Articles | Volume 34, issue 4
https://doi.org/10.5194/angeo-34-393-2016
© 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-34-393-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
ANGEO Communicates
| 
07 Apr 2016
ANGEO Communicates |
| 07 Apr 2016
Wave–particle resonance condition test for ion-kinetic waves in the solar wind
Space Research Institute, Austrian Academy of Sciences,
Schmiedlstr. 6, 8042 Graz, Austria
Institut für Geophysik und extraterrestrische Physik,
Technische Universität Braunschweig, Mendelssohnstr. 3,
38106 Braunschweig, Germany
E. Marsch
Institut für Experimentelle und Angewandte Physik,
Christian-Albrechts Universität Kiel, Leibnizstr. 11, 24118 Kiel, Germany
C. Perschke
Institut für Geophysik und extraterrestrische Physik,
Technische Universität Braunschweig, Mendelssohnstr. 3,
38106 Braunschweig, Germany
Institut für Theoretische Physik, Technische Universität Braunschweig,
Mendelssohnstr. 3, 38106 Braunschweig, Germany
K.-H. Glassmeier
Institut für Geophysik und extraterrestrische Physik,
Technische Universität Braunschweig, Mendelssohnstr. 3,
38106 Braunschweig, Germany
Max-Planck-Institut für Sonnensystemforschung,
Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
U. Motschmann
Institut für Theoretische Physik, Technische Universität Braunschweig,
Mendelssohnstr. 3, 38106 Braunschweig, Germany
Deutsches Zentrum für Luft- und Raumfahrt, Institut für
Planetenforschung, Rutherfordstr. 2, 12489 Berlin, Germany
H. Comişel
Institut für Theoretische Physik, Technische Universität Braunschweig,
Mendelssohnstr. 3, 38106 Braunschweig, Germany
Institute for Space Sciences, Atomiştilor 409, P.O. Box MG-23,
Bucharest-Măgurele, 077125, Romania
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Yasuhito Narita, Daniel Schmid, and Uwe Motschmann
EGUsphere, https://doi.org/10.5194/egusphere-2025-60, https://doi.org/10.5194/egusphere-2025-60, 2025
This preprint is open for discussion and under review for Annales Geophysicae (ANGEO).
Short summary
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It is often the case that only magnetic field data are available in in-situ planetary studies using spacecraft. Plasma data are either not available or the amount is highly limited. Nevertheless, the theory of plasma instability tells us how to interpret the magnetic field data (wave frequency) in terms of flow speed and beam velocity generating the instability. We invent an analysis tool for the Mercury upstream waves as example.
Yasuhito Narita, Daniel Schmid, and Simon Toepfer
Ann. Geophys., 42, 79–89, https://doi.org/10.5194/angeo-42-79-2024, https://doi.org/10.5194/angeo-42-79-2024, 2024
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The magnetosheath is a transition layer surrounding the planetary magnetosphere. We develop an algorithm to compute the plasma flow velocity and magnetic field for a more general shape of magnetosheath using the concept of potential field and suitable coordinate transformation. Application to the empirical Earth magnetosheath region is shown in the paper. The developed algorithm is useful when interpreting the spacecraft data or simulation of the planetary magnetosheath region.
Yasuhito Narita, Simon Toepfer, and Daniel Schmid
Ann. Geophys., 41, 87–91, https://doi.org/10.5194/angeo-41-87-2023, https://doi.org/10.5194/angeo-41-87-2023, 2023
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Magnetopause is a shielding boundary of planetary magnetic field. Many mathematical models have been proposed to describe or to reproduce the magnetopause location, but they are restricted to the real-number functions. In this work, we analytically develop a magnetopause model in the complex-number domain, which is advantageous in deforming the magnetopause shape in a conformal (angle-preserving) way, and is suited to compare different models or map one model onto another.
Daniel Schmid and Yasuhito Narita
Ann. Geophys. Discuss., https://doi.org/10.5194/angeo-2022-30, https://doi.org/10.5194/angeo-2022-30, 2023
Revised manuscript not accepted
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Here we present a useful tool to diagnose the bow shock condition around planets on basis of magnetic field observations. From the upstream and downstream shock normal angle of the magnetic field, it is possible to approximate the relation between compression ratio, Alfvenic Mach number and the solar wind plasma beta. The tool is particularly helpful to study the solar wind conditions and bow shock characteristics during the planetary flybys of the ongoing BepiColombo mission.
