 2013
N. M. Schlatter, N. Ivchenko, B. Gustavsson, T. Leyser, and M. Rietveld
Ann. Geophys., 31, 1103–1108, https://doi.org/10.5194/angeo-31-1103-2013, https://doi.org/10.5194/angeo-31-1103-2013, 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
P. T. Verronen and R. Lehmann
Ann. Geophys., 31, 909–956, https://doi.org/10.5194/angeo-31-909-2013, https://doi.org/10.5194/angeo-31-909-2013, 2013
J. Markkanen, T. Nygrén, M. Markkanen, M. Voiculescu, and A. Aikio
Ann. Geophys., 31, 859–870, https://doi.org/10.5194/angeo-31-859-2013, https://doi.org/10.5194/angeo-31-859-2013, 2013
C. P. Escoubet, J. Berchem, K. J. Trattner, F. Pitout, R. Richard, M. G. G. T. Taylor, J. Soucek, B. Grison, H. Laakso, A. Masson, M. Dunlop, I. Dandouras, H. Reme, A. Fazakerley, and P. Daly
Ann. Geophys., 31, 713–723, https://doi.org/10.5194/angeo-31-713-2013, https://doi.org/10.5194/angeo-31-713-2013, 2013
G. N. Kervalishvili and H. Lühr
Ann. Geophys., 31, 541–554, https://doi.org/10.5194/angeo-31-541-2013, https://doi.org/10.5194/angeo-31-541-2013, 2013
W. Reid, P. Achtert, N. Ivchenko, P. Magnusson, T. Kuremyr, V. Shepenkov, and G. Tibert
Atmos. Meas. Tech., 6, 777–785, https://doi.org/10.5194/amt-6-777-2013, https://doi.org/10.5194/amt-6-777-2013, 2013
Y. L. Zhou, S. Y. Ma, R. S. Liu, H. Luehr, and E. Doornbos
Ann. Geophys., 31, 15–30, https://doi.org/10.5194/angeo-31-15-2013, https://doi.org/10.5194/angeo-31-15-2013, 2013
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Short summary
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.
This is a review paper that summarises the current understanding of the lower...
