Articles | Volume 33, issue 8
https://doi.org/10.5194/angeo-33-1031-2015
© Author(s) 2015. 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-33-1031-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
ANGEO Communicates
| Highlight paper
| 
19 Aug 2015
ANGEO Communicates | Highlight paper |
| 19 Aug 2015
Observation of a new type of low-frequency waves at comet 67P/Churyumov-Gerasimenko
Institut für Geophysik und extraterrestrische Physik, TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
C. Koenders
Institut für Geophysik und extraterrestrische Physik, TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
H.-U. Auster
Institut für Geophysik und extraterrestrische Physik, TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
D. Frühauff
Institut für Geophysik und extraterrestrische Physik, TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
Institut für Geophysik und extraterrestrische Physik, TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
P. Heinisch
Institut für Geophysik und extraterrestrische Physik, TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
C. Perschke
Institut für Geophysik und extraterrestrische Physik, TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
Institut für Theoretische Physik, TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
U. Motschmann
Institut für Theoretische Physik, TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
German Aerospace Center (DLR), Institute of Planetary Research, Rutherfordstraße 2, 12489 Berlin, Germany
B. Stoll
Institut für Geophysik und extraterrestrische Physik, TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
K. Altwegg
Physikalisches Institut, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland
J. Burch
Southwest Research Institute, P.O. Drawer 28510, San Antonio, TX 78228-0510, USA
C. Carr
Imperial College London, Exhibition Road, London SW7 2AZ, UK
E. Cupido
Imperial College London, Exhibition Road, London SW7 2AZ, UK
A. Eriksson
Swedish Institute of Space Physics, Ångström Laboratory, Lägerhyddsvägen 1, Uppsala, Sweden
Laboratoire de Physique et Chimie de l'Environnement et de l'Espace, UMR 7328 CNRS – Université d'Orléans, Orléans, France
R. Goldstein
Southwest Research Institute, P.O. Drawer 28510, San Antonio, TX 78228-0510, USA
J.-P. Lebreton
Laboratoire de Physique et Chimie de l'Environnement et de l'Espace, UMR 7328 CNRS – Université d'Orléans, Orléans, France
P. Mokashi
Southwest Research Institute, P.O. Drawer 28510, San Antonio, TX 78228-0510, USA
Z. Nemeth
Wigner Research Centre for Physics, 1121 Konkoly Thege Street 29–33, Budapest, Hungary
H. Nilsson
Swedish Institute of Space Physics, P.O. Box 812, 981 28 Kiruna, Sweden
Physikalisches Institut, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland
Wigner Research Centre for Physics, 1121 Konkoly Thege Street 29–33, Budapest, Hungary
B. T. Tsurutani
Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
C. Vallat
Rosetta Science Ground Segment, European Space Astronomy Centre, 28691 Villanueva de la Cañada, Madrid, Spain
M. Volwerk
Space Research Institute, Austrian Academy of Sciences, Schmiedlstraße 6, 8042 Graz, Austria
K.-H. Glassmeier
Institut für Geophysik und extraterrestrische Physik, TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
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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.
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Ovidiu Dragoş Constantinescu, Hans-Ulrich Auster, Magda Delva, Olaf Hillenmaier, Werner Magnes, and Ferdinand Plaschke
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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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Audrey Schillings, Herbert Gunell, Hans Nilsson, Alexandre De Spiegeleer, Yusuke Ebihara, Lars G. Westerberg, Masatoshi Yamauchi, and Rikard Slapak
Ann. Geophys., 38, 645–656, https://doi.org/10.5194/angeo-38-645-2020, https://doi.org/10.5194/angeo-38-645-2020, 2020
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The Earth's atmosphere is constantly losing molecules and charged particles, amongst them oxygen ions or O+. Quantifying this loss provides information about the evolution of the atmosphere on geological timescales. In this study, we investigate the final destination of O+ observed with Cluster satellites in a high-altitude magnetospheric region (plasma mantle) by tracing the particles forward in time using simulations. We find that approximately 98 % of O+ escapes the Earth's magnetosphere.
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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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.
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.