Simon Toepfer, Ida Oertel, Vanita Schiron, Yasuhito Narita, Karl-Heinz Glassmeier, Daniel Heyner, Patrick Kolhey, and Uwe Motschmann
Ann. Geophys., 40, 91–105, https://doi.org/10.5194/angeo-40-91-2022, https://doi.org/10.5194/angeo-40-91-2022, 2022
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Revealing the nature of Mercury’s internal magnetic field is one of the primary goals of the BepiColombo mission. Besides the parametrization of the magnetic field contributions, the application of a robust inversion method is of major importance. The present work provides an overview of the most commonly used inversion methods and shows that Capon’s method as well as the Tikhonov regularization enable a high-precision determination of Mercury’s internal magnetic field up to the fifth degree.
Yasuhito Narita
Ann. Geophys., 39, 759–768, https://doi.org/10.5194/angeo-39-759-2021, https://doi.org/10.5194/angeo-39-759-2021, 2021
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Short summary
The concept of electromotive force appears in various electromagnetic applications in geophysical and astrophysical fluid studies. The electromotive force is being recognized as a useful tool to construct a more complete picture of turbulent space plasma and has the potential to test for the fundamental processes of dynamo mechanism in space.
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.
Horia Comişel, Yasuhito Narita, and Uwe Motschmann
Ann. Geophys., 39, 165–170, https://doi.org/10.5194/angeo-39-165-2021, https://doi.org/10.5194/angeo-39-165-2021, 2021
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Identification of a large-amplitude Alfvén wave decaying into a pair of
ion-acoustic and daughter Alfvén waves is one of the major goals in the
observational studies of space plasma nonlinearity.
Growth-rate maps
may serve as a useful tool for predictions of the wavevector spectrum of density
or magnetic field fluctuations in various scenarios for the
wave–wave coupling processes developing at different stages in
space plasma turbulence.
Yasuhito Narita, Ferdinand Plaschke, Werner Magnes, David Fischer, and Daniel Schmid
Geosci. Instrum. Method. Data Syst., 10, 13–24, https://doi.org/10.5194/gi-10-13-2021, https://doi.org/10.5194/gi-10-13-2021, 2021
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The systematic error of calibrated fluxgate magnetometer data is studied for a spinning spacecraft. The major error comes from the offset uncertainty when the ambient magnetic field is low, while the error represents the combination of non-orthogonality, misalignment to spacecraft reference direction, and gain when the ambient field is high. The results are useful in developing future high-precision magnetometers and an error estimate in scientific studies using magnetometer data.
Simon Toepfer, Yasuhito Narita, Daniel Heyner, Patrick Kolhey, and Uwe Motschmann
Geosci. Instrum. Method. Data Syst., 9, 471–481, https://doi.org/10.5194/gi-9-471-2020, https://doi.org/10.5194/gi-9-471-2020, 2020
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The Capon method serves as a powerful and robust data analysis tool when working on various kinds of ill-posed inverse problems. Besides the analysis of waves, the method can be used in a generalized way to compare actual measurements with theoretical models, such as Mercury's magnetic field analysis. In view to the BepiColombo mission this work establishes a mathematical basis for the application of Capon's method to analyze Mercury's internal magnetic field in a robust and manageable way.
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.
Horia Comişel, Yasuhito Narita, and Uwe Motschmann
Ann. Geophys., 37, 835–842, https://doi.org/10.5194/angeo-37-835-2019, https://doi.org/10.5194/angeo-37-835-2019, 2019
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Here we present a scenario that the decay of a field-aligned Alfvén wave can occur simultaneously at various angles to the mean magnetic field, generating a number of second-order fluctuations or waves (after the pump wave as the first-order fluctuation). We refer to the simultaneous decay as
multi-channel couplingsfollowing the notion in scattering theory. Our goal is to study the hypothesis of the multi-channel coupling by running a three-dimensional hybrid plasma simulation.
Yasuhito Narita, Wolfgang Baumjohann, and Rudolf A. Treumann
Ann. Geophys., 37, 825–834, https://doi.org/10.5194/angeo-37-825-2019, https://doi.org/10.5194/angeo-37-825-2019, 2019
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Scaling laws and energy spectra for the electric field, magnetic field, flow velocity, and density are theoretically derived for small-scale turbulence in space plasma on which the electrons behave as a fluid but the ions more as individual particles due to the difference in the mass (the Hall effect). Our theoretical model offers an explanation for the small-scale turbulence spectra measured in near-Earth space.
