Publications

2022

• Magnetic Signatures of Large-Scale Electric Currents in the Earth’s Environment at Middle and Low Latitudes
  
  • Amory-Mazaudier Christine
  Atmosphere, MDPI, 2022, 13 (10), pp.1699. The purpose of space weather is the systemic study of the Sun–Earth system, in order to determine the impact of solar events on the electromagnetic environment of the Earth. This article proposes a new transdisciplinary approach of the Sun–Earth system based on the universal physical process of the dynamo. The dynamo process is based on two important parameters of the different plasmas of the Sun–Earth system, the motion and the magnetic field. There are four permanent dynamos in the Sun–Earth system: the solar dynamo, the Earth dynamo, the solar wind-magnetosphere dynamo, and the ionospheric dynamo. These four permanent dynamos are part of different scientific disciplines. This transdisciplinary approach links all of these dynamos in order to understand the variations in the Earth’s magnetic field. During a magnetic disturbed period, other dynamos exist. We focused on the ionospheric disturbed dynamo generated by Joule energy dissipated in the high latitude ionosphere during magnetic storms. Joule heating disrupts the circulation of thermospheric winds and in turn generates disturbances in the Earth’s magnetic field. This systemic approach makes it possible to understand magnetic disturbances previously not well understood. (10.3390/atmos13101699)
  DOI : 10.3390/atmos13101699
• BepiColombo 2nd Mercury flyby: Ion composition measurements from the Mass Spectrum Analyzer onboard Mio
  
  • Hadid L. Z.
  • Delcourt Dominique
  • Saito Yoshifumi
  • Fraenz Markus
  • Yokota Shoichiro
  • Fiethe Bjorn
  • Verdeil Christophe
  • Katra Bruno
  • Leblanc Frederic
  • Fischer Henning
  • Harada Yuki
  • Aizawa Sae
  • André Nicolas
  • Persson Moa
  • Fontaine D.
  • Krupp Norbert
  • Krüger Harald
  • Murakami Go
  • Matsuda Shoya
  , 2022, 2022. On June 23rd 2022, BepiColombo performed its second gravity assist maneuver (MFB2) at Mercury. Just like the first encounter that took place on October 1st 2021, the spacecraft approached the planet from dusk-nightside toward dawn-dayside, traveling down to an extremely close distance (at ~198 km altitude above the planet's surface). This distance is smaller than that of the two BepiColombo orbiters when they will orbit the planet after insertion in 2025. Even though BepiColombo is in a so-called "stacked configuration" during cruise (meaning that most of the instruments cannot be fully operated yet), the instruments can still make interesting observations. Particularly, despite their limited field-of-view, the particle sensors allow us to get a hint on the plasma composition and dynamics very close to the planet. In this presentation, we will show the first observations of the Mass Spectrum Analyzer (MSA) at Mercury during MFB2. MSA is part of the Mercury Plasma Particle Experiment (MPPE, PI: Y. Saito) consortium that is a comprehensive instrumental suite for plasma, high-energy particle and energetic neutral atom measurements onboard Mio (Saito et al. 2021). MSA is a time-of-flight spectrometer that provides information on the plasma composition and the three-dimensional ion distribution functions in the ~ 10 eV/q-38 keV/q energy range and in the ~ 1-60 amu mass range (Delcourt et al. 2016). We will focus on the ion composition (1) at the closest approach that occurred around 09:44 UT, and (2) during the outbound sequence in the foreshock region between ~10:00 UT and ~ 10:30 UT.
• What is the role of oblique whistler waves in shaping of the solar wind electron function between 0.17 and 1 AU ?
  