Chen Zeng, Suping Duan, Chi Wang, Lei Dai, Stephen Fuselier, James Burch, Roy Torbert, Barbara Giles, and Christopher Russell
Ann. Geophys., 38, 123–135, https://doi.org/10.5194/angeo-38-123-2020, https://doi.org/10.5194/angeo-38-123-2020, 2020
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Oxygen ions are an important element in the mass and energy transport in the magnetospheric dynamic process during intense substorms (AE > 500 nT). We did this work to better understand the O+ at the dusk flank magnetopause varying with solar wind conditions and AE index during intense substorms. The results show the O+ abundance at the duskside magnetopause has a corresponding relation to that in the duskside near-Earth plasma sheet.
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.
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.
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.
Shiyong Huang, Pufan Zhao, Jiansen He, Zhigang Yuan, Meng Zhou, Huishan Fu, Xiaohua Deng, Ye Pang, Dedong Wang, Xiongdong Yu, Haimeng Li, Roy Torbert, and James Burch
Ann. Geophys., 36, 1275–1283, https://doi.org/10.5194/angeo-36-1275-2018, https://doi.org/10.5194/angeo-36-1275-2018, 2018
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.
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
Binbin Tang, Wenya Li, Chi Wang, Lei Dai, Yuri Khotyaintsev, Per-Arne Lindqvist, Robert Ergun, Olivier Le Contel, Craig Pollock, Christopher Russell, and James Burch
Ann. Geophys., 36, 879–889, https://doi.org/10.5194/angeo-36-879-2018, https://doi.org/10.5194/angeo-36-879-2018, 2018
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The Kelvin–Helmholtz waves are believed to be an effective way to transport solar wind mass and energy into Earth's magnetosphere. In this study, we show that the ion-scale flux rope generated at the trailing edge of Kelvin–Helmholtz waves by multiple X-line reconnection could be directly related to this transfer process. The lower hybrid drift waves detected at the edges of the flux rope can also contribute to this process and then affect the revolution of the flux rope.
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.
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.
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.
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.
Heqiucen Xu, Kazuo Shiokawa, and Dennis Frühauff
Ann. Geophys., 35, 1131–1142, https://doi.org/10.5194/angeo-35-1131-2017, https://doi.org/10.5194/angeo-35-1131-2017, 2017
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In this study, we statistically analyzed severe magnetic fluctuations in the nightside near-Earth plasma sheet. For the first time, we showed the occurrence rates of these fluctuations. The superposed epoch analysis also indicated that the flow speed increases before the severe magnetic fluctuations. We also discussed how both the inside-out and outside-in substorm models can be used to explain these observed results.
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
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.
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.
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.
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.
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.
Christina Chu, Hui Zhang, David Sibeck, Antonius Otto, QiuGang Zong, Nick Omidi, James P. McFadden, Dennis Fruehauff, and Vassilis Angelopoulos
Ann. Geophys., 35, 443–451, https://doi.org/10.5194/angeo-35-443-2017, https://doi.org/10.5194/angeo-35-443-2017, 2017
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Hot flow anomalies (HFAs) at Earth's bow shock were identified in Time History of Events and Macroscale Interactions During Substorms (THEMIS) satellite data from 2007 to 2009. The events were classified as young or mature and regular or spontaneous hot flow anomalies (SHFAs). HFA–SHFA occurrence decreases with distance upstream from the bow shock. HFAs are more prevalent for radial interplanetary magnetic fields and solar wind speeds from 550 to 600 kms−1.
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.
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.
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.
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.
Ingo Richter, Hans-Ulrich Auster, Gerhard Berghofer, Chris Carr, Emanuele Cupido, Karl-Heinz Fornaçon, Charlotte Goetz, Philip Heinisch, Christoph Koenders, Bernd Stoll, Bruce T. Tsurutani, Claire Vallat, Martin Volwerk, and Karl-Heinz Glassmeier
Ann. Geophys., 34, 609–622, https://doi.org/10.5194/angeo-34-609-2016, https://doi.org/10.5194/angeo-34-609-2016, 2016
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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.
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.
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.
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.
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.
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.