Christoph Lhotka and Yasuhito Narita
Ann. Geophys., 37, 299–314, https://doi.org/10.5194/angeo-37-299-2019, https://doi.org/10.5194/angeo-37-299-2019, 2019
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The interplanetary magnetic field is a consequence of the solar magnetic field and the solar wind. Different magnetic field models exist in literature that allow us to better understand how the solar field extends throughout the solar system. We highlight different aspects of these different interplanetary magnetic field models and discuss possible applications. Verification of these models will become possible using data from the Parker Solar Probe and BepiColombo space mission.
Rudolf A. Treumann, Wolfgang Baumjohann, and Yasuhito Narita
Ann. Geophys., 37, 183–199, https://doi.org/10.5194/angeo-37-183-2019, https://doi.org/10.5194/angeo-37-183-2019, 2019
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Occasional deviations in density and magnetic power spectral densities in an intermediate frequency range are interpreted as an ion-inertial-range response to either the Kolmogorov or Iroshnikov–Kraichnan inertial-range turbulent velocity spectrum.
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.
Horia Comişel, Yasuhiro Nariyuki, Yasuhito Narita, and Uwe Motschmann
Ann. Geophys., 36, 1647–1655, https://doi.org/10.5194/angeo-36-1647-2018, https://doi.org/10.5194/angeo-36-1647-2018, 2018
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Space plasmas are assumed to be highly active and dynamic systems including waves and turbulence. Electromagnetic waves such as Alfven waves interact with one another, producing daughter waves. In our study based on three-dimensional hybrid simulations, we emphasize the role of obliquely propagating daughter waves in particle heating in low-temperature (or low-beta) plasmas. The evolutions of plasma turbulence, wave dissipation, and heating are essential problems in astrophysics.
Yasuhito Narita and Uwe Motschmann
Ann. Geophys., 36, 1537–1543, https://doi.org/10.5194/angeo-36-1537-2018, https://doi.org/10.5194/angeo-36-1537-2018, 2018
Short summary
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Venus has no intrinsic magnetic field. On the other hand, we discover that an interplanetary magnetic field may nevertheless penetrate the planetary ionosphere by the diffusion process and reach the planetary surface when the solar wind condition remains for a sufficiently long time, between 12 and 54 h, depending on the condition of ionosphere.
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
Owen W. Roberts, Yasuhito Narita, and C.-Philippe Escoubet
Ann. Geophys., 36, 527–539, https://doi.org/10.5194/angeo-36-527-2018, https://doi.org/10.5194/angeo-36-527-2018, 2018
Short summary
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In this study we use multi-point spacecraft measurements of magnetic field and electron density derived from spacecraft potential to investigate the three-dimensional structure of solar wind plasma turbulence. We see that there is a dependence on the plasma beta (ratio of thermal to magnetic pressure) as well as a dependence on the type of wind i.e. fast or slow.
Yasuhito Narita and Zoltán Vörös
Ann. Geophys., 36, 101–106, https://doi.org/10.5194/angeo-36-101-2018, https://doi.org/10.5194/angeo-36-101-2018, 2018
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Electromotive force plays a central role in the dynamo mechanism amplifying the magnetic field in turbulent plasmas and electrically conducting fluids. An algorithm is developed to measure the electromotive force using spacecraft data, and it is applied to a magnetic cloud event in interplanetary space. The electromotive force is enhanced when the magnetic cloud passes by the spacecraft, indicating local amplification of the magnetic field.
Owen W. Roberts, Yasuhito Narita, and C.-Philippe Escoubet
Ann. Geophys., 36, 47–52, https://doi.org/10.5194/angeo-36-47-2018, https://doi.org/10.5194/angeo-36-47-2018, 2018
Short summary
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To investigate compressible plasma turbulence in the solar wind on proton kinetic scales, a high time resolution measurement of the density is obtained from the spacecraft potential. Correlation between the magnetic field strength and the density is investigated as is the rotation sense of the magnetic field. The analysis reveals that compressible fluctuations are characteristic of kinetic Alfvén waves or a mixture of kinetic Alfvén and kinetic slow waves which counter-propagate.
