References of "Gérard, Jean-Claude"
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See detailJuno Ultraviolet Spectrograph (Juno-UVS) Observations of Jupiter’s Aurora
Greathouse, T.; Veersteeg, M.; Hue, V. et al

Conference (2017, August 11)

The Juno Ultraviolet Spectrograph (UVS) is an imaging Rowland Circle spectrograph mounted on the Juno Spacecraft in orbit about Jupiter. Operating between 70 and 205 nm UVS was built to measure Jupiter’s ... [more ▼]

The Juno Ultraviolet Spectrograph (UVS) is an imaging Rowland Circle spectrograph mounted on the Juno Spacecraft in orbit about Jupiter. Operating between 70 and 205 nm UVS was built to measure Jupiter’s auroral and airglow emissions in the far- to extreme-ultraviolet spectral range (FUV-EUV range). These emissions provide a key link between the on board measurements of Jupiter’s magnetic field and particle populations within the intense Jovian magnetosphere and their interaction with Jupiter’s upper atmosphere.  The UV auroral emissions serve as a “witness plate” or “viewing screen” to some of the complex and powerful magnetospheric processes occurring there. We will present UV images, movies, and color ratio maps of both the northern and southern aurora and discuss how the many features evolve over time from the first Perijove on August 27, 2016 through the 7th Perijove planned on July 11, 2017. [less ▲]

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See detailThe tails of the satellite auroral footprints at Jupiter
Bonfond, Bertrand ULiege; Saur, J.; Grodent, Denis ULiege et al

in Journal of Geophysical Research. Space Physics (2017), 122

The electro-magnetic interaction between Io, Europa and Ganymede and the rotating plasma that surrounds Jupiter has a signature in the aurora of the planet. This signature, called the satellite footprint ... [more ▼]

The electro-magnetic interaction between Io, Europa and Ganymede and the rotating plasma that surrounds Jupiter has a signature in the aurora of the planet. This signature, called the satellite footprint, takes the form of a series of spots located slightly downstream of the feet of the field lines passing through the moon under consideration. In the case of Io, these spots are also followed by an extended tail in the downstream direction relative to the plasma flow encountering the moon. A few examples of a tail for the Europa footprint have also been reported in the northern hemisphere. Here we present a simplified Alfvénic model for footprint tails and simulations of vertical brightness profiles for various electron distribution, which favour such a model over quasi-static models. We also report here additional cases of Europa footprint tails, in both hemispheres, even though such detections are rare and difficult. Furthermore, we show that the Ganymede footprint can also be followed by a similar tail. Finally, we present a case of a 320° long Io footprint tail, while other cases in similar configurations do not display such a length. [less ▲]

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See detailSimilarity of the Jovian satellite footprints: spots multiplicity and dynamics
Bonfond, Bertrand ULiege; Grodent, Denis ULiege; Badman, S. V. et al

in Icarus (2017), 292(2017), 208217

In the magnetospheres of Jupiter and Saturn, the intense interaction of the satellites Io, Europa, Ganymede and Enceladus with their surrounding plasma environment leaves a signature in the aurora of the ... [more ▼]

In the magnetospheres of Jupiter and Saturn, the intense interaction of the satellites Io, Europa, Ganymede and Enceladus with their surrounding plasma environment leaves a signature in the aurora of the planet. Called satellite footprints, these auroral features appear either as a single spot (Europa and Enceladus) or as multiple spots (Io and Ganymede). Moreover, they can be followed by extended trailing tails in the case of Io and Europa, while no tail has been reported for Ganymede and Enceladus, yet. Here we show that all Jovian footprints can be made of several spots. Furthermore, the footprints all experience brightness variations on timescale of 2-3 minutes. We also demonstrate that the satellite location relative to the plasma sheet is not the only driver for the footprint brightness, but that the plasma environment and the magnetic field strength also play a role. These new findings demonstrate that the Europa and Ganymede footprints are very similar to the Io footprint. As a consequence, the processes expected to take place at Io, such as the bi-directional electron acceleration by Alfvén waves or the partial reflection of these waves on plasma density gradients, can most likely be extended to the other footprints, suggesting that they are indeed universal processes. [less ▲]

