Articles | Volume 34, issue 7
https://doi.org/10.5194/angeo-34-609-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/angeo-34-609-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Regular paper
| 
14 Jul 2016
Regular paper |
| 14 Jul 2016
Two-point observations of low-frequency waves at 67P/Churyumov-Gerasimenko during the descent of PHILAE: comparison of RPCMAG and ROMAP
Institut für Geophysik und extraterrestrische Physik, TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
Hans-Ulrich Auster
Institut für Geophysik und extraterrestrische Physik, TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
Gerhard Berghofer
Institut für Weltraumforschung, Schmiedlstraße 6, 8042 Graz, Austria
Chris Carr
Imperial College London, Exhibition Road, London SW7 2AZ, UK
Emanuele Cupido
Imperial College London, Exhibition Road, London SW7 2AZ, UK
Karl-Heinz Fornaçon
Institut für Geophysik und extraterrestrische Physik, TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
Charlotte Goetz
Institut für Geophysik und extraterrestrische Physik, TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
Philip Heinisch
Institut für Geophysik und extraterrestrische Physik, TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
Christoph Koenders
Institut für Geophysik und extraterrestrische Physik, TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
Bernd Stoll
Institut für Geophysik und extraterrestrische Physik, TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
Bruce T. Tsurutani
Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive Pasadena, CA 91109, USA
Claire Vallat
Rosetta Science Ground Segment, European Space Astronomy Centre, 28691 Villanueva de la Cañada, Madrid, Spain
Martin Volwerk
Institut für Weltraumforschung, Schmiedlstraße 6, 8042 Graz, Austria
Karl-Heinz Glassmeier
Institut für Geophysik und extraterrestrische Physik, TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
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I. Richter, C. Koenders, H.-U. Auster, D. Frühauff, C. Götz, P. Heinisch, C. Perschke, U. Motschmann, B. Stoll, K. Altwegg, J. Burch, C. Carr, E. Cupido, A. Eriksson, P. Henri, R. Goldstein, J.-P. Lebreton, P. Mokashi, Z. Nemeth, H. Nilsson, M. Rubin, K. Szegö, B. T. Tsurutani, C. Vallat, M. Volwerk, and K.-H. Glassmeier
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Ann. Geophys., 32, 1441–1453, https://doi.org/10.5194/angeo-32-1441-2014, https://doi.org/10.5194/angeo-32-1441-2014, 2014
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We discuss three flybys (within an 8-day time span) of comet 1P/Halley by VEGA 1, 2 and Giotto. Looking at two different plasma phenomena: mirror mode waves and field line draping; we study the differences in SW--comet interaction between these three flybys. We find that on this time scale (comparable to Rosetta's orbits) there is a significant difference, both caused by changing outgassing rate of the comet and changes in the solar wind. We discuss implications for Rosetta RPC observations.
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Ann. Geophys., 31, 2201–2206, https://doi.org/10.5194/angeo-31-2201-2013, https://doi.org/10.5194/angeo-31-2201-2013, 2013
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Revised manuscript accepted for NPG
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On February 03, 2022, SpaceX launched a new group of satellites for its Starlink constellation. This launch simultaneously released 49 satellites in orbits between 200 km and 250 km height. The launches occurred during a geomagnetic storm, followed by a second one. There was an immediate loss of 32 satellites. The satellite losses may have been caused by an unusually high level of atmospheric drag (unexplained by current theory/modeling) or a high level of satellite collisions.
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The plasma environment of comet 67P provides a unique laboratory to study plasma phenomena in the solar system. Previous studies have reported the existence of mirror modes at 67P but no further systematic investigation has so far been done. This study aims to learn more about these waves. We investigate the magnetic field measured by Rosetta and find 565 mirror mode signatures. The detected mirror modes are likely generated upstream of the observation and have been modified by the plasma.
This article is included in the Encyclopedia of Geosciences
Martin Volwerk, Cyril Simon Wedlund, David Mautner, Sebastián Rojas Mata, Gabriella Stenberg Wieser, Yoshifumi Futaana, Christian Mazelle, Diana Rojas-Castillo, César Bertucci, and Magda Delva
Ann. Geophys., 41, 389–408, https://doi.org/10.5194/angeo-41-389-2023, https://doi.org/10.5194/angeo-41-389-2023, 2023
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Freshly created ions in solar wind start gyrating around the interplanetary magnetic field. When they cross the bow shock, they get an extra kick, and this increases the plasma pressure against the magnetic pressure. This leads to the creation of so-called mirror modes, regions where the magnetic field decreases in strength and the plasma density increases. These structures help in exploring how energy is transferred from the ions to the magnetic field and where around Venus this is happening.