Yasuhito Narita and Zoltán Vörös
Nonlin. Processes Geophys., 24, 673–679, https://doi.org/10.5194/npg-24-673-2017, https://doi.org/10.5194/npg-24-673-2017, 2017
Short summary
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A method is proposed to determine the temporal decay rate of turbulent fluctuations, and is applied to four-point magnetic field data in interplanetary space. The measured decay, interpreted as the energy transfer rate in turbulence, is larger than the theoretical estimate from the fluid turbulence theory. The faster decay represents one of the differences in turbulent processes between fluid and plasma media.
Yasuhito Narita
Nonlin. Processes Geophys., 24, 203–214, https://doi.org/10.5194/npg-24-203-2017, https://doi.org/10.5194/npg-24-203-2017, 2017
Short summary
Short summary
Various methods in the single-spacecraft data analysis are reviewed to determine physical properties of waves, turbulent fluctuations, and wave-wave and wave-particle interactions in the space plasma environment using the magnetic field, the electric field, and the plasma data.
Yasuhito Narita, Yoshihiro Nishimura, and Tohru Hada
Ann. Geophys., 35, 639–644, https://doi.org/10.5194/angeo-35-639-2017, https://doi.org/10.5194/angeo-35-639-2017, 2017
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An algorithm is proposed to estimate the spectral index of the turbulence energy spectrum directly in the wavenumber domain using multiple-sensor-array data. In contrast to the conventional method using time series data and Fourier transform of the fluctuation energy onto the frequency domain, the proposed algorithm does not require the assumption of Taylor's frozen inflow hypothesis, enabling direct comparison of the spectra in the wavenumber domain with various theoretical predictions.
Yasuhito Narita
Ann. Geophys., 35, 325–331, https://doi.org/10.5194/angeo-35-325-2017, https://doi.org/10.5194/angeo-35-325-2017, 2017
Short summary
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In situ spacecraft data in space plasma are obtained often as time series data. Using Taylor's frozen-in flow hypothesis, one can interpret the time series data as spatial variations swept by the slow and passing by the spacecraft. A quantitative method for estimating the error for Taylor's hypothesis is developed here.
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.
Horia Comişel, Yasuhiro Nariyuki, Yasuhito Narita, and Uwe Motschmann
Ann. Geophys., 34, 975–984, https://doi.org/10.5194/angeo-34-975-2016, https://doi.org/10.5194/angeo-34-975-2016, 2016
Ferdinand Plaschke and Yasuhito Narita
Ann. Geophys., 34, 759–766, https://doi.org/10.5194/angeo-34-759-2016, https://doi.org/10.5194/angeo-34-759-2016, 2016
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Spacecraft-mounted magnetic field instruments (magnetometers) need to be routinely calibrated. This involves determining the magnetometer outputs in vanishing ambient magnetic fields, the so-called offsets. We introduce and test a new method to determine these offsets with high accuracy, the mirror mode method, which is complementary to existing methods. The mirror mode method should be highly beneficial to current and future magnetic field observations near Earth, other planets, and comets.
Rudolf A. Treumann, Wolfgang Baumjohann, and Yasuhito Narita
Ann. Geophys., 34, 673–689, https://doi.org/10.5194/angeo-34-673-2016, https://doi.org/10.5194/angeo-34-673-2016, 2016
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In support of low-frequency electromagnetic turbulence we formulate the inverse scattering theory of electromagnetic fluctuations in plasma. Its solution provides the turbulent response function which contains all information of the dynamical causes of the electromagnetic fluctuations. This is of basic interest in any electromagnetic turbulence. It requires measurement of magnetic and electric fluctuations but makes no direct use of the turbulent power spectral density.
Y. Narita, H. Comişel, and U. Motschmann
Ann. Geophys., 34, 591–593, https://doi.org/10.5194/angeo-34-591-2016, https://doi.org/10.5194/angeo-34-591-2016, 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.
Y. Narita
Ann. Geophys., 33, 1413–1419, https://doi.org/10.5194/angeo-33-1413-2015, https://doi.org/10.5194/angeo-33-1413-2015, 2015
Short summary
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A lot of efforts have been put into understanding the turbulence structure in space and astrophysical plasmas, in particular how the filamentary structure develops as the length scale of the turbulent fluctuations changes from large to smaller ones. Motivated by the recent spacecraft observations in the solar wind, an analytic model is proposed to explain the nature of filament-formation processes in space plasma turbulence with a successful test against the spacecraft observations.
