A. Marchaudon's research while affiliated with Research Institute in Astrophysics and Planetology and other places

Publications (58)

Article
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Flux Transfer Events (FTEs) are transient magnetic flux ropes typically found at the Earth's magnetopause on the dayside. While it is known that FTEs are generated by magnetic reconnection, it remains unclear how the details of magnetic reconnection controls their properties. A recent study showed that the helicity sign of FTEs positively correlate...
Article
Full-text available
The geomagnetic field is composed of a variety of sources that act on a wide range of timescales and amplitudes. The separation of magnetic storm effects from quiet variations is needed to accurately quantify impacts of space weather events. The extraction of such quiet contributions within geomagnetic measurements is achieved by the determination...
Preprint
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Based on ray tracing in a smooth ionosphere described by the IRI-2016 model we have infered the seasonal-diurnal dynamics of radio noise observed by four mid-latitude HF radars. In the calculations, noise is assumed to propagate from the radar dead zone boundary. Noise absorption along the ray path is simulated from the IRI-2016 electron density, a...
Article
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Plain Language Summary The Earth's near‐space environment is very dynamic with transient phenomena triggered by interaction between the solar wind and the Earth's magnetopause. The solar wind carries along an interplanetary magnetic field (IMF) whose orientation determines the dynamics of the interaction. When the IMF is southward, magnetic reconne...
Article
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An analysis of noise attenuation during eighty solar flares between 2013 and 2017 was carried out at frequencies 8‐20 MHz using thirty‐four SuperDARN radars and the EKB ISTP SB RAS radar. The attenuation was determined on the basis of noise measurements performed by the radars during the intervals between transmitting periods. The location of the p...
Article
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We present a new web service (http://transplanet.irap.omp.eu/) dedicated to the modeling of planetary ionospheres. Thanks to the development made for IRAP ionospheric model IPIM, it uses a unified description of the different ionized environments (presently Venus, Earth, Mars and Jupiter). The service provides a complete set of parameters character...
Preprint
An analysis of noise attenuation during eighty solar flares between 2013 and 2017 was carried out at frequencies 8-20 MHz using thirty-four SuperDARN radars and the EKB ISTP SB RAS radar. The attenuation was determined on the basis of noise measurements performed by the radars during the intervals between transmitting periods. The location of the p...
Article
Our aim is to understand the effect of high-speed stream events on the high-latitude ionosphere and more specifically the decrease of the foF2 frequency during the entire day following the impact. First, we have selected one summertime event, for which a large data set was available: Super Dual Auroral Radar Network (SuperDARN) and European Incoher...
Article
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The occurrence of spatially and temporally variable reconnection at the Earth's magnetopause leads to the complex interaction of magnetic fields from the magnetosphere and magnetosheath. Flux Transfer Events (FTEs) constitute one such type of interaction. Their main characteristics are 1/ an enhanced core magnetic field magnitude and 2/ a bipolar m...
Article
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Taking advantage of high-resolution measurements from the MMS mission, we find evidence for a complete Hall system in the exhaust of asymmetric magnetic reconnection 40 Di downstream of the X line. The investigation of the fine structure of the Hall system reveals that it displays features in the exhaust similar to those reported previously in the...
Article
The Europlanet 2020 Research Infrastructure will include new Planetary Space Weather Services (PSWS) that will extend the concepts of space weather and space situational awareness to other planets in our Solar System and in particular to spacecraft that voyage through it. PSWS will make five entirely new toolkits accessible to the research communit...
Article
The Magnetospheric Multiscale mission has demonstrated the frequent presence of reconnection exhausts at thin current sheets within Kelvin-Helmholtz (KH) waves at the flank magnetopause. Motivated by these recent observations, we performed a statistical analysis of the boundary layers on the magnetosheath side of all KH current sheets on 8 Septembe...
Article
Theory predicts that the first adiabatic invariant of a charged particle may be violated in a region of highly curved field lines, leading to significant pitch angle scattering for particles whose gyroradius are comparable to the radius of the magnetic field line curvature. This scattering generates more isotropic particle distribution functions, w...
