Articles | Volume 9, issue 2
https://doi.org/10.5194/gi-9-471-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/gi-9-471-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
16 Dec 2020
Research article |
| 16 Dec 2020
| 16 Dec 2020
Mathematical foundation of Capon's method for planetary magnetic field analysis
Simon Toepfer
CORRESPONDING AUTHOR
Institut für Theoretische Physik,
Technische Universität Braunschweig, Braunschweig, Germany
Yasuhito Narita
Space Research Institute, Austrian Academy of Sciences, Graz, Austria
Institut für Geophysik und extraterrestrische Physik,
Technische Universität Braunschweig,
Braunschweig, Germany
Daniel Heyner
Institut für Geophysik und extraterrestrische Physik,
Technische Universität Braunschweig,
Braunschweig, Germany
Patrick Kolhey
Institut für Geophysik und extraterrestrische Physik,
Technische Universität Braunschweig,
Braunschweig, Germany
Uwe Motschmann
Institut für Theoretische Physik,
Technische Universität Braunschweig, Braunschweig, Germany
DLR Institute of Planetary Research, Berlin,
Germany
Related authors
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.
Leonard Schulz, Karl-Heinz Glassmeier, Ferdinand Plaschke, Simon Toepfer, and Uwe Motschmann
Ann. Geophys., 41, 449–463, https://doi.org/10.5194/angeo-41-449-2023, https://doi.org/10.5194/angeo-41-449-2023, 2023
Short summary
Short summary
The upper detection limit in reciprocal space, the spatial Nyquist limit, is derived for arbitrary spatial dimensions for the wave telescope analysis technique. This is important as future space plasma missions will incorporate larger numbers of spacecraft (>4). Our findings are a key element in planning the spatial distribution of future multi-point spacecraft missions. The wave telescope is a multi-dimensional power spectrum estimator; hence, this can be applied to other fields of research.
Simon Toepfer, Karl-Heinz Glassmeier, and Uwe Motschmann
Ann. Geophys., 41, 253–267, https://doi.org/10.5194/angeo-41-253-2023, https://doi.org/10.5194/angeo-41-253-2023, 2023
Short summary
Short summary
The present study discusses the modeling and interpretation of magnetospheric structures via electromagnetic knots for the first time. The mathematical foundations of electromagnetic knots are presented, and the formalism is reformulated in terms of the classical wave telescope technique. The method is tested against synthetically generated magnetic field data describing a plasmoid as a two-dimensional magnetic ring structure.
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.
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, 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.
Leonard Schulz, Karl-Heinz Glassmeier, Ferdinand Plaschke, Simon Toepfer, and Uwe Motschmann
Ann. Geophys., 41, 449–463, https://doi.org/10.5194/angeo-41-449-2023, https://doi.org/10.5194/angeo-41-449-2023, 2023
Short summary
Short summary
The upper detection limit in reciprocal space, the spatial Nyquist limit, is derived for arbitrary spatial dimensions for the wave telescope analysis technique. This is important as future space plasma missions will incorporate larger numbers of spacecraft (>4). Our findings are a key element in planning the spatial distribution of future multi-point spacecraft missions. The wave telescope is a multi-dimensional power spectrum estimator; hence, this can be applied to other fields of research.
Simon Toepfer, Karl-Heinz Glassmeier, and Uwe Motschmann
Ann. Geophys., 41, 253–267, https://doi.org/10.5194/angeo-41-253-2023, https://doi.org/10.5194/angeo-41-253-2023, 2023
Short summary
Short summary
The present study discusses the modeling and interpretation of magnetospheric structures via electromagnetic knots for the first time. The mathematical foundations of electromagnetic knots are presented, and the formalism is reformulated in terms of the classical wave telescope technique. The method is tested against synthetically generated magnetic field data describing a plasmoid as a two-dimensional magnetic ring structure.
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.
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.
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
Short summary
Short summary
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
Short summary
Short summary
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.