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Cyril Simon Wedlund, Martin Volwerk, Christian Mazelle, Sebastián Rojas Mata, Gabriella Stenberg Wieser, Yoshifumi Futaana, Jasper Halekas, Diana Rojas-Castillo, César Bertucci, and Jared Espley
Ann. Geophys., 41, 225–251, https://doi.org/10.5194/angeo-41-225-2023, https://doi.org/10.5194/angeo-41-225-2023, 2023
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Martin Volwerk, Beatriz Sánchez-Cano, Daniel Heyner, Sae Aizawa, Nicolas André, Ali Varsani, Johannes Mieth, Stefano Orsini, Wolfgang Baumjohann, David Fischer, Yoshifumi Futaana, Richard Harrison, Harald Jeszenszky, Iwai Kazumasa, Gunter Laky, Herbert Lichtenegger, Anna Milillo, Yoshizumi Miyoshi, Rumi Nakamura, Ferdinand Plaschke, Ingo Richter, Sebastián Rojas Mata, Yoshifumi Saito, Daniel Schmid, Daikou Shiota, and Cyril Simon Wedlund
Ann. Geophys., 39, 811–831, https://doi.org/10.5194/angeo-39-811-2021, https://doi.org/10.5194/angeo-39-811-2021, 2021
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On 15 October 2020, BepiColombo used Venus as a gravity assist to change its orbit to reach Mercury in late 2021. During this passage of Venus, the spacecraft entered into Venus's magnetotail at a distance of 70 Venus radii from the planet. We have studied the magnetic field and plasma data and find that Venus's magnetotail is highly active. This is caused by strong activity in the solar wind, where just before the flyby a coronal mass ejection interacted with the magnetophere of Venus.
This article is included in the Encyclopedia of Geosciences
Katharina Ostaszewski, Karl-Heinz Glassmeier, Charlotte Goetz, Philip Heinisch, Pierre Henri, Sang A. Park, Hendrik Ranocha, Ingo Richter, Martin Rubin, and Bruce Tsurutani
Ann. Geophys., 39, 721–742, https://doi.org/10.5194/angeo-39-721-2021, https://doi.org/10.5194/angeo-39-721-2021, 2021
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Plasma waves are an integral part of cometary physics, as they facilitate the transfer of energy and momentum. From intermediate to strong activity, nonlinear asymmetric plasma and magnetic field enhancements dominate the inner coma of 67P/CG. We present a statistical survey of these structures from December 2014 to June 2016, facilitated by Rosetta's unprecedented long mission duration. Using a 1D MHD model, we show they can be described as a combination of nonlinear and dissipative effects.
This article is included in the Encyclopedia of Geosciences
Daniel Schmid, Yasuhito Narita, Ferdinand Plaschke, Martin Volwerk, Rumi Nakamura, and Wolfgang Baumjohann
Ann. Geophys., 39, 563–570, https://doi.org/10.5194/angeo-39-563-2021, https://doi.org/10.5194/angeo-39-563-2021, 2021
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In this work we present the first analytical magnetosheath plasma flow model for the space environment around Mercury. The proposed model is relatively simple to implement and provides the possibility to trace the flow lines inside the Hermean magnetosheath. It can help to determine the the local plasma conditions of a spacecraft in the magnetosheath exclusively on the basis of the upstream solar wind parameters.
This article is included in the Encyclopedia of Geosciences
Charlotte Goetz, Herbert Gunell, Fredrik Johansson, Kristie LLera, Hans Nilsson, Karl-Heinz Glassmeier, and Matthew G. G. T. Taylor
Ann. Geophys., 39, 379–396, https://doi.org/10.5194/angeo-39-379-2021, https://doi.org/10.5194/angeo-39-379-2021, 2021
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Boundaries in the plasma around comet 67P separate regions with different properties. Many have been identified, including a new boundary called an infant bow shock. Here, we investigate how the plasma and fields behave at this boundary and where it can be found. The main result is that the infant bow shock occurs at intermediate activity and intermediate distances to the comet. Most plasma parameters behave as expected; however, some inconsistencies indicate that the boundary is non-stationary.