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See detailNitric oxide airglow limb and nadir from IUVS
Gérard, Jean-Claude ULiege; Stiepen, Arnaud ULiege

Conference (2017, July 05)

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See detailThe thermal structure of the Venus atmosphere: Intercomparison of Venus Express and ground based observations of vertical temperature and density profiles✰
Limaye, Sanjay S.; Lebonnois, Sebastien; Mahieux, Arnaud et al

in Icarus (2017), 294

The Venus International Reference Atmosphere (VIRA) model contains tabulated values of temperature and number densities obtained by the experiments on the Venera entry probes, Pioneer Venus Orbiter and ... [more ▼]

The Venus International Reference Atmosphere (VIRA) model contains tabulated values of temperature and number densities obtained by the experiments on the Venera entry probes, Pioneer Venus Orbiter and multi-probe missions in the 1980s. The instruments on the recent Venus Express orbiter mission generated a significant amount of new observational data on the vertical and horizontal structure of the Venus atmosphere from 40 km to about 180 km altitude from April 2006 to November 2014. Many ground based experiments have provided data on the upper atmosphere (90-130 km) temperature structure since the publication of VIRA in 1985. The "Thermal Structure of the Venus Atmosphere" Team was supported by the International Space Studies Institute (ISSI), Bern, Switzerland, from 2013 to 2015 in order to combine and compare the ground-based observations and the VEx observations of the thermal structure as a first step towards generating an updated VIRA model. Results of this comparison are presented in five latitude bins and three local time bins by assuming hemispheric symmetry. The intercomparison of the ground-based and VEx results provides for the first time a consistent picture of the temperature and density structure in the 40 km-180 km altitude range. The Venus Express observations have considerably increased our knowledge of the Venus atmospheric thermal structure above ∼40 km and provided new information above 100 km. There are, however, still observational gaps in latitude and local time above certain regions. Considerable variability in the temperatures and densities is seen above 100 km but certain features appear to be systematically present, such as a succession of warm and cool layers. Preliminary modeling studies support the existence of such layers in agreement with a global scale circulation. The intercomparison focuses on average profiles but some VEx experiments provide sufficient global coverage to identify solar thermal tidal components. The differences between the VEx temperature profiles and the VIRA below 0.1 mbar/95 km are small. There is, however, a clear discrepancy at high latitudes in the 10-30 mbar (70-80 km) range. The VEx observations will also allow the improvement of the empirical models (VTS3 by Hedin et al., 1983 and VIRA by Keating et al., 1985) above 0.03 mbar/100 km, in particular the 100-150 km region where a sufficient observational coverage was previously missing. The next steps in order to define the updated VIRA temperature structure up to 150 km altitude are (1) define the grid on which this database may be provided, (2) fill what is possible with the results of the data intercomparison, and (3) fill the observational gaps. An interpolation between the datasets may be performed by using available General Circulation Models as guidelines. An improved spatial coverage of observations is still necessary at all altitudes, in latitude-longitude and at all local solar times for a complete description of the atmospheric thermal structure, in particular on the dayside above 100 km. New in-situ observations in the atmosphere below 40 km are missing, an altitude region that cannot be accessed by occultation experiments. All these questions need to be addressed by future missions. [less ▲]

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See detailThe Mars atomic oxygen dayglow: predictions based on the OI 297.2 nm MAVEN/IUVS observations
Gkouvelis, Leonardos ULiege; Gérard, Jean-Claude ULiege; Hubert, Benoît ULiege

Conference (2017, June 23)

The oxygen green line at 557.7 nm corresponds to the 1S →1D forbidden transition of the O atom. It shares the same upper level as the 1S→ 3P UV line at 297.2 nm. The green line is a major component of the ... [more ▼]