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
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
Short summary
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
Short summary
Short summary
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
Short summary
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
Short summary
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
Short summary
Short summary
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, 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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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, 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
Short summary
Short summary
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
Short summary
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
Related subject area
Signal processing
An optimized and hybrid gating scheme for the suppression of very low-frequency radios in transient electromagnetic systems
On the determination of ionospheric electron density profiles using multi-frequency riometry
Suppression of very low frequency radio noise in transient electromagnetic data with semi-tapered gates
The baseline wander correction based on the improved ensemble empirical mode decomposition (EEMD) algorithm for grounded electrical source airborne transient electromagnetic signals
On the validation of K-index values at Italian geomagnetic observatories
A remote-control datalogger for large-scale resistivity surveys and robust processing of its signals using a software lock-in approach
Dynamic data transmission technology for expendable current profiler based on low-voltage differential signaling
Continuous wavelet transform and Euler deconvolution method and their application to magnetic field data of Jharia coalfield, India
Improvement of density models of geological structures by fusion of gravity data and cosmic muon radiographies
Validation of the k-filtering technique for a signal composed of random-phase plane waves and non-random coherent structures
Smith Kashiram Khare, Paul McLachlan, Pradip Kumar Maurya, and Jakob Juul Larsen
Geosci. Instrum. Method. Data Syst., 13, 27–41, https://doi.org/10.5194/gi-13-27-2024, https://doi.org/10.5194/gi-13-27-2024, 2024
Short summary
Short summary
Data recorded with transient electromagnetics are typically gated to improve the signal-to-noise ratio. Gating corresponds to low-pass filtering of data with the shape of the gate giving the frequency response. We show that standard gate shapes can lead to significant correlation between gates caused by distortion from VLF radios. A multi-objective cost function is used to select optimum gate shapes with less influence from radio noise. Performance is demonstrated using synthetic and field data.
Derek McKay, Juha Vierinen, Antti Kero, and Noora Partamies
Geosci. Instrum. Method. Data Syst., 11, 25–35, https://doi.org/10.5194/gi-11-25-2022, https://doi.org/10.5194/gi-11-25-2022, 2022
Short summary
Short summary
When radio waves from our galaxy enter the Earth's atmosphere, they are absorbed by electrons in the upper atmosphere. It was thought that by measuring the amount of absorption, it would allow the height of these electrons in the atmosphere to be determined. If so, this would have significance for future instrument design. However, this paper demonstrates that it is not possible to do this, but it does explain how multiple-frequency measurements can nevertheless be useful.
Jakob Juul Larsen, Stine Søgaard Pedersen, Nikolaj Foged, and Esben Auken
Geosci. Instrum. Method. Data Syst., 10, 81–90, https://doi.org/10.5194/gi-10-81-2021, https://doi.org/10.5194/gi-10-81-2021, 2021
Short summary
Short summary
The transient electromagnetic method (TEM) is widely used for mapping subsurface resistivity structures, but data are inevitably contaminated by noise from various sources including radio signals in the very low frequency (VLF) 3–30 kHz band. We present an approach where VLF noise is effectively suppressed with a new post-processing scheme where boxcar gates are combined into semi-tapered gates. The result is a 20 % increase in the depth of investigation for the presented test survey.
Yuan Li, Song Gao, Saimin Zhang, Hu He, Pengfei Xian, and Chunmei Yuan
Geosci. Instrum. Method. Data Syst., 9, 443–450, https://doi.org/10.5194/gi-9-443-2020, https://doi.org/10.5194/gi-9-443-2020, 2020
Short summary
Short summary
The baseline wander has special characteristics, such as being low frequency, large amplitude, non-periodic, and non-stationary. It is caused by the receiving coil motion and always exists in the process of data acquisition. The proposed method can be used to solve similar problems. This paper has the following highlights: (1) the method can be used to process non-periodic and non-stationary signals; (2) the method is adaptive to satisfy the stopping criterion based on the measured signal.
Mauro Regi, Paolo Bagiacchi, Domenico Di Mauro, Stefania Lepidi, and Lili Cafarella
Geosci. Instrum. Method. Data Syst., 9, 105–115, https://doi.org/10.5194/gi-9-105-2020, https://doi.org/10.5194/gi-9-105-2020, 2020
Short summary
Short summary
The K index, characterizing local geomagnetic activity, is generally automatically calculated by algorithms such as KASM, one of the four software programs recommended by INTERMAGNET. KASM requires an appropriate L9 value. We analyze K values for Italian observatories and compare them with historical German observatories to establish the best L9 estimation for our stations. A comparison with results from a previous empirical method shows the consistency and reliability of our outcome.
Frank Oppermann and Thomas Günther
Geosci. Instrum. Method. Data Syst., 7, 55–66, https://doi.org/10.5194/gi-7-55-2018, https://doi.org/10.5194/gi-7-55-2018, 2018
Short summary
Short summary
We present a new versatile datalogger that can be used remotely for a wide range of applications in geosciences such as environmental and groundwater monitoring or in applied geophysics. The recorded signals will be processed using a new software approach, which will improve the data quality for very poor signal-to-noise ratios. We show this improvement by comparing it with traditional software-algorithm-processing synthetic data sets and real data collected in the field.