Article
Based on high-resolution measurements from NASA's Magnetospheric Multiscale mission, we present the dynamics of electrons associated with current systems observed near the diffusion region of magnetic reconnection at Earth's magnetopause. Using pitch angle distributions (PAD) and magnetic curvature analysis we demonstrate the occurrence of electron...
Article
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The fine magnetic field structure of two successive plasmoids previously reported is investigated by magnetic rotation analysis using four Cluster satellite data. Between these two plasmoids, opposite trends of curvature radius (Rc) variations of the magnetic field lines from the boundary to the inner part are found. The different variations of Rc...
Article
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[1] New subauroral K-derived sector indices are proposed. They are based on the K local geomagnetic activity indices from the planetary am network stations, and their derivation scheme draws directly from that of am indices. Four Magnetic Local Time (MLT) sectors are considered, leading to four different K-derived MLT sector indices: the aσDawn (03...
Article
The ionosphere is known to play a key role in the electrodynamics of the magnetosphere, but the interhemispheric asymmetries and the connexions between the two hemispheres along the closed magnetic field lines introduce a new feature, the interhemispheric dynamics, which may have a significant contribution to the overall equilibrium. In order to ac...
Article
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How the solar wind affects the location of the magnetopause has been widely studied and excellent models of the magnetopause based on in situ observations in the solar wind and at the magnetopause have been established, while the careful insight into the responses of the magnetopause to the variations in the solar wind can still provide us some new...
Article
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We present a technique to measure the magnetic field-aligned vorticity of mesoscale plasma flows in the F region ionosphere using line-of-sight velocity measurements made by the Super Dual Auroral Radar Network (SuperDARN). Vorticity is often used as a proxy for magnetic field-aligned current (FAC) intensity in the ionosphere but also provides info...
Article
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The Cluster mission offers a unique opportunity to investigate the origin of the energy-dispersed ion structures frequently observed at 4.5–5 RE altitude in the auroral region. We present a detailed study of the 14 February 2001 northern pass, characterized by the successive observation by three spacecraft of a series of energy-dispersed structures...
Article
In order to study the impact of coupling between hemispheres on the dynamics of the ionospheric and magnetospheric plasma, a new interhemispheric ionospheric model has been developed with a dipolar geomagnetic field geometry. This new model is based on a multi-fluid approach for ions and thermal electrons and a kinetic approach for suprathermal ele...
Article
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The role of intense high-altitude electric field (E-field) peaks for large-scale plasma convection is investigated with the help of Cluster E-field, B-field and density data. The study covers 32 E-field events between 4 and 7 R<sub>E</sub> geocentric distance, with E-field magnitudes in the range 500–1000 mV/m when mapped to ionospheric altitude. W...
Article
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Results are presented from a case study of a plasma boundary crossing by the Cluster spacecraft during an extended period of high auroral activity. The boundary between the magnetotail lobe region of the Southern Hemisphere and the plasma sheet boundary layer, was characterized by intense electric and magnetic field variations, structured upward ac...
Article
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We present space- and ground-based observations of the signatures of magnetic reconnection during an interval of duskward-oriented interplanetary magnetic field on 25 March 2004. In situ field and plasma measurements are drawn from the Double Star and Cluster satellites during traversals of the pre-noon sector dayside magnetopause at low and high l...
Article
Particles with energies of tens to hundreds of keV provide a powerful diagnostic of the acceleration processes that characterise the Earth’s magnetosphere, in particular the highly dynamic nightside plasma sheet. Such energetic particles can be detected by the RAPID experiment, onboard the quartet of Cluster spacecraft. We present results from the...
Article
Cluster observations in the near-Earth plasma sheet boundary layer (PSBL) region have shown the presence of ion shell distributions related to velocity-dispersed ion structures (VDIS) coincident with electrostatic emissions. We have examined ion shell instabilities in the presence of a cold ion and electron background using linear theory and partic...