The oxygen green line at 557.7 nm corresponds to the 1S →1D forbidden transition of the O atom. It shares the same upper level as the 1S→ 3P UV line at 297.2 nm. The green line is a major component of the visible terrestrial dayglow spectrum and accounts for the dominant color of the high-latitude auroral display. The 297.2 nm emission was first detected with spectrometers on board the Mariner missions. It has since has been observed at the limb in the Martian dayglow with the SPICAM (Mars Express) and IUVS (MAVEN) spectrographs. The sources of the 1S excitation in the Mars dayglow are electron impact on O, photodissociation and electron impact dissociation of CO2 and CO and dissociative recombination of O2+ ions. [less ▲]

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See detailJuno, Hubble and James Webb observing Jupiter’s aurora
Grodent, Denis ULiege; Bonfond, Bertrand ULiege; Yao, Zhonghua ULiege et al

Conference (2017, June 15)

Hubble Space Telescope (HST) observations of Jupiter’s aurora, supporting the Juno mission, started on 30 Nov 2016. So far, they successfully covered orbits PJ03 to PJ06. After PJ07 in July 2017, the HST ... [more ▼]

Hubble Space Telescope (HST) observations of Jupiter’s aurora, supporting the Juno mission, started on 30 Nov 2016. So far, they successfully covered orbits PJ03 to PJ06. After PJ07 in July 2017, the HST campaign will be interrupted by a solar avoidance period, preventing any observations from late August to the end of December 2017 (PJ08 to PJ10). The campaign will resume with PJ11 and continue until the end of HST cycle 25 (PJ15). Here, we present a brief summary of the HST data that has been acquired so far. It shows a broad range of auroral morphologies, suggesting that the Juno mission is sampling di ff erent facets of Jupiter’s magnetospheric activity. One should keep in mind that HST will not last forever. We should be ready to switch to the James Webb Telescope and take advantage of the overlap between the HST and JWST missions to prepare a smooth transition. The numerous infrared observations of Jupiter’s aurora obtained from ground based telescopes during Juno and obviously with Juno-JIRAM demonstrate that we can expect much from the tremendous performances of the JWST NIRCam and NIRSpec instruments. [less ▲]

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See detailJuno-UVS observation of the Io footprint during eclipse
Hue, V.; Gladstone; Greathouse et al

Conference (2017, June 15)

The Juno mission offers a unique opportunity to study Jupiter, from its inner structure to its magnetospheric environment. Juno-UVS is a UV spectrograph with a bandpass of 70<lambda<205 mn, designed to ... [more ▼]

The Juno mission offers a unique opportunity to study Jupiter, from its inner structure to its magnetospheric environment. Juno-UVS is a UV spectrograph with a bandpass of 70<lambda<205 mn, designed to characterize Jupiter’s UV emissions. One of the main feature of UVS is its scan mirror, which allows targeting specific UV features that are located +/- 30 ̊ perpendicular to the Juno spin plane. Juno provides a unique vantage point in Jupiter’s system to perform observations otherwise not possible from Earth. During Perijove 3 (PJ time: 11 December 2016 at 17:04 UTC), Io went into eclipse on Dec. 11th from 17:38:43 to 19:52:25 UTC. At that time, Juno was flying over the South Pole and observed the Io footprint from 17:50 to 22:04, with nearly continuous time coverage. Since Juno is spinning at 2 rpm, the Io footprint was observed once every 30 sec. The atmosphere of Io is mostly composed of SO2, with a small contribution of SO, S2, and NaCl. Whether its atmosphere is sublimation driven or supported by the volcanic activity is being controversially debated over decades. Studying the response of Io’s footprint brightness as it enters and leaves eclipse provides a novel method to probe its atmospheric response to a diminution of the solar flux. We will present the observations of this event and how the interaction strength of the interaction between Io’s ionosphere and the magnetosphere of Jupiter evolve during the eclipse. [less ▲]

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See detailConcurrent ultraviolet and infrared observations of the north Jovian aurora during Juno’s first perijove
Gérard, Jean-Claude ULiege; Bonfond, Bertrand ULiege; Gladstone, G.R. et al

Conference (2017, June 15)