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
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
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
M. Wilczek, H. Xu, and Y. Narita
Nonlin. Processes Geophys., 21, 645–649, https://doi.org/10.5194/npg-21-645-2014, https://doi.org/10.5194/npg-21-645-2014, 2014
Y. Narita
Nonlin. Processes Geophys., 21, 41–47, https://doi.org/10.5194/npg-21-41-2014, https://doi.org/10.5194/npg-21-41-2014, 2014
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
Y. Narita, R. Nakamura, and W. Baumjohann
Ann. Geophys., 31, 1605–1610, https://doi.org/10.5194/angeo-31-1605-2013, https://doi.org/10.5194/angeo-31-1605-2013, 2013
Yasuhito Narita, Daniel Schmid, and Uwe Motschmann
EGUsphere, https://doi.org/10.5194/egusphere-2025-60, https://doi.org/10.5194/egusphere-2025-60, 2025
This preprint is open for discussion and under review for Annales Geophysicae (ANGEO).
Short summary
Short summary
It is often the case that only magnetic field data are available in in-situ planetary studies using spacecraft. Plasma data are either not available or the amount is highly limited. Nevertheless, the theory of plasma instability tells us how to interpret the magnetic field data (wave frequency) in terms of flow speed and beam velocity generating the instability. We invent an analysis tool for the Mercury upstream waves as example.
Yasuhito Narita, Daniel Schmid, and Simon Toepfer
Ann. Geophys., 42, 79–89, https://doi.org/10.5194/angeo-42-79-2024, https://doi.org/10.5194/angeo-42-79-2024, 2024
Short summary
Short summary
The magnetosheath is a transition layer surrounding the planetary magnetosphere. We develop an algorithm to compute the plasma flow velocity and magnetic field for a more general shape of magnetosheath using the concept of potential field and suitable coordinate transformation. Application to the empirical Earth magnetosheath region is shown in the paper. The developed algorithm is useful when interpreting the spacecraft data or simulation of the planetary magnetosheath region.
Yasuhito Narita, Simon Toepfer, and Daniel Schmid
Ann. Geophys., 41, 87–91, https://doi.org/10.5194/angeo-41-87-2023, https://doi.org/10.5194/angeo-41-87-2023, 2023
Short summary
Short summary
Magnetopause is a shielding boundary of planetary magnetic field. Many mathematical models have been proposed to describe or to reproduce the magnetopause location, but they are restricted to the real-number functions. In this work, we analytically develop a magnetopause model in the complex-number domain, which is advantageous in deforming the magnetopause shape in a conformal (angle-preserving) way, and is suited to compare different models or map one model onto another.
Daniel Schmid and Yasuhito Narita
Ann. Geophys. Discuss., https://doi.org/10.5194/angeo-2022-30, https://doi.org/10.5194/angeo-2022-30, 2023
Revised manuscript not accepted
Short summary
Short summary
Here we present a useful tool to diagnose the bow shock condition around planets on basis of magnetic field observations. From the upstream and downstream shock normal angle of the magnetic field, it is possible to approximate the relation between compression ratio, Alfvenic Mach number and the solar wind plasma beta. The tool is particularly helpful to study the solar wind conditions and bow shock characteristics during the planetary flybys of the ongoing BepiColombo mission.
Simon Toepfer, Ida Oertel, Vanita Schiron, Yasuhito Narita, Karl-Heinz Glassmeier, Daniel Heyner, Patrick Kolhey, and Uwe Motschmann
Ann. Geophys., 40, 91–105, https://doi.org/10.5194/angeo-40-91-2022, https://doi.org/10.5194/angeo-40-91-2022, 2022
Short summary
Short summary
Revealing the nature of Mercury’s internal magnetic field is one of the primary goals of the BepiColombo mission. Besides the parametrization of the magnetic field contributions, the application of a robust inversion method is of major importance. The present work provides an overview of the most commonly used inversion methods and shows that Capon’s method as well as the Tikhonov regularization enable a high-precision determination of Mercury’s internal magnetic field up to the fifth degree.
Yasuhito Narita
Ann. Geophys., 39, 759–768, https://doi.org/10.5194/angeo-39-759-2021, https://doi.org/10.5194/angeo-39-759-2021, 2021
Short summary
Short summary
The concept of electromotive force appears in various electromagnetic applications in geophysical and astrophysical fluid studies. The electromotive force is being recognized as a useful tool to construct a more complete picture of turbulent space plasma and has the potential to test for the fundamental processes of dynamo mechanism in space.