This article is included in the Encyclopedia of Geosciences
Martin Volwerk, David Mautner, Cyril Simon Wedlund, Charlotte Goetz, Ferdinand Plaschke, Tomas Karlsson, Daniel Schmid, Diana Rojas-Castillo, Owen W. Roberts, and Ali Varsani
Ann. Geophys., 39, 239–253, https://doi.org/10.5194/angeo-39-239-2021, https://doi.org/10.5194/angeo-39-239-2021, 2021
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The magnetic field in the solar wind is not constant but varies in direction and strength. One of these variations shows a strong local reduction of the magnetic field strength and is called a magnetic hole. These holes are usually an indication that there is, or has been, a temperature difference in the plasma of the solar wind, with the temperature along the magnetic field lower than perpendicular. The MMS spacecraft data have been used to study the characteristics of these holes near Earth.
This article is included in the Encyclopedia of Geosciences
Herbert Gunell, Charlotte Goetz, Elias Odelstad, Arnaud Beth, Maria Hamrin, Pierre Henri, Fredrik L. Johansson, Hans Nilsson, and Gabriella Stenberg Wieser
Ann. Geophys., 39, 53–68, https://doi.org/10.5194/angeo-39-53-2021, https://doi.org/10.5194/angeo-39-53-2021, 2021
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When the magnetised solar wind meets the plasma surrounding a comet, the magnetic field is enhanced in front of the comet, and the field lines are draped around it. This happens because electric currents are induced in the plasma. When these currents flow through the plasma, they can generate waves. In this article we present observations of ion acoustic waves, which is a kind of sound wave in the plasma, detected by instruments on the Rosetta spacecraft near comet 67P/Churyumov–Gerasimenko.
This article is included in the Encyclopedia of Geosciences
Ovidiu Dragoş Constantinescu, Hans-Ulrich Auster, Magda Delva, Olaf Hillenmaier, Werner Magnes, and Ferdinand Plaschke
Geosci. Instrum. Method. Data Syst., 9, 451–469, https://doi.org/10.5194/gi-9-451-2020, https://doi.org/10.5194/gi-9-451-2020, 2020
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We propose a gradiometer-based technique for cleaning multi-sensor magnetic field data acquired on board spacecraft. The technique takes advantage on the fact that the maximum-variance direction of many AC disturbances on board spacecraft does not change over time. We apply the proposed technique to the SOSMAG instrument on board GeoKompsat-2A. We analyse the performance and limitations of the technique and discuss in detail how various disturbances are removed.
This article is included in the Encyclopedia of Geosciences
Daniel Schmid, Ferdinand Plaschke, Yasuhito Narita, Daniel Heyner, Johannes Z. D. Mieth, Brian J. Anderson, Martin Volwerk, Ayako Matsuoka, and Wolfgang Baumjohann
Ann. Geophys., 38, 823–832, https://doi.org/10.5194/angeo-38-823-2020, https://doi.org/10.5194/angeo-38-823-2020, 2020
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Recently, the two-spacecraft mission BepiColombo was launched to explore Mercury. To measure the magnetic field precisely, in-flight calibration of the magnetometer offset is needed. Usually, the offset is evaluated from magnetic field observations in the solar wind. Since one of the spacecraft will remain within Mercury's magnetic environment, we examine an alternative calibration method. We show that this method is applicable and may be a valuable tool to determine the offset accurately.
This article is included in the Encyclopedia of Geosciences
Karl-Heinz Glassmeier
Hist. Geo Space. Sci., 11, 71–80, https://doi.org/10.5194/hgss-11-71-2020, https://doi.org/10.5194/hgss-11-71-2020, 2020
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The German Geophysical Society was founded in 1922 as the Deutsche Seismologische Vereinigung. One of the 24 founders of this society was Karl Friedrich Almstedt. Born in 1891 and deceased in 1964, Almstedt represents a generation of academics and scientists who grew up during the decline of the European empires, experiencing the devastations of the two World Wars and the cruelties of the Nazi era as well as the resurrection of academic and cultural life in post-war Germany.
This article is included in the Encyclopedia of Geosciences
Guoqiang Wang, Tielong Zhang, Mingyu Wu, Daniel Schmid, Yufei Hao, and Martin Volwerk
Ann. Geophys., 38, 309–318, https://doi.org/10.5194/angeo-38-309-2020, https://doi.org/10.5194/angeo-38-309-2020, 2020
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Currents are believed to exist in mirror-mode structures and to be self-consistent with the magnetic field depression. Bipolar currents are found in two ion-scale magnetic dips. The bipolar current in a small-size magnetic dip is mainly contributed by electron velocities, which is mainly formed by the magnetic gradient–curvature drift. For another large-size magnetic dip, the bipolar current is mainly caused by an ion bipolar velocity, which can be explained by the ion drift motions.