Article
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The profile of intense high-altitude electric fields on auroral field lines has been studied using Cluster data. A total of 41 events with mapped electric field magnitudes in the range between 0.5–1 V/m were examined, 27 of which were co-located with a plasma boundary, defined by gradients in particle flux, plasma density and plasma temperature. Mo...
Article
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1] This paper presents a detailed study of the Feb. 14, 2001 Cluster northern auroral pass at mid-altitudes (4 –5 R E), characterized by observations of a series of energy-dispersed ion structures in a region of poleward convection. In contradiction with one current view, that ions populating these energy-dispersed signatures originate sporadically...
Chapter
This paper reviews Cluster observations of the high altitude and exterior (outer) cusp, and adjacent regions in terms of new multi-spacecraft analysis and the geometry of the surrounding boundary layers. Several crossings are described in terms of the regions sampled, the boundary dynamics and the electric current signatures observed. A companion p...
Article
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On 16 March 2002, Cluster moved from nightside to dayside, across the high-altitude northern cusp during an extended period of relatively steady positive IMF BY and BZ. Combined Cluster and SuperDARN data imply the existence of two reconnection sites: in the high-latitude northern hemisphere dusk and southern hemisphere dawn sectors. Within the cus...
Article
Double Star is an international collaboration between the China National Space Agency (CNSA) and the European Space Agency (ESA), which has produced and launched two magnetospheric research spacecraft, TC-1 and TC-2. TC-1, was launched in late December 2003, and is in a near-equatorial highly elliptical orbit, with apogee at 13.4 Earth radii. TC-2...
Article
Recent Cluster satellite observations made in the Earth's plasma sheet boundary layer (PSBL) region have shown the presence of ion shell distribution functions coincident with broadband electrostatic waves. The shell distribution functions take the form of ions with about the same drift speed isotropically distributed in velocity space on a sphere...
Article
The Cluster spacecraft offer a unique opportunity to investigate the origin of dispersed ion beams observed at mid-latitudes (4-5 RE) in the nightside auroral region. In this paper we present a detailed study of one event observed during the recovery phase of a magnetospheric substorm. In contrast to the suggestion that energetic ions sporadically...
Article
How the signature of auroral electric fields are related to plasma density gradients is investigated in this study using Cluster data. Of the 41 events investigated, 27 are monopolar or bipolar electric field events occurring at density gradients. 11 of these are monopolar events and all except one are found to be associated with the sharp density...
Article
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We present Cluster and Double Star-1 (TC-1) observations from a close magnetic conjunction on 8 May 2004. The five spacecraft were on the dawnside flank of the magnetosphere, with TC-1 located near the equatorial plane and Cluster at higher geographic latitudes in the Southern Hemisphere. TC-1, at its apogee, skimmed the magnetopause for almost 8h...
Article
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A little more than four years after its launch, the first magnetospheric, multi-satellite mission Cluster has already tremendously contributed to our understanding about the coupled solar wind - magnetosphere - ionosphere system. This is mostly due to its ability, for the first time, to provide instantaneous spatial views of structures in the syste...
Article
When the apogee of the Cluster spacecraft is on the day-side between mid-January and mid-April each year, the 4 spacecraft spend several hours per orbit upstream of the bow shock, and thus sample the fields and plasmas of the solar wind. The multi-point nature of the mission allows unambiguous determination of many properties of structures converti...
Article
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This paper uses 90 min of Cluster multipoint data at ∼5 RE altitude together with global dayside imaging data provided by the IMAGE-SI-12 instrument to analyze the northern cusp crossed on 14 July 2001, during a period of high solar wind pressure Psw and strongly duskward interplanetary magnetic field (IMF). Simultaneous observations reveal intense...
Article
Full-text available
On 16 March 2002, Cluster moved from nightside to dayside, across the high-altitude northern cusp during an extended period of relatively steady positive IMF B Y and B Z. Combined Cluster and SuperDARN data imply the existence of two reconnection sites: in the high-latitude northern hemisphere dusk and southern hemisphere dawn sectors. Within the c...