The UltraViolet Spectrograph (UVS) and the Jupiter InfraRed Auroral Mapper (JIRAM) observed the polar aurora during the perijove phase of the first Juno orbit (PJ1) on 27 August 2016. The UVS passband ... [more ▼]

The UltraViolet Spectrograph (UVS) and the Jupiter InfraRed Auroral Mapper (JIRAM) observed the polar aurora during the perijove phase of the first Juno orbit (PJ1) on 27 August 2016. The UVS passband includes H2 bands that are directly excited by collisions of auroral electrons with H2. The JIRAM L-band imager includes some of the brightest H3+ features between 3.3 and 3.6 μ m. The intensity if this IR emission depends on both the column density of H3+ and the temperature in the emitting region. A series of spatial scans obtained every 30 s is used to build up images of the polar regions. JIRAM’s spatial resolution was about 100 km/pixel during most of the observations reported here while UVS has a substantially lower resolution (about 250 km/pixel). Concurrent observations were obtained during about 70 min in the north. We present a set of simultaneous ultraviolet and infrared images and point out similarities and di ff erences in their morphology and brightness distribution. The time evolution in the two spectral domains will be described and interpreted in terms of energy of the auroral electrons, time history of the precipitation and lifetime of the H3+ ions. Ultraviolet color ratio maps visualize the spatial distribution of the characteristic energy of the primary auroral electrons. Other supporting information is provided by the H3+ temperatures and column density maps derived from the analysis of JIRAM spectra covering the 2-5 μm interval. [less ▲]

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See detailNorth and South: Simultaneous observations of both Jovian poles from Juno and the Hubble Space Telescope
Bonfond, Bertrand ULiege; Gladstone, George R.; Grodent, Denis ULiege et al

Poster (2017, June 15)

On its elongated orbit, Juno flies over the poles of Jupiter every 53.5 days. The few hours before and after the perijove offer unique opportunities to observe the whole polar region from close distance ... [more ▼]

On its elongated orbit, Juno flies over the poles of Jupiter every 53.5 days. The few hours before and after the perijove offer unique opportunities to observe the whole polar region from close distance. However, Juno’s instruments can only observe one hemisphere at a time. Fortunately, the Hubble Space Telescope points its 2.4 m mirror toward the opposite hemisphere during some of these time intervals, providing truly simultaneous observations of both poles. We compare observations from Juno-UVS with Far-UV imaging sequences from the Hubble’s Space Telescope Imaging Spectrograph (STIS). Juno-UVS acquires spectrally resolved images of 17 ms exposure every 30 s Juno spin in the 70-205 nm wavelength range, while STIS can acquire about 270 consecutive 10 s images per HST orbit in the 130-160 nm range, but without any spectral resolution. Despite some differences, these datasets are similar enough in terms of spectral coverage, temporal and spatial resolution to allow direct comparisons. On Jupiter, the magnetic field is highly asymmetric and displays significant localized anomalies. Furthermore, most processes leading to auroral emissions depend on the magnetic field magnitude, either in the equatorial plane, in the acceleration regions, or in the upper atmosphere. Investigating morphological and brightness discrepancies between the two hemispheres provides precious clues on the current systems flowing in the magnetosphere and on the charged particles acceleration mechanisms. [less ▲]

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See detailAn Overview of Juno-UVS Observations of Jupiter’s Auroras through Perijove 6
Gladstone, G. R.; Versteeg, M. H.; Greathouse, T. K. et al

Conference (2017, June 14)

Currently, Juno’s Ultraviolet Spectrograph (UVS) has observed the Jovian aurora during five perijove passes. On each pass, UVS observes Jupiter for 10 hours centered on closest approach in a series of ... [more ▼]