This article is included in the Encyclopedia of Geosciences
Bruce T. Tsurutani, Gurbax S. Lakhina, and Rajkumar Hajra
Nonlin. Processes Geophys., 27, 75–119, https://doi.org/10.5194/npg-27-75-2020, https://doi.org/10.5194/npg-27-75-2020, 2020
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Current space weather problems are discussed for young researchers. We have discussed some of the major problems that need to be solved for space weather forecasting to become a reality.
This article is included in the Encyclopedia of Geosciences
Martin Volwerk, Charlotte Goetz, Ferdinand Plaschke, Tomas Karlsson, Daniel Heyner, and Brian Anderson
Ann. Geophys., 38, 51–60, https://doi.org/10.5194/angeo-38-51-2020, https://doi.org/10.5194/angeo-38-51-2020, 2020
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The magnetic field that is carried by the solar wind slowly decreases in strength as it moves further from the Sun. However, there are sometimes localized decreases in the magnetic field strength, called magnetic holes. These are small structures where the magnetic field strength decreases to less than 50 % of the surroundings and the plasma density increases. This paper presents a statistical study of the behaviour of these holes between Mercury and Venus using MESSENGER data.
This article is included in the Encyclopedia of Geosciences
Anthony J. Mannucci, Ryan McGranaghan, Xing Meng, Bruce T. Tsurutani, and Olga P. Verkhoglyadova
Ann. Geophys. Discuss., https://doi.org/10.5194/angeo-2019-108, https://doi.org/10.5194/angeo-2019-108, 2019
Preprint withdrawn
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The interaction between the Earth's environment and the electrically charged gas known as the solar wind is highly complex and has been under study for decades. We use a universal principle of physics – the relativity principle – to gain physical insight into this interaction. We apply this principle to physical processes that occur during geomagnetic storms. We clarify how the solar wind ultimately causes currents to flow between the Earth's upper atmosphere and space.
This article is included in the Encyclopedia of Geosciences
Ferdinand Plaschke, Hans-Ulrich Auster, David Fischer, Karl-Heinz Fornaçon, Werner Magnes, Ingo Richter, Dragos Constantinescu, and Yasuhito Narita
Geosci. Instrum. Method. Data Syst., 8, 63–76, https://doi.org/10.5194/gi-8-63-2019, https://doi.org/10.5194/gi-8-63-2019, 2019
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Raw output of spacecraft magnetometers has to be converted into meaningful units and coordinate systems before it is usable for scientific applications. This conversion is defined by 12 calibration parameters, 8 of which are more easily determined in flight if the spacecraft is spinning. We present theory and advanced algorithms to determine these eight parameters. They take into account the physical magnetometer and spacecraft behavior, making them superior to previously published algorithms.
This article is included in the Encyclopedia of Geosciences
Evelyn Liebert, Christian Nabert, and Karl-Heinz Glassmeier
Ann. Geophys., 36, 1073–1080, https://doi.org/10.5194/angeo-36-1073-2018, https://doi.org/10.5194/angeo-36-1073-2018, 2018
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At the bow shock the solar wind is slowed down in front of Earth's magnetosphere. This is accompanied by a gain in strength of the magnetic field, which implies that the bow shock carries electric currents. We present the a comprehensive statistical study of bow shock currents making use of multi-point data collected by Cluster spacecraft. We find that the currents depend on the shock geometry and the interplanetary magnetic field and are in good accordance with theory and simulation results.
This article is included in the Encyclopedia of Geosciences
Gurbax S. Lakhina, Bruce T. Tsurutani, George J. Morales, Annick Pouquet, Masahiro Hoshino, Juan Alejandro Valdivia, Yasuhito Narita, and Roger Grimshaw
Nonlin. Processes Geophys., 25, 477–479, https://doi.org/10.5194/npg-25-477-2018, https://doi.org/10.5194/npg-25-477-2018, 2018
Martin Volwerk
Ann. Geophys., 36, 831–839, https://doi.org/10.5194/angeo-36-831-2018, https://doi.org/10.5194/angeo-36-831-2018, 2018
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Using Voyager 1 observations of Jupiter's Io plasma torus, we have determined the location of maximum brightness depending on longitude and the location of Jupiter’s moon Io. We obtain a third viewing direction of the torus (after Voyager 2 and ground observations) and thus two locations, left and right of Jupiter, which are important for the correct modeling of this structure. We also find that a narrow ribbon-like structure only appears when the brightness of the torus exceeds a certain value.