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.
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
Short summary
Short summary
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.
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.
Horia Comişel, Yasuhito Narita, and Uwe Motschmann
Ann. Geophys., 39, 165–170, https://doi.org/10.5194/angeo-39-165-2021, https://doi.org/10.5194/angeo-39-165-2021, 2021
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Identification of a large-amplitude Alfvén wave decaying into a pair of
ion-acoustic and daughter Alfvén waves is one of the major goals in the
observational studies of space plasma nonlinearity.
Growth-rate maps
may serve as a useful tool for predictions of the wavevector spectrum of density
or magnetic field fluctuations in various scenarios for the
wave–wave coupling processes developing at different stages in
space plasma turbulence.
Yasuhito Narita, Ferdinand Plaschke, Werner Magnes, David Fischer, and Daniel Schmid
Geosci. Instrum. Method. Data Syst., 10, 13–24, https://doi.org/10.5194/gi-10-13-2021, https://doi.org/10.5194/gi-10-13-2021, 2021
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The systematic error of calibrated fluxgate magnetometer data is studied for a spinning spacecraft. The major error comes from the offset uncertainty when the ambient magnetic field is low, while the error represents the combination of non-orthogonality, misalignment to spacecraft reference direction, and gain when the ambient field is high. The results are useful in developing future high-precision magnetometers and an error estimate in scientific studies using magnetometer data.
Simon Toepfer, Yasuhito Narita, Daniel Heyner, Patrick Kolhey, and Uwe Motschmann
Geosci. Instrum. Method. Data Syst., 9, 471–481, https://doi.org/10.5194/gi-9-471-2020, https://doi.org/10.5194/gi-9-471-2020, 2020
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The Capon method serves as a powerful and robust data analysis tool when working on various kinds of ill-posed inverse problems. Besides the analysis of waves, the method can be used in a generalized way to compare actual measurements with theoretical models, such as Mercury's magnetic field analysis. In view to the BepiColombo mission this work establishes a mathematical basis for the application of Capon's method to analyze Mercury's internal magnetic field in a robust and manageable way.
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.
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.
Horia Comişel, Yasuhito Narita, and Uwe Motschmann
Ann. Geophys., 37, 835–842, https://doi.org/10.5194/angeo-37-835-2019, https://doi.org/10.5194/angeo-37-835-2019, 2019
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Here we present a scenario that the decay of a field-aligned Alfvén wave can occur simultaneously at various angles to the mean magnetic field, generating a number of second-order fluctuations or waves (after the pump wave as the first-order fluctuation). We refer to the simultaneous decay as
multi-channel couplingsfollowing the notion in scattering theory. Our goal is to study the hypothesis of the multi-channel coupling by running a three-dimensional hybrid plasma simulation.
Yasuhito Narita, Wolfgang Baumjohann, and Rudolf A. Treumann
Ann. Geophys., 37, 825–834, https://doi.org/10.5194/angeo-37-825-2019, https://doi.org/10.5194/angeo-37-825-2019, 2019
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Scaling laws and energy spectra for the electric field, magnetic field, flow velocity, and density are theoretically derived for small-scale turbulence in space plasma on which the electrons behave as a fluid but the ions more as individual particles due to the difference in the mass (the Hall effect). Our theoretical model offers an explanation for the small-scale turbulence spectra measured in near-Earth space.
Christoph Lhotka and Yasuhito Narita
Ann. Geophys., 37, 299–314, https://doi.org/10.5194/angeo-37-299-2019, https://doi.org/10.5194/angeo-37-299-2019, 2019
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The interplanetary magnetic field is a consequence of the solar magnetic field and the solar wind. Different magnetic field models exist in literature that allow us to better understand how the solar field extends throughout the solar system. We highlight different aspects of these different interplanetary magnetic field models and discuss possible applications. Verification of these models will become possible using data from the Parker Solar Probe and BepiColombo space mission.
Rudolf A. Treumann, Wolfgang Baumjohann, and Yasuhito Narita
Ann. Geophys., 37, 183–199, https://doi.org/10.5194/angeo-37-183-2019, https://doi.org/10.5194/angeo-37-183-2019, 2019
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Occasional deviations in density and magnetic power spectral densities in an intermediate frequency range are interpreted as an ion-inertial-range response to either the Kolmogorov or Iroshnikov–Kraichnan inertial-range turbulent velocity spectrum.