Currently, Juno’s Ultraviolet Spectrograph (UVS) has observed the Jovian aurora during five perijove passes. On each pass, UVS observes Jupiter for 10 hours centered on closest approach in a series of swaths, with one swath per 30s spin of the Juno spacecraft. During this time the range to the aurora drops from 6 RJ to 0.3 RJ or less in the north (and reverses this in the south), so that spatial resolution and coverage change dramatically. The UVS scan mirror is used to target di ff erent features, as the auroral regions are generally much larger than UVS’s 7-degree long slit can accommodate in a single swath. Typically, the scan mirror position is changed every 2 -5 Juno spins, to track specific targets or just raster across the entire auroral region. Since UVS only observes any particular location for 17 ms/swath, the series of swaths provide snapshots of ultraviolet auroral brightness and color. A variety of forms and activity levels are represented in this data set, and many have been described before with HST observations, but are seen here with higher spatial resolution. One interesting result is that in false color images (where RGB colors are assigned to long, medium, and short UV wavelengths, respectively), the emission morphology often alternates red and blue, in a way similar to patterns expected of large scale current systems. Further results which emerge as the UVS data are compared with data from the other Juno auroral instruments will also be presented. [less ▲]

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See detailAdvances on the magnetospheric dynamics of Saturn revealed from UVIS/Cassini auroral observations during the Grand finale phase of the mission
Radioti, Aikaterini ULiege; Grodent, Denis ULiege; Yao, Zhonghua ULiege et al

Poster (2017, June 13)

Auroral observations are a powerful tool to study the magnetospheric processes as they provide a ‘global picture’ of the magnetosphere at once. Here we present UVIS/Cassini auroral observations during the ... [more ▼]

Auroral observations are a powerful tool to study the magnetospheric processes as they provide a ‘global picture’ of the magnetosphere at once. Here we present UVIS/Cassini auroral observations during the Grand Finale phase of the mission. As the spacecraft approaches closely Saturn’s poles it offers an unprecedented view of the dayside and nightside auroral regions. Auroral observations which have been recently analysed from the beginning of the F-ring orbits reveal dusk/midnight arcs with a large latitudinal extent, suggesting that they are related to a source region extending from the outer to middle/inner magnetosphere. Their presence is shown to initiate dawn auroral enhancements and poleward expansions which display irregular shaped structures. Following the terrestrial example, we suggest that at Saturn the dusk/midnight arcs (possible signatures of planetward propagating plasma flows) might have caused a magnetospheric reconfiguration event, which is manifested as enhancement and poleward expansion of the dawn aurora. While the aforementioned discussion provides only the results based on the early Cassini F-ring orbits, we will also present auroral observations from the upcoming orbits with conjugate in-situ measurements. In particular, we will discuss the advances on magnetospheric dynamics at Saturn through the eyes of UVIS, during the final months of the mission. [less ▲]

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See detailMorphology of the UV aurorae Jupiter during Juno’s first perijove observations
Bonfond, Bertrand ULiege; Gladstone, G. R.; Grodent, Denis ULiege et al

in Geophysical Research Letters (2017)

On 27 August 2016, the NASA Juno spacecraft performed its first close-up observations of Jupiter during its perijove. Here we present the UV images and color ratio maps from the Juno-ultraviolet ... [more ▼]

On 27 August 2016, the NASA Juno spacecraft performed its first close-up observations of Jupiter during its perijove. Here we present the UV images and color ratio maps from the Juno-ultraviolet spectrometer UV imaging spectrograph acquired at that time. Data were acquired during four sequences (three in the north, one in the south) from 5:00 UT to 13:00 UT. From these observations, we produced complete maps of the Jovian aurorae, including the nightside. The sequence shows the development of intense outer emission outside the main oval, first in a localized region (255 ∘ –295 ∘ System III longitude) and then all around the pole, followed by a large nightside protrusion of auroral emissions from the main emission into the polar region. Some localized features show signs of differential drift with energy, typical of plasma injections in the middle magnetosphere. Finally, the color-ratio map in the north shows a well-defined area in the polar region possibly linked to the polar cap. [less ▲]

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See detailLargest Electron Differential Energy Flux Observed at Mars, 2004-2016
Frahm, R.A.; Winninham, J.D.; Coates, A.J. et al

Conference (2017, May 17)