Article
Synoptic measurements from the DOUBLE STAR and CLUSTER spacecraft offer a unique opportunity to evaluate global models in simulating the complex topology and dynamics of the dayside merging region. We compare observations from the DOUBLE STAR TC-1 and CLUSTER spacecraft on May 8, 2004 with the predictions from a three-dimensional magnetohydrodynami...
Article
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[I] We describe coordinated observations made on 14 July 2001 simultaneously in the midaltitude cusp by Cluster and at the cusp's ionospheric magnetic footprint by Super Dual Auroral Radar Network (SuperDARN) and Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) during a period of three successive solar wind dynamic pressure pulses. In a...
Article
Full-text available
On 12 September 1999, a conjunction between two SuperDARN radars and the Ørsted satellite gave, for the first time, simultaneous access to the ionospheric convection enhancement and the field-aligned currents (FACs) associated with a Flux Transfer Event. The radars observed an azimuthally elongated convection flow burst and the Ørsted satellite obs...
Article
The association between the CLUSTER spacecraft and ground-based radars offers a unique opportunity to observe the signatures of transient reconnection simultaneously in the vicinity of the dayside magnetopause and at low altitude in the ionosphere. We report here on such observations on March 17, 2001, during a short period when the IMF turns south...
Article
We study the motion of dayside magnetospheric boundaries on August 30, 2001, dur- ing a period characterised by a steady negative IMF By, and a progressive transition of the Bz component from strongly negative to close to zero. The parallel currents are deduced from a series of three simultaneous passes of the CHAMP and ØRSTED magnetic satellites d...
Article
The SuperDARN (Dual Auroral Radar Network) coherent HF radars monitor the large-scale ionospheric convection from the Doppler shift affecting the signal coherently backscattered by electron density irregularities frozen in the ionospheric plasma. A network of 15 radars with a field of view covering the northern and southern auroral zones and polar...
Article
The SuperDARN HF radars measure the convection velocity of the plasma in the magnetosphere and ionosphere with a high-time resolution (1 min) and a large spatial coverage. They are thus complementary to in-situ measurements by earth satellites allowing their integration into a global view of the dynamical magnetospheric system. We present a few exa...
Article
Magnetosheath plasma enters the magnetosphere along cusp field lines during sporadic reconnection events (flux transfer events or FTEs). It is expected that these enhanced parallel plasma flows occur simultaneously with enhanced ionospheric convection events driven by the magnetic tension at the reconnection site. Associated optical auroral emissio...
Article
The multi-satellite mission Cluster is an opportunity to study structure and dynamics of the polar cusp. On the 17th of March 2001, Cluster enters the high altitude cusp over the northern hemisphere during variable interplanetary magnetic field (IMF) and quiet conditions(P
Article
The present study deals with the characteristics (location, upward flux) and the time evolution of the oxygen ion source that leads to the outflow observed in the dayside high-latitude regions by the Cluster multi-satellite at geocentric distances from 4 up to 8 Earth radii. Upflowing oxygen distributions are recorded by the CIS/CODIF experiment an...

Citations

... The Earth's cusp is often described as a narrow funnel-shaped region populated with particles of shocked solar wind energies, located on open magnetic field lines and usually characterized with significant turbulence and depressed local magnetic field [Frank, 1971;Heikkila and Winningham, 1971;Dunlop et al., 2005]. ...
... Other formation mechanisms were also proposed based on single X-line reconnection due to the nature of unsteady or transient reconnection (e.g., Southwood et al., 1988;Scholer, 1988). More recently, there are increasing evidence supporting FTE generation due to multiple X-line reconnection (e.g., Hasegawa et al., 2010;Kieokaew et al., 2021;Øieroset et al., 2011;Trenchi et al., 2011). After their initial formation, FTEs undergo dynamical evolution due to continuous reconnection while propagating poleward (e.g., Akhavan-Tafti et al., 2019;Hoilijoki et al., 2019;Hwang et al., 2020;Guo et al., 2021). ...