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.
Horia Comişel, Yasuhiro Nariyuki, Yasuhito Narita, and Uwe Motschmann
Ann. Geophys., 36, 1647–1655, https://doi.org/10.5194/angeo-36-1647-2018, https://doi.org/10.5194/angeo-36-1647-2018, 2018
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Space plasmas are assumed to be highly active and dynamic systems including waves and turbulence. Electromagnetic waves such as Alfven waves interact with one another, producing daughter waves. In our study based on three-dimensional hybrid simulations, we emphasize the role of obliquely propagating daughter waves in particle heating in low-temperature (or low-beta) plasmas. The evolutions of plasma turbulence, wave dissipation, and heating are essential problems in astrophysics.
Eckart Marsch
Ann. Geophys., 36, 1607–1630, https://doi.org/10.5194/angeo-36-1607-2018, https://doi.org/10.5194/angeo-36-1607-2018, 2018
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This paper originated from the lecture I gave as the Hannes Alfvén medalist at the EGU General Assembly in Vienna in spring 2018. The paper
reviews various aspects of modern solar wind physics and elucidates the role Alfvén waves play in solar wind acceleration and turbulence, which prevail in the low
corona and inner heliosphere. Our understanding of the solar wind has recently made considerable progress based on remote sensing, in situ measurements, kinetic
simulation and fluid modeling.
Yasuhito Narita and Uwe Motschmann
Ann. Geophys., 36, 1537–1543, https://doi.org/10.5194/angeo-36-1537-2018, https://doi.org/10.5194/angeo-36-1537-2018, 2018
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Venus has no intrinsic magnetic field. On the other hand, we discover that an interplanetary magnetic field may nevertheless penetrate the planetary ionosphere by the diffusion process and reach the planetary surface when the solar wind condition remains for a sufficiently long time, between 12 and 54 h, depending on the condition of ionosphere.
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
Owen W. Roberts, Yasuhito Narita, and C.-Philippe Escoubet
Ann. Geophys., 36, 527–539, https://doi.org/10.5194/angeo-36-527-2018, https://doi.org/10.5194/angeo-36-527-2018, 2018
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In this study we use multi-point spacecraft measurements of magnetic field and electron density derived from spacecraft potential to investigate the three-dimensional structure of solar wind plasma turbulence. We see that there is a dependence on the plasma beta (ratio of thermal to magnetic pressure) as well as a dependence on the type of wind i.e. fast or slow.
Yasuhito Narita and Zoltán Vörös
Ann. Geophys., 36, 101–106, https://doi.org/10.5194/angeo-36-101-2018, https://doi.org/10.5194/angeo-36-101-2018, 2018
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Electromotive force plays a central role in the dynamo mechanism amplifying the magnetic field in turbulent plasmas and electrically conducting fluids. An algorithm is developed to measure the electromotive force using spacecraft data, and it is applied to a magnetic cloud event in interplanetary space. The electromotive force is enhanced when the magnetic cloud passes by the spacecraft, indicating local amplification of the magnetic field.
Owen W. Roberts, Yasuhito Narita, and C.-Philippe Escoubet
Ann. Geophys., 36, 47–52, https://doi.org/10.5194/angeo-36-47-2018, https://doi.org/10.5194/angeo-36-47-2018, 2018
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To investigate compressible plasma turbulence in the solar wind on proton kinetic scales, a high time resolution measurement of the density is obtained from the spacecraft potential. Correlation between the magnetic field strength and the density is investigated as is the rotation sense of the magnetic field. The analysis reveals that compressible fluctuations are characteristic of kinetic Alfvén waves or a mixture of kinetic Alfvén and kinetic slow waves which counter-propagate.
Yasuhito Narita and Zoltán Vörös
Nonlin. Processes Geophys., 24, 673–679, https://doi.org/10.5194/npg-24-673-2017, https://doi.org/10.5194/npg-24-673-2017, 2017
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A method is proposed to determine the temporal decay rate of turbulent fluctuations, and is applied to four-point magnetic field data in interplanetary space. The measured decay, interpreted as the energy transfer rate in turbulence, is larger than the theoretical estimate from the fluid turbulence theory. The faster decay represents one of the differences in turbulent processes between fluid and plasma media.
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.