  • Colomban Lucas
  • Kretzschmar Matthieu
  • Krasnoselskikh Vladimir
  • Maksimovic Milan
  • Graham Daniel
  • Khotyainsev Yuri
  • Berĉiĉ Laura
  • Berthomier Matthieu
  • Froment Clara
  , 2022. In the solar wind, whistler waves are thought to play an important role on the evolution of the electron velocity distribution function as a function of distance. In particular, oblique whistler waves may diffuse the Strahl electrons into the halo population. Using AC magnetic and electric field measured by the SCM (search coil magnetometer) and electric antenna of Solar Orbiter and Parker Solar Probe, we search for the presence of whistler waves at heliocentric distance between 0.17 and 1 AU. Spectral matrices computation and minimum variance analysis on continuous waveforms make it possible to identify whistler wave modes and to determine their direction of propagation with respect to the ambiant magnetic field (angle and direction : sunward or anti-sunward) . A statistical study of the inclination of these waves and of their parameters is presented and allows us to make assumptions about their roles. Single events are also presented in details (10.5194/egusphere-egu22-7265)
  DOI : 10.5194/egusphere-egu22-7265
• Initial Results of the Second Mercury Flyby Observation by MPPE (Mercury Plasma Particle Experiment) on BepiClombo/Mio
  
  • Saito Yoshifumi
  • Delcourt Dominique
  • André Nicolas
  • Hirahara Masafumi
  • Barabash Stanislav V.
  • Takashima Takeshi
  • Asamura Kazushi
  • Aizawa Sae
  • Harada Yuki
  • Hadid L. Z.
  , 2022, 2022. The Mercury Plasma/Particle Experiment (MPPE) is a comprehensive instrument package on BepiColombo/Mio spacecraft for plasma, high-energy particle and energetic neutral atom measurements. It consists of 7 sensors: two Mercury Electron Analyzers (MEA1 and MEA2), Mercury Ion Analyzer (MIA), Mass Spectrum Analyzer (MSA), High Energy Particle instrument for electron (HEP-ele), High Energy Particle instrument for ion (HEP-ion), and Energetic Neutrals Analyzer (ENA). <P />Before arriving at Mercury in December 2025, BepiColombo experiences multiple Venus and Mercury flybys. The second Mercury flyby was on 23 June 2022. The closest approach was at an altitude of about 200 km from Mercury's surface, and BepiColombo approached Mercury's magnetosphere from the dusk-side tail, crossed the low-altitude regions in the dawn-side southern hemisphere, and exited the magnetosphere on the dayside in the southern hemisphere. <P />Although the MOSIF (MMO Sunshield and Interface Structure) blocked most of the MPPE sensor's field of view until arrival at Mercury, all the MPPE sensors except HEP-ion were turned on to observe Mercury's magnetosphere during the Mercury flybys. <P />During the second Mercury flyby, MEA and MIA succeeded in observing energy spectra of low energy electrons and ions in the Mercury magnetosphere. In-bound and out-bound magnetopause were identified by MEA and MIA, where multiple crossings of the magnetopause were observed at the in-bound magnetopause, and single sharp magnetopause crossing was observed at the out-bound magnetopause. Inverted-V like signatures were observed by MEA in the magnetosphere. MSA also succeeded in observing mass identified ion energy spectra. H+, He+, and He++ were clearly identified while the energy spectra of total ions were consistent with MIA. HEP-ele detected decrease of the high-energy electrons below 190keV around the closest approach that was caused by the blockage of the high energy electrons by the planet Mercury. ENA detected two types of neutral particle signatures: one is neutrals generated by ion impact on the MOSIF and the other is natural neutrals from Mercury magnetosphere. MPPE data obtained during the second Mercury flyby show very active nature of the Mercury magnetosphere.
• Enhancement of the Nonresonant Streaming Instability by Particle Collisions
  
  • Marret Alexis
  • Ciardi Andrea
  • Smets Roch
  • Fuchs Julien
  • Nicolas Loic
  Physical Review Letters, American Physical Society, 2022, 128 (11), pp.115101. Streaming cosmic rays can power the exponential growth of a seed magnetic field by exciting a nonresonant instability that feeds on their bulk kinetic energy. By generating the necessary turbulent magnetic field, it is thought to play a key role in the confinement and acceleration of cosmic rays at shocks. In this Letter we present hybrid-particle-in-cell simulations of the nonresonant mode including Monte Carlo collisions, and investigate the interplay between the pressure anisotropies produced by the instability and particle collisions in the background plasma. Simulations of poorly ionized plasmas confirm the rapid damping of the instability by proton-neutral collisions predicted by linear fluid theory calculations. In contrast we find that Coulomb collisions in fully ionized plasmas do not oppose the growth of the magnetic field, but under certain conditions suppress the pressure anisotropies and actually enhance the magnetic field amplification. (10.1103/PhysRevLett.128.115101)
  DOI : 10.1103/PhysRevLett.128.115101
• The “Singular” Behavior of the Solar Wind Scaling Features during Parker Solar Probe–BepiColombo Radial Alignment
  