... 3 of 20 As a result of the above considerations, Berngardt et al. (2019) suggested that the observed noise pattern was not so much related to the source of noise in poleward pointing mid-latitude HF radars as it was related to ionospheric conditions. The authors proposed that in most cases the sources of noise should be considered to be anthropogenic and that the noise pattern is dictated by the border of the so-called "skip zone" often observed though ionospheric ground echoes (Samson et al., 1990). ...
... The Jovian atmospheric model considered here has been adapted to Juno studies by Wang et al. (2021) from the Jupiter Transplanet Atmosphere Model (Blelly et al., 2019), which is a semi empirical model using the assumptions of diffusive equilibrium well above the homopause and of mixed equilibrium well below the homopause. Its theoretical foundations are described in Banks and Kockarts (1973). ...
... It showed to me how difficult it is to find the causes of magnetospheric disturbances. With different techniques there is still an uncertainty of more than ten hours as regards predicting the arrival of ICMEs at the Earth Rodriguez et al., 2009;Cid et al., 2012;Cremades et al., 2015;Bocchialini et al., 2018). ...
Reference: Reminiscences
... TDIM, a physics-based mid-latitude model [67] was modified to include high latitude ionospheric effects of particle precipitation, electric field convection, plasma transport processes, electron density, and electron temperatures [68]. The IRAP plasmasphere-ionosphere model (IPIM), a 3-D multifluid mathematical model for interhemispheric studies [69] showed that electron density depletion results from a decrease of neutral atomic oxygen concentration and 2 / ON ratio; these results also closely match with the ionosonde and EISCAT radar data [70]. Theoretical models generally use statistic inputs that define precipitation, convection, and conductance rates to reproduce the complex mechanisms occurring in the auroral regions. ...
... Also, recent observations suggest that the reconnection could occur at such a current sheet at the magnetopause (Øieroset et al., 2016). However, further analyses show that these intense reconnecting current sheets were created by two interlaced flux tubes rather than inside the center of one standard FR, because the electron pitch angle distributions (PAD) on the two sides of the intense current sheet were quite different, which indicates that the plasmas on the two sides were not magnetically connected Kacem et al., 2018;Kieokaew et al., 2020;Øieroset et al., 2019). Latest statistics show that the ubiquitous intense current sheet, where the reconnection was common, observed at the centers of the rope-like structures was caused by two interlinked flux tubes . ...
... With the presence of a moderate guide field, previous simulation results showed that Hall fields displayed a quadrupolar pattern with strong asymmetric intensities under asymptotic asymmetric conditions (Pritchett & Mozer 2009). Recent MMS observations showed that quadrupolar Hall fields can be present under asymptotic asymmetric conditions at the magnetopause and can display nearly symmetric intensities with or without a guide field (Peng et al. 2017;Wang et al. 2017;Zhang et al. 2017). The past results and recent results indicate that the asymptotic condition is not precise enough on its own to evaluate the features of the Hall effect. ...
... Space weather phenomena at other solar system objects and at astropheres are the subject of increasing interest (cf., Lilensten et al., 2014;Plainaki et al., 2016;André et al., 2018). More recently, space weather phenomena in astropheres harboring extrasolar planets also became the focus of investigations (cf., Pillet et al., 2019). ...
... Using the same MMS event, Li et al. (2016a) reported kinetic evidence of vortex driven reconnection, such as low-energy (<100 eV) magnetosheath electrons entering the magnetosphere and magnetospheric electrons escaping into the magnetosheath through reconnected field lines. Vernisse et al. (2016) further investigated magnetic topologies of magnetosheath boundary layers observed outside the KHI-corrugated magnetopause surface (Fig. 40a), and found that particle leakage features are consistent with not only local vortex induced reconnection but also mid-latitude reconnection as simulated by Borgogno et al. (2015). These results demonstrate that the 3-D development of the KHI can induce plasma entry through reconnection at both mid-latitude and equatorial regions already sunward of the dawn-dusk terminator where the KHI is in its early nonlinear phase. ...