Z. Nemeth, K. Szego, L. Foldy, M. G. Kivelson, X. Jia, K. M. Ramer, S. W. H. Cowley, G. Provan, and M. Thomsen
Ann. Geophys., 33, 1195–1202, https://doi.org/10.5194/angeo-33-1195-2015, https://doi.org/10.5194/angeo-33-1195-2015, 2015
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The latitudinal structure of the nightside outer magnetosphere of Saturn was studied by using Cassini CAPS plasma measurements. It was found that the plasma density and the azimuthal velocity decrease simultaneously as the spacecraft moves away from the magnetic equator. The magnetosphere exhibits an “onion shell like” structure: the inner regions spin rapidly corotating with the planet, but moving outward and/or further away from the equatorial plane one can encounter slower and slower shells.
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.
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.
H. Comişel, Y. Narita, and U. Motschmann
Ann. Geophys., 33, 345–350, https://doi.org/10.5194/angeo-33-345-2015, https://doi.org/10.5194/angeo-33-345-2015, 2015
R. Slapak, H. Nilsson, L. G. Westerberg, and R. Larsson
Ann. Geophys., 33, 301–307, https://doi.org/10.5194/angeo-33-301-2015, https://doi.org/10.5194/angeo-33-301-2015, 2015
T. Pitkänen, M. Hamrin, P. Norqvist, T. Karlsson, H. Nilsson, A. Kullen, S. M. Imber, and S. E. Milan
Ann. Geophys., 33, 245–255, https://doi.org/10.5194/angeo-33-245-2015, https://doi.org/10.5194/angeo-33-245-2015, 2015
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An azimuthal velocity shear with a reversal within an earthward magnetotail fast flow is studied using Cluster observations. In addition, ionospheric SuperDARN data and different magnetospheric models (T96 and TF04) are utilized when interpreting the Cluster observations. Untwisting of twisted tail B field lines is a good candidate to explain the observations.
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.
H. Comişel, Y. Narita, and U. Motschmann
Nonlin. Processes Geophys., 21, 1075–1083, https://doi.org/10.5194/npg-21-1075-2014, https://doi.org/10.5194/npg-21-1075-2014, 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
Y. V. Khotyaintsev, P.-A. Lindqvist, C. M. Cully, A. I. Eriksson, and M. André
Geosci. Instrum. Method. Data Syst., 3, 143–151, https://doi.org/10.5194/gi-3-143-2014, https://doi.org/10.5194/gi-3-143-2014, 2014
I. A. Barghouthi, H. Nilsson, and S. H. Ghithan
Ann. Geophys., 32, 1043–1057, https://doi.org/10.5194/angeo-32-1043-2014, https://doi.org/10.5194/angeo-32-1043-2014, 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. Axelsson, T. Sergienko, H. Nilsson, U. Brändström, K. Asamura, and T. Sakanoi
Ann. Geophys., 32, 499–506, https://doi.org/10.5194/angeo-32-499-2014, https://doi.org/10.5194/angeo-32-499-2014, 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
C. Béghin, G. Wattieaux, R. Grard, M. Hamelin, and J. P. Lebreton
Geosci. Instrum. Method. Data Syst., 2, 237–248, https://doi.org/10.5194/gi-2-237-2013, https://doi.org/10.5194/gi-2-237-2013, 2013
R. Slapak, H. Nilsson, and L. G. Westerberg
Ann. Geophys., 31, 1005–1010, https://doi.org/10.5194/angeo-31-1005-2013, https://doi.org/10.5194/angeo-31-1005-2013, 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
S. Kirkwood, E. Belova, P. Dalin, M. Mihalikova, D. Mikhaylova, D. Murtagh, H. Nilsson, K. Satheesan, J. Urban, and I. Wolf
Ann. Geophys., 31, 333–347, https://doi.org/10.5194/angeo-31-333-2013, https://doi.org/10.5194/angeo-31-333-2013, 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
K. Axelsson, T. Sergienko, H. Nilsson, U. Brändström, Y. Ebihara, K. Asamura, and M. Hirahara
Ann. Geophys., 30, 1693–1701, https://doi.org/10.5194/angeo-30-1693-2012, https://doi.org/10.5194/angeo-30-1693-2012, 2012
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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.
We present a first report on magnetic field measurements made in the coma of comet 67P/C-G in...