  • Alberti Tommaso
  • Milillo Anna
  • Heyner Daniel
  • Hadid L. Z.
  • Auster Hans-Ulrich
  • Richter Ingo
  • Narita Yasuhito
  The Astrophysical Journal, American Astronomical Society, 2022, 926 (2), pp.174. At the end of 2020 September, the Parker Solar Probe (PSP) and BepiColombo were radially aligned: PSP was orbiting near 0.17 au and BepiColombo near 0.6 au. This geometry is of particular interest for investigating the evolution of solar wind properties at different heliocentric distances by observing the same solar wind plasma parcels. In this work, we use the magnetic field observations from both spacecraft to characterize both the topology of the magnetic field at different heliocentric distances (scalings, high-order statistics, and multifractal features) and its evolution when moving from near-Sun to far-Sun locations. We observe a breakdown of the statistical self-similar nature of the solar wind plasma with an increase in the efficiency of the nonlinear energy cascade mechanism when moving away from the Sun. We find a complex organization of large field gradients to dissipate the excess of kinetic energy across the inertial range near the Sun, whereas the topological organization of small fluctuations is still primarily responsible for the energy transfer rate at 0.6 au. These results provide, for the first time, evidence of the different roles of dissipation mechanisms near and far away from the Sun. (10.3847/1538-4357/ac478d)
  DOI : 10.3847/1538-4357/ac478d
• The Persistent Mystery of Collisionless Shocks
  
  • Goodrich Katherine
  • Schwartz Steven
  • Wilson III Lynn
  • Cohen Ian
  • Caspi Amir
  • Smith Keith
  • Rose Randall
  • Whittlesey Phyllis
  • Plaschke Ferdinand
  • Halekas Jasper
  • Hospodarsky George
  • Burch James
  • Gingell Imogen
  • Chen Li-Jen
  • Retino Alessandro
  • Khotyaintev Yuri
  Bulletin of the American Astronomical Society, American Astronomical Society, 2022, 55 (3). Collisionless shock waves are one of the main forms of energy conversion in space plasmas. They can directly or indirectly drive other universal plasma processes such as magnetic reconnection, turbulence, particle acceleration and wave phenomena. Collisionless shocks employ a myriad of kinetic plasma mechanisms to convert the kinetic energy of supersonic flows in space to other forms of energy (e.g., thermal plasma, energetic particles, or Poynting flux) in order for the flow to pass an immovable obstacle. The partitioning of energy downstream of collisionless shocks is not well understood, nor are the processes which perform energy conversion. While we, as the heliophysics community, have collected an abundance of observations of the terrestrial bow shock, instrument and mission-level limitations have made it impossible to quantify this partition, to establish the physics within the shock layer responsible for it, and to understand its dependence on upstream conditions. This paper stresses the need for the first ever spacecraft mission specifically designed and dedicated to the observation of both the terrestrial bow shock as well as Interplanetary shocks in the solar wind. (10.3847/25c2cfeb.9053575b)
  DOI : 10.3847/25c2cfeb.9053575b
• Scale-Dependent Kurtosis of Magnetic Field Fluctuations in the Solar Wind: A Multi-Scale Study With Cluster 2003-2015
  