The shape of the largest DEF electron spectrum is similar at Mars and Venus. The shape of the largest DEF electron spectra at Mars and Venus is similar to the electron spectrum detected during the times ... [more ▼]

The shape of the largest DEF electron spectrum is similar at Mars and Venus. The shape of the largest DEF electron spectra at Mars and Venus is similar to the electron spectrum detected during the times SPICAM detects “auroral” enhanced signatures. Since the magnetic field at Mars is chaotic, the largest DEF electron spectrum could be magnetically directed from the dayside to the nightside where it could precipitate causing the same “auroral” signature seen by SPICAM. [less ▲]

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See detailThe Jovian UV aurorae as seen by Juno-UVS
Bonfond, Bertrand ULiege; Gladstone, Randy; Grodent, Denis ULiege et al

Conference (2017, April 26)

The Juno spacecraft was inserted in orbit around Jupiter on July 4th 2016. Its highly elongated polar orbit brings it <5000 km above the cloud tops every 53,5 days, allowing spectacular and unprecedented ... [more ▼]

The Juno spacecraft was inserted in orbit around Jupiter on July 4th 2016. Its highly elongated polar orbit brings it <5000 km above the cloud tops every 53,5 days, allowing spectacular and unprecedented views of its polar aurorae. The Juno-UVS instrument is an imaging spectrograph observing perpendicularly to the Juno spin axis. It is equipped with a moving scan mirror at the entrance of the instrument that allows the field of view to be directed up to +/-30° away from the spin plane. The 70-205 nm bandpass comprises key UV auroral emissions such as the H2 bands and the H Lyman alpha line, as well as hydrocarbon absorption bands. We present polar maps of the aurorae at Jupiter for the first three first few periapses. These maps offer the first high resolution observations of the night-side aurorae. We will discuss the observed auroral morphology, including the satellite footprints, the outer emissions, the main emission and the polar emissions. We will also show maps of the color ratio, comparing the relative intensity of wavelengths subject to different degrees of absorption by CH4. Such measurements directly relate to the energy of the precipitating particles, since the more energetic the particles, the deeper they penetrate and the stronger the resulting methane absorption. For example, we will show evidence of longitudinal shifts between the brightness peaks and color ratio peaks in several auroral features. Such shifts may be interpreted as the result of the differential particle drift in plasma injection signatures. [less ▲]

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See detailHST observations of Jupiter's UV aurora during Juno's orbits PJ03, PJ04 and PJ05
Grodent, Denis ULiege; Gladstone, G Randall; Clarke, John T. et al

Poster (2017, April)

The intense ultraviolet auroral emissions of Jupiter are currently being monitored in the frame of a large Hubble Space Telescope (HST) program meant to support the NASA Juno prime mission. The present ... [more ▼]

The intense ultraviolet auroral emissions of Jupiter are currently being monitored in the frame of a large Hubble Space Telescope (HST) program meant to support the NASA Juno prime mission. The present study addresses the three first Juno orbits (PJ03, 04 and 05) during which HST obtained parallel observations. These three campaigns basically consist of a 2-week period bracketing the time of Juno’s closest approach of Jupiter (CA). At least one HST visit is scheduled every day during the week before and the week following CA. During the ∼12-hour period centered on CA and depending on observing constraints, several HST visits are programmed in order to obtain as many simultaneous observations with Juno-UVS as possible. In addition, at least one HST visit is obtained near Juno’s apojove, when UVS is continuously monitoring Jupiter’s global auroral power, without spatial resolution, for about 12 hours. We are using the Space Telescope Imaging Spectrograph (STIS) in time-tag mode in order to provide spatially resolved movies of Jupiter’s highly dynamic aurora with timescales ranging from seconds to several days. We discuss the preliminary exploitation of the HST data and present these results in such a way as to provide a global magnetospheric context for the different Juno instruments studying Jupiter’s magnetosphere, as well as for the numerous ground based and space based observatories participating to the Juno mission. [less ▲]