This article is included in the Encyclopedia of Geosciences
Fernando L. Guarnieri, Bruce T. Tsurutani, Luis E. A. Vieira, Rajkumar Hajra, Ezequiel Echer, Anthony J. Mannucci, and Walter D. Gonzalez
Nonlin. Processes Geophys., 25, 67–76, https://doi.org/10.5194/npg-25-67-2018, https://doi.org/10.5194/npg-25-67-2018, 2018
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In this work we developed a method to obtain a time series named as AE* which is well correlated with the geomagnetic AE index. In this process, wavelet filtering is applied to interplanetary solar wind data from spacecrafts around the L1 libration point. This geomagnetic indicator AE* can be obtained well before the AE index release in its final form, and it can be used to feed models for geomagnetic effects, such as the relativistic electrons, giving forecasts ~ 1 to 2 days in advance.
This article is included in the Encyclopedia of Geosciences
Gurbax S. Lakhina and Bruce T. Tsurutani
Nonlin. Processes Geophys., 24, 745–750, https://doi.org/10.5194/npg-24-745-2017, https://doi.org/10.5194/npg-24-745-2017, 2017
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A preliminary estimate of the drag force per unit mass on typical low-Earth-orbiting satellites moving through the ionosphere during Carrington-type super magnetic storms is calculated by a simple first-order model which takes into account the ion-neutral drag between the upward-moving oxygen ions and O neutral atoms. It is shown that oxygen ions and atoms can be uplifted to 850 km altitude, where they produce about 40 times more satellite drag per unit mass than normal.
This article is included in the Encyclopedia of Geosciences
Sudong Xiao, Tielong Zhang, Guoqiang Wang, Martin Volwerk, Yasong Ge, Daniel Schmid, Rumi Nakamura, Wolfgang Baumjohann, and Ferdinand Plaschke
Ann. Geophys., 35, 1015–1022, https://doi.org/10.5194/angeo-35-1015-2017, https://doi.org/10.5194/angeo-35-1015-2017, 2017
Evelyn Liebert, Christian Nabert, Christopher Perschke, Karl-Heinz Fornaçon, and Karl-Heinz Glassmeier
Ann. Geophys., 35, 645–657, https://doi.org/10.5194/angeo-35-645-2017, https://doi.org/10.5194/angeo-35-645-2017, 2017
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We present a statistical survey of current magnitudes, directions and locations at the high-latitude day-side magnetopause using Cluster's multi-spacecraft data. Our results show that the magnetopause current flow directions match expectations based on existing models and simulations. Current magnitudes are in correspondence with former studies. In addition, we observe a varying location of the currents with respect to changes in the ambient plasma properties.
This article is included in the Encyclopedia of Geosciences
Christian Nabert, Carsten Othmer, and Karl-Heinz Glassmeier
Ann. Geophys., 35, 613–628, https://doi.org/10.5194/angeo-35-613-2017, https://doi.org/10.5194/angeo-35-613-2017, 2017
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The interaction of the solar wind with a planetary magnetic field causes electrical currents that modify the magnetic field distribution around the planet. We present an approach to estimating the planetary magnetic field contribution by minimizing the misfit between simulation results and in situ spacecraft data. The approach is developed with respect to the upcoming BepiColombo mission to Mercury aimed at determining the planet's magnetic field.
This article is included in the Encyclopedia of Geosciences
Christian Nabert, Daniel Heyner, and Karl-Heinz Glassmeier
Ann. Geophys., 35, 465–474, https://doi.org/10.5194/angeo-35-465-2017, https://doi.org/10.5194/angeo-35-465-2017, 2017
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Knowledge of planetary magnetic fields provides deep insights into the structure and dynamics of planets. Due to the interaction of a planet with the solar wind plasma, electrical currents are generated which modify the planetary magnetic field outside the planet. New methods are presented to estimate the planetary magnetic field contribution from spacecraft observations. A reduced model of the interaction relates the time-varying observations to the planetary magnetic field magnitude.
This article is included in the Encyclopedia of Geosciences
Dennis Frühauff, Johannes Z. D. Mieth, and Karl-Heinz Glassmeier
Ann. Geophys., 35, 253–262, https://doi.org/10.5194/angeo-35-253-2017, https://doi.org/10.5194/angeo-35-253-2017, 2017
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The determination of the polytropic index the plasma sheet of Earth's magnetosphere using THEMIS data. The data set reveals that the active magnetotail density and pressure data are well correlated. Yet, considering broad distributions of specific entropies, the evaluation is best performed on shorter timescales.
This article is included in the Encyclopedia of Geosciences
Dennis Frühauff, Ferdinand Plaschke, and Karl-Heinz Glassmeier
Ann. Geophys., 35, 117–121, https://doi.org/10.5194/angeo-35-117-2017, https://doi.org/10.5194/angeo-35-117-2017, 2017
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Vector magnetic field instruments mounted on spacecraft require precise in-flight calibration of the offsets of all three axes, i.e., the output in vanishing ambient field. While calibration of the spin plane offsets is trivial, we apply a new technique for determining the spin axis offset, not relying on solar wind data but on magnetosheath encounters. This technique is successfully applied to the satellites of the THEMIS mission to update the calibration parameters of the complete mission.