  • Roberts O. W.
  • Alexandrova O.
  • Sorriso-Valvo L.
  • Vörös Z.
  • Nakamura R.
  • Fischer D.
  • Varsani A.
  • Escoubet C. Philippe
  • Volwerk M.
  • Canu Patrick
  • Lion S.
  • Yearby K.
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2022, 127. During the lifetime of the Cluster mission, the inter-spacecraft distances in the solar wind have changed from the large, fluid, scales (∼10<SUP>4</SUP> km), down to the scales of protons (∼10<SUP>2</SUP> km). As part of the guest investigator campaign, the mission achieved a formation where a pair of spacecraft were separated by ∼7 km. The small distances and the exceptional sensitivity of the search coil magnetometer provide an excellent data set for studying solar wind turbulence at electron scales. In this study, we investigate the intermittency of the magnetic field fluctuations in the slow solar wind. Using 20 time intervals with different constellation orientations of Cluster we cover spatial scales between 7 and 10<SUP>4</SUP> km. We compare time-lagged increments from a single spacecraft with spatially lagged increments using multiple spacecraft. As the turbulent cascade proceeds to smaller scales in the inertial range, the deviation from Gaussian statistics is observed to increase in both temporal and spatial increments in the components transverse to the mean field direction. At ion scales, there is a maximum of kurtosis, and at sub-ion scales, the fluctuations are only weakly non-Gaussian. In the compressive component the deviation from Gaussian statistics is variable: it may increase throughout the inertial and sub-ion ranges, but also, it may have a maximum at magnetohydrodynamic scales associated with large scale magnetic holes. The observations show differences in kurtosis of time and space increments when the spacecraft pairs are transverse to the flow, indicating its spatial anisotropy. (10.1029/2021JA029483)
  DOI : 10.1029/2021JA029483
• Massive Multi-Mission Statistical Study and Analytical Modeling of the Earth's Magnetopause: 2. Shape and Location
  
  • Nguyen G.
  • Aunai N.
  • Michotte de Welle B.
  • Jeandet A.
  • Lavraud B.
  • Fontaine D.
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2022, 127. The Earth magnetopause is the boundary between the magnetosphere and the shocked solar wind. Its location and shape are primarily determined by the properties of the solar wind and interplanetary magnetic field (IMF) but the nature of the control parameters and to what extent they impact the stand-off distance, the flaring, and the symmetries, on the dayside and night side, is still not well known. We present a large statistical study of the magnetopause location and shape based an extensive multi-mission magnetopause database, cumulating 17,230 crossings on 17 different spacecraft, from the dayside to lunar nightside distances. The results confirm the power-law dependency of the stand-off position on the solar wind pressure. The IMF clock angle itself (all amplitudes combined) does not impact the stand-off distance, nor does the cone angle. However, the magnetopause is found to move Earthward as the IMF gets stronger and more southward. All upstream conditions combined, it is found that the function used at the root of several analytical models still holds at lunar distances. We find that the equatorial flaring is larger than the meridional one. However, the meridional flaring is found to depend on the seasonal tilt conditions, being larger in the summer hemisphere. The flaring is also found to depend on the IMF clock angle. Meridional flaring increases as the IMF turns south and is then larger than the equatorial flaring. The equatorial flaring barely changes or weakly increases as the IMF turns northward, and is larger than the meridional flaring for northward conditions. The results of the study pave the way for the elaboration of a new analytical empirical expression of the magnetopause location and shape. (10.1029/2021JA029774)
  DOI : 10.1029/2021JA029774
• The RayGalGroupSims cosmological simulation suite for the study of relativistic effects: an application to lensing-matter clustering statistics
  