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See detailMagnetic reconnection during steady magnetospheric convection and other magnetospheric modes
Hubert, Benoît ULiege; Gérard, Jean-Claude ULiege; Milan, Steve E. et al

in Annales Geophysicae (2017), 35

We use remote sensing of the proton aurora with the IMAGE-FUV SI12 (Imager for Magnetopause to Aurora Global Exploration-Far Ultraviolet-Spectrographic Imaging at 121.8 nm) instrument and radar ... [more ▼]

We use remote sensing of the proton aurora with the IMAGE-FUV SI12 (Imager for Magnetopause to Aurora Global Exploration-Far Ultraviolet-Spectrographic Imaging at 121.8 nm) instrument and radar measurements of the ionospheric convection from the SuperDARN (Super Dual Aurora Radar Network) facility to estimate the open magnetic flux in the Earth's magnetosphere and the reconnection rates at the dayside magnetopause and in the magnetotail during intervals of steady magnetospheric convection (SMC). We find that SMC intervals occur with relatively high open magnetic flux (average ˜ 0.745 GWb, standard deviation ˜ 0.16 GWb), which is often found to be nearly steady, when the magnetic flux opening and closure rates approximately balance around 55 kV on average, with a standard deviation of 21 kV. We find that the residence timescale of open magnetic flux, defined as the ratio between the open magnetospheric flux and the flux closure rate, is roughly 4 h during SMCs. Interestingly, this number is approximately what can be deduced from the discussion of the length of the tail published by Dungey (1965), assuming a solar wind speed of ˜ 450 km s[SUP]-1[/SUP]. We also infer an enhanced convection velocity in the tail, driving open magnetic flux to the nightside reconnection site. We compare our results with previously published studies in order to identify different magnetospheric modes. These are ordered by increasing open magnetic flux and reconnection rate as quiet conditions, SMCs, substorms (with an important overlap between these last two) and sawtooth intervals. [less ▲]

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See detailThe Martian diffuse aurora: a model of ultraviolet and visible emissions
Gérard, Jean-Claude ULiege; Soret, Lauriane ULiege; Shematovich, V.I. et al

in Icarus (2017), 288

A new type of Martian aurora, characterized by an extended spatial distribution, an altitude lower than the discrete aurora and electron precipitation up to 200 keV has been observed following solar ... [more ▼]

A new type of Martian aurora, characterized by an extended spatial distribution, an altitude lower than the discrete aurora and electron precipitation up to 200 keV has been observed following solar activity on several occasions from the MAVEN spacecraft. We describe the results of Monte Carlo simulations of the production of several ultraviolet and violet auroral emissions for initial electron energies extending from 0.25 to 200 keV. These include the CO2+ ultraviolet doublet (UVD) at 288.3 and 289.6 nm and the Fox–Duffendack–Barker (FDB) bands, CO Cameron and Fourth Positive bands, OI 130.4 and 297.2 nm and CI 156.1 nm and 165.7 nm multiplets. We calculate the nadir and limb production rates of several of these emissions for a unit precipitated energy flux. Our results indicate that electrons in the range 50-200 keV produce maximum CO2+ UVD emission below 75 km, in agreement with the MAVEN observations. We calculate the efficiency of photon production per unit precipitated electron power. The strongest emissions are the CO2+ FDB, UVD and CO Cameron bands and the oxygen mission at 297.2 nm. The metastable a 3Π state which radiates the Cameron bands is deactivated by collisions below about 110 km. As a consequence, we show that the Cameron band emission is expected to peak at a higher altitude than the CO2+ UVD and FDB bands. Collisional quenching also causes the intensity ratio of the CO2+ UVD to CO Cameron bands to increase below ∼100 km in the energetic diffuse aurora. [less ▲]

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See detailGlobal Simulation of UV Atmospheric Emissions
González-Galindo, F.; López-Valverde, M. A.; Forget, F. et al

Conference (2017, January 17)

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See detailThree Types of Aurora observed by MAVEN/IUVS: Implications for Mars’ upper Atmosphere Energy Budget
Connour; Schneider; Jain et al

Poster (2017, January 17)

Detailed reference viewed: 30 (5 ULiège)