This article is included in the Encyclopedia of Geosciences
Martin Volwerk, Daniel Schmid, Bruce T. Tsurutani, Magda Delva, Ferdinand Plaschke, Yasuhito Narita, Tielong Zhang, and Karl-Heinz Glassmeier
Ann. Geophys., 34, 1099–1108, https://doi.org/10.5194/angeo-34-1099-2016, https://doi.org/10.5194/angeo-34-1099-2016, 2016
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The behaviour of mirror mode waves in Venus's magnetosheath is investigated for solar minimum and maximum conditions. It is shown that the total observational rate of these waves does not change much; however, the distribution over the magnetosheath is significantly different, as well as the growth and decay of the waves during these different solar activity conditions.
This article is included in the Encyclopedia of Geosciences
Patrick Meier, Karl-Heinz Glassmeier, and Uwe Motschmann
Ann. Geophys., 34, 691–707, https://doi.org/10.5194/angeo-34-691-2016, https://doi.org/10.5194/angeo-34-691-2016, 2016
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A new type of wave has been detected by the magnetometer of the Rosetta spacecraft close to comet P67/Churyumov-Gerasimenko. We provide the analytical model of this wave excitation from linear perturbation theory. A modified ion-Weibel instability is identified as source of this wave excited by a cometary current. The waves predominantly grow perpendicular to this current. A fan-like phase structure results from superposing the strongest growing waves in a cometary rest frame.
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Christian Nabert and Karl-Heinz Glassmeier
Ann. Geophys., 34, 421–425, https://doi.org/10.5194/angeo-34-421-2016, https://doi.org/10.5194/angeo-34-421-2016, 2016
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Electrical resistivity can influence the occurrence of shock waves. We derive analytically necessary conditions for shocks in a nonuniform resistive magnetohydrodynamic plasma. The nonuniform resistivity significantly modifies the characteristic velocity of wave propagation. A sufficient gradient of the resistivity in a diffusion region can satisfy the necessary condition for the occurrence of slow shocks, which is related to Petschek reconnection.
This article is included in the Encyclopedia of Geosciences
Dennis Frühauff and Karl-Heinz Glassmeier
Ann. Geophys., 34, 399–409, https://doi.org/10.5194/angeo-34-399-2016, https://doi.org/10.5194/angeo-34-399-2016, 2016
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This study presents an investigation on the occurrence of fast flows in the magnetotail using the complete available data set of the THEMIS spacecraft for the years 2007 to 2015. First, basic statistical findings concerning velocity distributions, occurrence rates, group structures and key features of 16 000 events are presented using Superposed Epoch and Minimum Variance Analysis techniques.
This article is included in the Encyclopedia of Geosciences
Y. Narita, E. Marsch, C. Perschke, K.-H. Glassmeier, U. Motschmann, and H. Comişel
Ann. Geophys., 34, 393–398, https://doi.org/10.5194/angeo-34-393-2016, https://doi.org/10.5194/angeo-34-393-2016, 2016
Y. Narita, R. Nakamura, W. Baumjohann, K.-H. Glassmeier, U. Motschmann, and H. Comişel
Ann. Geophys., 34, 85–89, https://doi.org/10.5194/angeo-34-85-2016, https://doi.org/10.5194/angeo-34-85-2016, 2016
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Four-spacecraft Cluster observations of turbulent fluctuations in the magnetic reconnection region in the geomagnetic tail show for the first time an indication of ion Bernstein waves, electromagnetic waves that propagate nearly perpendicular to the mean magnetic field and are in resonance with ions. Bernstein waves may influence current sheet dynamics in the reconnection outflow such as a bifurcation of the current sheet.
This article is included in the Encyclopedia of Geosciences
M. Volwerk, I. Richter, B. Tsurutani, C. Götz, K. Altwegg, T. Broiles, J. Burch, C. Carr, E. Cupido, M. Delva, M. Dósa, N. J. T. Edberg, A. Eriksson, P. Henri, C. Koenders, J.-P. Lebreton, K. E. Mandt, H. Nilsson, A. Opitz, M. Rubin, K. Schwingenschuh, G. Stenberg Wieser, K. Szegö, C. Vallat, X. Vallieres, and K.-H. Glassmeier
Ann. Geophys., 34, 1–15, https://doi.org/10.5194/angeo-34-1-2016, https://doi.org/10.5194/angeo-34-1-2016, 2016
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The solar wind magnetic field drapes around the active nucleus of comet 67P/CG, creating a magnetosphere. The solar wind density increases and with that the pressure, which compresses the magnetosphere, increasing the magnetic field strength near Rosetta. The higher solar wind density also creates more ionization through collisions with the gas from the comet. The new ions are picked-up by the magnetic field and generate mirror-mode waves, creating low-field high-density "bottles" near 67P/CG.