  • Rasera Y.
  • Breton M-A.
  • Corasaniti P-S.
  • Allingham J.
  • Roy F.
  • Reverdy V.
  • Pellegrin T.
  • Saga S.
  • Taruya A.
  • Agarwal S.
  • Anselmi S.
  Astronomy & Astrophysics - A&A, EDP Sciences, 2022, 661, pp.A90. General Relativistic effects on the clustering of matter in the universe provide a sensitive probe of cosmology and gravity theories that can be tested with the upcoming generation of galaxy surveys. Here, we present a suite of large volume high-resolution N-body simulations specifically designed to generate light-cone data for the study of relativistic effects on lensing-matter observables. RayGalGroupSims (or in short RayGal) consists of two N-body simulations of $(2625\,h^{-1}\,{\rm Mpc})^3$ volume with $4096^3$ particles of a standard flat $\Lambda$CDM model and a non-standard $w$CDM phantom dark energy model. Light-cone data from the simulations have been generated using a parallel ray-tracing algorithm that has accurately solved billion geodesic equations. Catalogues and maps with relativistic weak-lensing which include post-Born effects, magnification bias (MB) and redshift space distortions (RSD) due to gravitational redshift, Doppler, transverse Doppler, Integrated Sachs-Wolfe/Rees-Sciama effects, are publicly released. Using this dataset, we are able to reproduce the linear and quasi-linear predictions from the Class relativistic code for the 10 (cross-)power spectra (3$\times$2 points) of the matter density fluctuation field and the gravitational convergence at $z=0.7$ and $z=1.8$. We find 1-30% level contribution from both MB and RSD to the matter power spectrum, while the Fingers-of-God effect is visible at lower redshift in the non-linear regime. MB contributes at the $10-30\%$ level to the convergence power spectrum leading to a deviation between the shear power-spectrum and the convergence power-spectrum. MB also plays a significant role in the galaxy-galaxy lensing by decreasing the density-convergence spectra by $20\%$, while coupling non-trivial configurations (such as the one with the convergence at the same or even lower redshift than the density field). (10.1051/0004-6361/202141908)
  DOI : 10.1051/0004-6361/202141908
• Massive Multi‐Mission Statistical Study and Analytical Modeling of the Earth's Magnetopause: 4. On the Near‐Cusp Magnetopause Indentation
  
  • Nguyen G.
  • Aunai N.
  • Michotte de Welle Bayane
  • Jeandet A.
  • Lavraud B.
  • Fontaine D.
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2022, 127 (1), pp.e2021JA029776. The shape and location of the magnetopause current sheet in the near-cusp region is still a debated question. Over time, several observations led to contradictory conclusions regarding the presence of an indentation of the magnetopause in that region. As a result several empirical models consider the surface is indented in that region, while some others do not. To tackle this issue, we fit a total of 17,230 magnetopause crossings to various indented and non-indented analytical models. The results show that while all models describe the magnetopause position and shape equivalently far from the cusp region, the non-indented version over-estimate the radial position of the near-cusp magnetopause. Among indented models, we show that the one designed from non-linearmagneto hydrodynamic simulations fits well the near-cusp magnetopause location, while the other underestimate its position probably because their design was possibly based on magnetopause crossing catalogs that contain cusp inner boundary crossings. (10.1029/2021JA029776)
  DOI : 10.1029/2021JA029776
• Massive Multi‐Mission Statistical Study and Analytical Modeling of the Earth's Magnetopause: 1. A Gradient Boosting Based Automatic Detection of Near‐Earth Regions
  
  • Nguyen G.
  • Aunai N.
  • Michotte de Welle B.
  • Jeandet Alexis
  • Lavraud B.
  • Fontaine D.
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2022, 127 (1), pp.e2021JA029773. We present an automatic classification method of the three near-Earth regions, the magnetosphere, the magnetosheath and the solar wind from their in situ data measurement by multiple spacecraft. Based on gradient boosting classifier, this very simple and very fast method outperforms the detection routines based on manually set thresholds. The method is used to identify 15,062 magnetopause crossings and 17,227 bow shock crossings in the data of 11 different spacecraft of the THEMIS, ARTEMIS, Cluster, MMS, and Double Star missions and for a total of 83 cumulated years. These multi-mission catalogs are easily reproducible, can be automatically enlarged with additional data and their elaboration paves the way for future massive statistical analysis of near-Earth boundaries. (10.1029/2021JA029773)
  DOI : 10.1029/2021JA029773
• Enceladus and Titan: emerging worlds of the Solar System
  