Shuhan Li, Qisheng Zhang, Xiao Zhao, Shenghui Liu, Zhenzhong Yuan, and Xinyue Zhang
Geosci. Instrum. Method. Data Syst., 6, 263–267, https://doi.org/10.5194/gi-6-263-2017, https://doi.org/10.5194/gi-6-263-2017, 2017
Short summary
Short summary
The main contribution of our paper is the proposal of a dynamic data transmission technology of an expendable current profiler, using varnished wires as the data transmission medium. The results of both indoor and marine tests demonstrate high efficiency and accuracy for transmission distances up to 2 km. We believe that this study will be of interest to the readership because our research is of particular interest and use for scientific marine investigation.
Arvind Singh and Upendra Kumar Singh
Geosci. Instrum. Method. Data Syst., 6, 53–69, https://doi.org/10.5194/gi-6-53-2017, https://doi.org/10.5194/gi-6-53-2017, 2017
Short summary
Short summary
Presented work allows estimation of buried source without any prior knowledge of underlying formation. This paper deals the application of continuous wavelet transform (CWT) and Euler deconvolution methods to estimate the source depth using magnetic anomalies. These methods are utilized mainly to focus on the fundamental issue for mapping the major coal seam and locating magnetic lineaments over Jharia coalfield, India.
K. Jourde, D. Gibert, and J. Marteau
Geosci. Instrum. Method. Data Syst., 4, 177–188, https://doi.org/10.5194/gi-4-177-2015, https://doi.org/10.5194/gi-4-177-2015, 2015
Short summary
Short summary
This paper examines how the resolution of small-scale geological density models is improved through the fusion of information provided by gravity measurements and density muon radiographies. The method is illustrated with examples for the La Soufrière volcano of Guadeloupe.
O. W. Roberts, X. Li, and L. Jeska
Geosci. Instrum. Method. Data Syst., 3, 247–254, https://doi.org/10.5194/gi-3-247-2014, https://doi.org/10.5194/gi-3-247-2014, 2014
Cited articles
Anderson, B. J., Johnson, C. L., Korth, H., Purucker, M. E., Winslow, R. M., Slavin, J. A., Solomon, S. C., McNutt Jr., R. L.,
Raines, J. M., and Zurbuchen, T. H.: The global magnetic field of Mercury from MESSENGER orbital observations, Science, 333, 1859–1862, https://doi.org/10.1126/science.1211001, 2011. a
Anderson, B. J., Johnson, C., L., Korth, H., Winslow, R. M., Borovsky, J. E., Purucker, M. E., Slavin, J. A., Solomon, S. C.,
Zuber, M. T., and McNutt Jr., R. L.: Low-degree structure in Mercury's
planetary magnetic field, J. Geophys. Res., 117, E00L12, https://doi.org/10.1029/2012JE004159, 2012. a
Benkhoff, J., van Casteren, J., Hayakawa, H., Fujimoto, M., Laakso, H., Novara, M., Ferri, P., Middleton, H. R., and Ziethe, R.: BepiColombo – Comprehensive exploration of Mercury: Mission overview and science goals, Planet. Space Sci., 85, 2–20, https://doi.org/10.1016/j.pss.2009.09.020, 2010. a
Capon, J.: High resolution frequency-wavenumber spectrum analysis,
Proc. IEEE, 57, 1408–1418, https://doi.org/10.1109/PROC.1969.7278, 1969. a, b
Carlson, B. D.: Covariance matrix estimation errors and diagonal loading in adaptive arrays, IEEE Trans. Aerosp. Electron. Syst., 24, 397–401, https://doi.org/10.1109/7.7181, 1988. a
Constantinescu, O. D., Glassmeier, K.-H., Motschmann, U., Treumann, R. A., Fornaçon, K. -H., and Fränz, M.: Plasma wave source location using CLUSTER as a spherical wave telescope, J. Geophys. Res., 111, A09221, https://doi.org/10.1029/2005JA011550, 2006. a
Gauß, C. F.:
Allgemeine Theorie des Erdmagnetismus: Resultate aus den Beobachtungen des magnetischen Vereins im Jahre 1838, edited by: Gauss, C. F. and Weber, W., Weidmannsche Buchhandlung, Leipzig, 1–57, 1839. a
Glassmeier, K.-H., Motschmann, U., Dunlop, M., Balogh, A., Acuña, M. H., Carr, C., Musmann, G., Fornaçon, K.-H., Schweda, K., Vogt, J., Georgescu, E., and Buchert, S.: Cluster as a wave telescope – first results from the fluxgate magnetometer, Ann. Geophys., 19, 1439–1447, https://doi.org/10.5194/angeo-19-1439-2001, 2001. a