This article is included in the Encyclopedia of Geosciences
C. Nabert, C. Othmer, and K.-H. Glassmeier
Ann. Geophys., 33, 1513–1524, https://doi.org/10.5194/angeo-33-1513-2015, https://doi.org/10.5194/angeo-33-1513-2015, 2015
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The solar wind plasma interacts with a planetary magnetic field. A magnetohydrodynamic model is used to simulate the interaction and resulting plasma flow. The model uses solar wind inflow parameters as boundary condition. Spacecraft data of the interaction region are compared to the flow model. The solar wind boundary parameters are varied until the model matches the data. With a time-resolution of about 10min, the time-dependent solar wind boundary parameters were reconstructed from the data.
This article is included in the Encyclopedia of Geosciences
L. Dai, C. Wang, V. Angelopoulos, and K.-H. Glassmeier
Ann. Geophys., 33, 1147–1153, https://doi.org/10.5194/angeo-33-1147-2015, https://doi.org/10.5194/angeo-33-1147-2015, 2015
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Magnetic reconnection is a ubiquitous process that drives global-scale dynamics in plasmas. For reconnection to proceed, both ion and electrons must be unfrozen in a localized diffusion region. By analyzing in situ measurements, we show that the non-gyrotropic ion pressure is mainly responsible for breaking the ion frozen-in condition in reconnection. The reported non-gyrotropic ion pressure tensor can specify the reconnection electric field that controls how quickly reconnection proceeds.
This article is included in the Encyclopedia of Geosciences
I. Richter, C. Koenders, H.-U. Auster, D. Frühauff, C. Götz, P. Heinisch, C. Perschke, U. Motschmann, B. Stoll, K. Altwegg, J. Burch, C. Carr, E. Cupido, A. Eriksson, P. Henri, R. Goldstein, J.-P. Lebreton, P. Mokashi, Z. Nemeth, H. Nilsson, M. Rubin, K. Szegö, B. T. Tsurutani, C. Vallat, M. Volwerk, and K.-H. Glassmeier
Ann. Geophys., 33, 1031–1036, https://doi.org/10.5194/angeo-33-1031-2015, https://doi.org/10.5194/angeo-33-1031-2015, 2015
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We present a first report on magnetic field measurements made in the coma of comet 67P/C-G in its low-activity state. The plasma environment is dominated by quasi-coherent, large-amplitude, compressional magnetic field oscillations around 40mHz, differing from the observations at strongly active comets where waves at the cometary ion gyro-frequencies are the main feature. We propose a cross-field current instability associated with the newborn cometary ions as a possible source mechanism.
This article is included in the Encyclopedia of Geosciences
B. T. Tsurutani, R. Hajra, E. Echer, and J. W. Gjerloev
Ann. Geophys., 33, 519–524, https://doi.org/10.5194/angeo-33-519-2015, https://doi.org/10.5194/angeo-33-519-2015, 2015
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Particularly intense substorms (SSS), brilliant auroral displays with strong >106A currents in the ionosphere, are studied. It is believed that these SSS events cause power outages during magnetic storms. It is shown that SSS events can occur during all intensity magnetic storms; thus power problems are not necessarily restricted to the rare most intense storms. We show four SSS events that are triggered by solar wind pressure pulses. If this is typical, ~30-minute warnings could be issued.
This article is included in the Encyclopedia of Geosciences
M. Volwerk, K.-H. Glassmeier, M. Delva, D. Schmid, C. Koenders, I. Richter, and K. Szegö
Ann. Geophys., 32, 1441–1453, https://doi.org/10.5194/angeo-32-1441-2014, https://doi.org/10.5194/angeo-32-1441-2014, 2014
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We discuss three flybys (within an 8-day time span) of comet 1P/Halley by VEGA 1, 2 and Giotto. Looking at two different plasma phenomena: mirror mode waves and field line draping; we study the differences in SW--comet interaction between these three flybys. We find that on this time scale (comparable to Rosetta's orbits) there is a significant difference, both caused by changing outgassing rate of the comet and changes in the solar wind. We discuss implications for Rosetta RPC observations.