  • Sulaiman Ali H.
  • Achilleos Nicholas
  • Bertucci Cesar
  • Coates Andrew
  • Dougherty Michele
  • Hadid Lina
  • Holmberg Mika
  • Hsu Hsiang-Wen
  • Kimura Tomoki
  • Kurth William
  • Le Gall Alice
  • Mckevitt James
  • Morooka Michiko
  • Murakami Go
  • Regoli Leonardo
  • Roussos Elias
  • Saur Joachim
  • Shebanits Oleg
  • Solomonidou Anezina
  • Wahlund Jan-Erik
  • Waite J. Hunter
  Experimental Astronomy, Springer Link, 2022, 54, pp.849-876. Some of the major discoveries of the recent Cassini-Huygens mission have put Titan and Enceladus rmly on the Solar System map. The mission has revolutionised our view of Solar System satellites, arguably matching their scienti c importance with that of their host planet. While Cassini-Huygens has made big surprises in revealing Titan’s organically rich environment and Enceladus’ cryovolcanism, the mission’s success naturally leads us to further probe these ndings. We advocate the acknowl- edgement of Titan and Enceladus science as highly relevant to ESA’s long-term roadmap, as logical follow-on to Cassini-Huygens. In this White Paper, we will out- line important science questions regarding these satellites and identify the science themes we recommend ESA cover during the Voyage 2050 planning cycle. Address- ing these science themes would make major advancements to the present knowledge we have about the Solar System, its formation, evolution, and likelihood that other habitable environments exist outside the Earth’s biosphere. (10.1007/s10686-021-09810-z)
  DOI : 10.1007/s10686-021-09810-z
• Structure and Variability of Low-Energy Ions in Mercury's Magnetosphere: Initial Results from BepiColombo Mio MIA Observations
  
  • Harada Yuki
  • Saito Yoshifumi
  • Aizawa Sae
  • Hadid L. Z.
  • André Nicolas
  • Persson Moa
  • Delcourt Dominique
  • Fraenz Markus
  • Yokota Shoichiro
  • Murakami Go
  • Fedorov Andrei
  • Miyake Wataru
  • Penou Emmanuel
  • Barthe Alain
  • Savaud Jean-André
  • Katra Bruno
  • Matsuda Shoya
  , 2022, 2022. We present initial results from low-energy ion measurements by the Mercury Ion Analyzer (MIA) on board BepiColombo Mio during the first and second Mercury flybys. The orbital configurations of the two flybys were very similar, but the ion properties observed by MIA are significantly different presumably because of different upstream solar wind conditions. Specifically, the ion energies are generally lower during the first flyby than the second flyby, suggesting slower solar wind conditions in the former case. The ion energy spectra obtained during the first flyby suggest the presence of a relatively cold dense ion component in the midnight magnetotail, sources and transport mechanisms of which remain elusive. Additionally, by utilizing an MIA data product that is originally designed to separate ion directions according to the spacecraft spin phase, we derive bonus data of high-time resolution (>~1 s) ion flux measurements from non-spinning observations during the cruise phase. Such high-time resolution measurements could be useful to investigate boundary dynamics, ion kinetics, etc. These flyby observations with limited capabilities suggest rich dynamics of low-energy ions in Mercury's magnetosphere, more complete views of which will be derived from future in-orbit observations of full 3-dimensional ion velocity distribution functions by MIA, along with ion composition and magnetic field measurements by other instruments on Mio.
• Massive Multi-Mission Statistical Study and Analytical Modeling of the Earth's Magnetopause: 3. An Asymmetric Non Indented Magnetopause Analytical Model
  
  • Nguyen G.
  • Aunai Nicolas
  • Michotte de Welle Bayane
  • Jeandet A.
  • Lavraud B.
  • Fontaine D.
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2022, 127. In a companion statistical study, we showed that the expression of the magnetopause surface as a power law of an elliptic function of the zenith angle θ holds at lunar distances, that the flaring of the magnetopause surface is influenced by the Interplanetary Magnetic Field (IMF) B<SUB>y</SUB> component and that the IMF B<SUB>x</SUB> component had no influence on the stand-off distance. As a follow-up to these statistical results, this paper presents a new empirical analytical asymmetric and non-indented model of the magnetopause location and shape. This model is obtained from fitting of 15,349 magnetopause crossings using 17 different spacecraft and is parametrized by the upstream solar wind dynamic and magnetic pressures, the IMF clock angle and the Earth dipole tilt angle. The constructed model provides a more accurate prediction of the magnetopause surface location than current Magnetopause surface models, especially on the night side of the magnetosphere. (10.1029/2021JA030112)
  DOI : 10.1029/2021JA030112