Yasuhito Narita
Nonlin. Processes Geophys., 24, 203–214, https://doi.org/10.5194/npg-24-203-2017, https://doi.org/10.5194/npg-24-203-2017, 2017
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Various methods in the single-spacecraft data analysis are reviewed to determine physical properties of waves, turbulent fluctuations, and wave-wave and wave-particle interactions in the space plasma environment using the magnetic field, the electric field, and the plasma data.
Yasuhito Narita, Yoshihiro Nishimura, and Tohru Hada
Ann. Geophys., 35, 639–644, https://doi.org/10.5194/angeo-35-639-2017, https://doi.org/10.5194/angeo-35-639-2017, 2017
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An algorithm is proposed to estimate the spectral index of the turbulence energy spectrum directly in the wavenumber domain using multiple-sensor-array data. In contrast to the conventional method using time series data and Fourier transform of the fluctuation energy onto the frequency domain, the proposed algorithm does not require the assumption of Taylor's frozen inflow hypothesis, enabling direct comparison of the spectra in the wavenumber domain with various theoretical predictions.
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.
Yasuhito Narita
Ann. Geophys., 35, 325–331, https://doi.org/10.5194/angeo-35-325-2017, https://doi.org/10.5194/angeo-35-325-2017, 2017
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In situ spacecraft data in space plasma are obtained often as time series data. Using Taylor's frozen-in flow hypothesis, one can interpret the time series data as spatial variations swept by the slow and passing by the spacecraft. A quantitative method for estimating the error for Taylor's hypothesis is developed here.
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.
Horia Comişel, Yasuhiro Nariyuki, Yasuhito Narita, and Uwe Motschmann
Ann. Geophys., 34, 975–984, https://doi.org/10.5194/angeo-34-975-2016, https://doi.org/10.5194/angeo-34-975-2016, 2016
Ferdinand Plaschke and Yasuhito Narita
Ann. Geophys., 34, 759–766, https://doi.org/10.5194/angeo-34-759-2016, https://doi.org/10.5194/angeo-34-759-2016, 2016
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Spacecraft-mounted magnetic field instruments (magnetometers) need to be routinely calibrated. This involves determining the magnetometer outputs in vanishing ambient magnetic fields, the so-called offsets. We introduce and test a new method to determine these offsets with high accuracy, the mirror mode method, which is complementary to existing methods. The mirror mode method should be highly beneficial to current and future magnetic field observations near Earth, other planets, and comets.
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.
Rudolf A. Treumann, Wolfgang Baumjohann, and Yasuhito Narita
Ann. Geophys., 34, 673–689, https://doi.org/10.5194/angeo-34-673-2016, https://doi.org/10.5194/angeo-34-673-2016, 2016
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In support of low-frequency electromagnetic turbulence we formulate the inverse scattering theory of electromagnetic fluctuations in plasma. Its solution provides the turbulent response function which contains all information of the dynamical causes of the electromagnetic fluctuations. This is of basic interest in any electromagnetic turbulence. It requires measurement of magnetic and electric fluctuations but makes no direct use of the turbulent power spectral density.
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.
Y. Narita, H. Comişel, and U. Motschmann
Ann. Geophys., 34, 591–593, https://doi.org/10.5194/angeo-34-591-2016, https://doi.org/10.5194/angeo-34-591-2016, 2016
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, 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.
Y. Narita
Ann. Geophys., 33, 1413–1419, https://doi.org/10.5194/angeo-33-1413-2015, https://doi.org/10.5194/angeo-33-1413-2015, 2015
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A lot of efforts have been put into understanding the turbulence structure in space and astrophysical plasmas, in particular how the filamentary structure develops as the length scale of the turbulent fluctuations changes from large to smaller ones. Motivated by the recent spacecraft observations in the solar wind, an analytic model is proposed to explain the nature of filament-formation processes in space plasma turbulence with a successful test against the spacecraft observations.
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.
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.
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
L. Zhang, L.-P. Yang, J.-S. He, C.-Y. Tu, L.-H. Wang, E. Marsch, and X.-S. Feng
Ann. Geophys., 33, 13–23, https://doi.org/10.5194/angeo-33-13-2015, https://doi.org/10.5194/angeo-33-13-2015, 2015
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
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
M. Wilczek, H. Xu, and Y. Narita
Nonlin. Processes Geophys., 21, 645–649, https://doi.org/10.5194/npg-21-645-2014, https://doi.org/10.5194/npg-21-645-2014, 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
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