This article is included in the Encyclopedia of Geosciences
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
L. N. S. Alconcel, P. Fox, P. Brown, T. M. Oddy, E. L. Lucek, and C. M. Carr
Geosci. Instrum. Method. Data Syst., 3, 95–109, https://doi.org/10.5194/gi-3-95-2014, https://doi.org/10.5194/gi-3-95-2014, 2014
D. Schmid, M. Volwerk, F. Plaschke, Z. Vörös, T. L. Zhang, W. Baumjohann, and Y. Narita
Ann. Geophys., 32, 651–657, https://doi.org/10.5194/angeo-32-651-2014, https://doi.org/10.5194/angeo-32-651-2014, 2014
K.-H. Glassmeier and B. T. Tsurutani
Hist. Geo Space. Sci., 5, 11–62, https://doi.org/10.5194/hgss-5-11-2014, https://doi.org/10.5194/hgss-5-11-2014, 2014
R. Nakamura, F. Plaschke, R. Teubenbacher, L. Giner, W. Baumjohann, W. Magnes, M. Steller, R. B. Torbert, H. Vaith, M. Chutter, K.-H. Fornaçon, K.-H. Glassmeier, and C. Carr
Geosci. Instrum. Method. Data Syst., 3, 1–11, https://doi.org/10.5194/gi-3-1-2014, https://doi.org/10.5194/gi-3-1-2014, 2014
M. Volwerk, C. Koenders, M. Delva, I. Richter, K. Schwingenschuh, M. S. Bentley, and K.-H. Glassmeier
Ann. Geophys., 31, 2201–2206, https://doi.org/10.5194/angeo-31-2201-2013, https://doi.org/10.5194/angeo-31-2201-2013, 2013
C. Perschke, Y. Narita, S. P. Gary, U. Motschmann, and K.-H. Glassmeier
Ann. Geophys., 31, 1949–1955, https://doi.org/10.5194/angeo-31-1949-2013, https://doi.org/10.5194/angeo-31-1949-2013, 2013
M. A. Pudney, C. M. Carr, S. J. Schwartz, and S. I. Howarth
Geosci. Instrum. Method. Data Syst., 2, 249–255, https://doi.org/10.5194/gi-2-249-2013, https://doi.org/10.5194/gi-2-249-2013, 2013
M. Volwerk, N. André, C. S. Arridge, C. M. Jackman, X. Jia, S. E. Milan, A. Radioti, M. F. Vogt, A. P. Walsh, R. Nakamura, A. Masters, and C. Forsyth
Ann. Geophys., 31, 817–833, https://doi.org/10.5194/angeo-31-817-2013, https://doi.org/10.5194/angeo-31-817-2013, 2013
C. Nabert, K.-H. Glassmeier, and F. Plaschke
Ann. Geophys., 31, 419–437, https://doi.org/10.5194/angeo-31-419-2013, https://doi.org/10.5194/angeo-31-419-2013, 2013
B. T. Tsurutani, A. J. Mannuccci, O. P. Verkhoglyadova, and G. S. Lakhina
Ann. Geophys., 31, 145–150, https://doi.org/10.5194/angeo-31-145-2013, https://doi.org/10.5194/angeo-31-145-2013, 2013
M. Volwerk, X. Jia, C. Paranicas, W. S. Kurth, M. G. Kivelson, and K. K. Khurana
Ann. Geophys., 31, 45–59, https://doi.org/10.5194/angeo-31-45-2013, https://doi.org/10.5194/angeo-31-45-2013, 2013
A. Alexandrova, R. Nakamura, V. S. Semenov, I. V. Kubyshkin, S. Apatenkov, E. V. Panov, D. Korovinskiy, H. Biernat, W. Baumjohann, K.-H. Glassmeier, and J. P. McFadden
Ann. Geophys., 30, 1727–1741, https://doi.org/10.5194/angeo-30-1727-2012, https://doi.org/10.5194/angeo-30-1727-2012, 2012
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We have analysed the magnetic field measurements performed on the ROSETTA orbiter and the lander PHILAE during PHILAE's descent to comet 67P/Churyumov-Gerasimenko on 12 November 2014. We observed a new type of low-frequency wave with amplitudes of ~ 3 nT, frequencies of 20–50 mHz, wavelengths of ~ 300 km, and propagation velocities of ~ 6 km s−1. The waves are generated in a ~ 100 km region around the comet a show a highly correlated behaviour, which could only be determined by two-point observations.
We have analysed the magnetic field measurements performed on the ROSETTA orbiter and the lander...