Glassmeier, K.-H., Auster, H.-U., Heyner, D., Okrafka, K., Carr, C., Berghofer, G., Anderson, B. J., Balogh, A., Baumjohann, W., Cargill, P., Christensen, U., Delva, M., Dougherty, M., Fornaçon, K. -H., Horbury, T. S., Lucek, E. A., Magnes, W., Mandea, M., Matsuoka, A., Matsushima, M. Motschmann, U., Nakamura, R., Narita, Y., O'Brien, H., Richter, I., Schwingenschuh, K., Shibuya, H., Slavin, J. A., Sotin, C., Stoll, B., Tsunakawa, H., Vennerstrom, S., Vogt, J., and Zhang, T.: The fluxgate magnetometer of the BepiColombo Mercury Planetary Orbiter, Planet. Space Sci., 58, 287–299, https://doi.org/10.1016/j.pss.2008.06.018, 2010. a
Hiemstra, J. H., Wippert, M. W., Goldstein, J. S., and Pratt, T.:
Application of the L-curve technique to loading level determination in adaptive beamforming,
Conference Record of the Thirty-Sixth Asilomar Conference on Signals, Systems and Computers, Pacific Grove, CA, USA, 2002, Vol. 2, 1261–1266, https://doi.org/10.1109/ACSSC.2002.1196983, 2002. a, b
Ma, N. and Goh, J. T.: Efficient method to determine diagonal loading value, Proc. IEEE Int. Conf. Acoustics, Speech, Signal Processing (ICASSP), 5, 341–344, https://doi.org/10.1109/ICASSP.2003.1199948, 2003. a
Motschmann, U., Woodward, T. I., Glassmeier, K.-H.,
Southwood, D. J., and Pinçon, J.-L.:
Wavelength and direction filtering by magnetic measurements
at satellite arrays: Generalized minimum variance analysis,
J. Geophys. Res., 101, 4961–4966, https://doi.org/10.1029/95JA03471, 1996. a, b, c, d, e, f, g
Müller, J., Simon, S., Motschmann, U., Schüle, J., Glassmeier, K.-H., and Pringle, G. J.: A.I.K.E.F.: Adaptive hybrid model for space plasma simulations,
Comput. Phys. Commun., 182, 946–966, https://doi.org/10.1016/j.cpc.2010.12.033, 2011. a
Narita, Y.:
A note on Capon's minimum variance projection
for multi-spacecraft data analysis,
Front. Phys., 7, 8, https://doi.org/10.3389/fphy.2019.00008, 2019. a, b
Narita, Y., Glassmeier, K.-H., Schäfer, S., Motschmann, U., Sauer, K., Dandouras, I., Fornaçon, K. H., Georgescu, E., and Rème, H.: Dispersion analysis of ULF waves in the foreshock using cluster data and the wave telescope technique, Geophys. Res. Lett., 30, 13, https://doi.org/10.1029/2003GL017432, 2003. a
Narita, Y., Nakamura, R., and Baumjohann, W.: Cluster as current sheet surveyor in the magnetotail, Ann. Geophys., 31, 1605–1610, https://doi.org/10.5194/angeo-31-1605-2013, 2013. a
Pajovic, M., Preisig, J. C., and Baggeroer, A. B.: Analysis of optimal diagonal loading for MPDR-based spatial power estimators in the snapshot deficient regime, IEEE J. Ocean. Eng., 44, 451–465, https://doi.org/10.1109/JOE.2018.2815480, 2018. a, b, c
Pillai, S. U.: Array Signal Processing, Springer Verlag, New York, 8–103, 1989. a
Plaschke, F., Glassmeier, K.-H., Constantinescu, O. D., Mann, I. R., Milling, D. K., Motschmann, U., and Rae, I. J.: Statistical analysis of ground based magnetic field measurements with the field line resonance detector, Ann. Geophys., 26, 3477–3489, https://doi.org/10.5194/angeo-26-3477-2008, 2008. a
Richmond, C. D., Nadakuditi, R. R., and Edelman, A.: Asymptotic mean squared error performance of diagonally loaded Capon-MVDR processor, Conference Record of the Thirty-Ninth Asilomar Conference on Signals, Systems and Computers 2005, Pacific Grove, CA, 1711–1716, 2005. a
Toepfer, S., Narita, Y., Heyner, D., and Motschmann, U.:
The Capon method for Mercury's magnetic field analysis,
Front. Phys., 8, 249, https://doi.org/10.3389/fphy.2020.00249, 2020. a, b, c, d
Tikhonov, A. N., Goncharsky, A., Stepanov, V. V., and Yagola, A. G.: Numerical Methods for the Solution of Ill-Posed Problems, Springer Netherlands, the Netherlands, ISBN 079233583X, 1995. a
Wardinski, I., Langlais, B., and Thébault, E.: Correlated time-varying magnetic field and the core size of Mercury,
J. Geophys. Res., 124, 2178–2197, https://doi.org/10.1029/2018JE005835, 2019. a
Short summary
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.
The Capon method serves as a powerful and robust data analysis tool when working on various...
