References of "Journal of Geophysical Research. Space Physics"
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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 detailCalibration and testing of wide-field UV instruments
Frey, Harald; Mende, Stephen; Loicq, Jerôme ULiege et al

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

As with all optical systems the calibration of wide-field ultraviolet (UV) systems includes three main areas: sensitivity, imaging quality, and imaging capability. The one thing that makes UV calibrations ... [more ▼]

As with all optical systems the calibration of wide-field ultraviolet (UV) systems includes three main areas: sensitivity, imaging quality, and imaging capability. The one thing that makes UV calibrations difficult is the need for working in vacuum substantially extending the required time and effort compared to visible systems. In theory a ray tracing and characterization of each individual component of the optical system (mirrors, windows, and grating) should provide the transmission efficiency of the combined system. However, potentially unknown effects (contamination, misalignment, and measurement errors) can make the final error too large and unacceptable for most applications. Therefore, it is desirable to test and measure the optical properties of the whole system in vacuum and compare the overall response to the response of a calibrated photon detector. A proper comparison then allows the quantification of individual sources of uncertainty and ensures that the whole instrument performance is within acceptable tolerances or pinpoints which parts fail to meet requirements. Based on the experience with the IMAGE Spectrographic Imager, the Wide-band Imaging Camera, and the ICON Far Ultraviolet instruments, we discuss the steps and procedures for the proper radiometric sensitivity and passband calibration, spot size, imaging distortions, flatfield, and field of view determination. [less ▲]

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See detailThe structure and variability of Mars dayside thermosphere from MAVEN NGIMS and IUVS measurements: Seasonal and solar activity trends in scale heights and temperatures
Bougher, S. W.; Roeten, K. J.; Olsen, K. et al

in Journal of Geophysical Research. Space Physics (2017)

Mars dayside thermospheric temperature and scale height trends were examined using measurements from the Neutral Gas Ion Mass Spectrometer (NGIMS) and the Imaging Ultraviolet Spectrograph (IUVS) on the ... [more ▼]

Mars dayside thermospheric temperature and scale height trends were examined using measurements from the Neutral Gas Ion Mass Spectrometer (NGIMS) and the Imaging Ultraviolet Spectrograph (IUVS) on the Mars Atmosphere Volatile EvolutioN (MAVEN) spacecraft. Average scale heights (over 150-180 km for solar zenith angles ≤75°) from several different sampling periods were obtained from each instrument. NGIMS and IUVS scale height trends were found to be in good agreement, with both showing scale heights decreasing after perihelion and reaching a low value near aphelion (13.6 to 9.4 km). Between these two seasonal extremes, the temperature decreased by ∼70 K (from 240 to 170 K). These trends were also analyzed with respect to the changing solar flux reaching the planet, using the Lyman alpha irradiance measured by the Extreme Ultraviolet Monitor (EUVM) on MAVEN. Scale heights responded strongly to the changing solar flux. During this part of the MAVEN mission (October 2014 to May 2016), it was concluded that over longer timescales (at least several months), dayside thermospheric temperatures are chiefly driven by changing solar forcing, although it is the effects of changing heliocentric distance rather than changing solar activity which seem to have the greatest impact. Furthermore, effects of solar forcing were not observed on shorter timescales (less than a month), suggesting local wave effects may dominate solar forcing on these timescales. Finally, temperatures from two NGIMS sampling periods were compared to temperatures from the Mars Global Ionosphere-Thermosphere Model (M-GITM) and found to be in good agreement. © 2017. American Geophysical Union. All Rights Reserved. [less ▲]

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See detailNitric Oxide Nightglow and Martian Mesospheric Circulation from MAVEN/IUVS Observations and LMD-MGCM Predictions
Stiepen, Arnaud ULiege; Jain; Schneider et al

in Journal of Geophysical Research. Space Physics (2017)

We report results from a study of nitric oxide nightglow over the north- ern hemisphere of Mars during winter, the southern hemisphere during fall equinox and equatorial latitudes during summer in the ... [more ▼]

We report results from a study of nitric oxide nightglow over the north- ern hemisphere of Mars during winter, the southern hemisphere during fall equinox and equatorial latitudes during summer in the northern hemisphere based on observations of the delta and gamma bands between 190 and 270 nm by the Imaging UltraViolet Spectrograph (IUVS) on the MAVEN spacecraft. The emission reveals recombination of N and O atoms dissociated on the day- side of Mars and transported to the nightside. We characterize the bright- ness (from 0.2 to 30 kR) and altitude (from 40 to 115 km) of the NO night- glow layer, as well as its topside scale height (mean of 11 km). We show the possible impact of atmospheric waves forcing longitudinal variability, asso- ciated with an increased brightness by a factor 3 in the 140 - 200 longitude region in the northern hemisphere winter and in the -102 to -48 longitude region at summer. Such impact to the NO nightglow at Mars was not seen before. Quantitative comparison with calculations of the LMD-MGCM (Lab- oratoire de M et eorologie Dynamique - Global Circulation Model) suggests that the model globally reproduces the trends of the NO nightglow emission and its seasonal variation, but also indicates large discrepancies (up to a fac- tor 50 fainter in the model) in northern winter at low to mid-latitudes. This suggests that the predicted transport is too e cient towards the night win- ter pole in the thermosphere by 20 latitude north. [less ▲]

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See detailStagnation of Saturn's auroral emission at noon
Radioti, Aikaterini ULiege; Grodent, Denis ULiege; Gérard, Jean-Claude ULiege et al

in Journal of Geophysical Research. Space Physics (2017)

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See detailVariability of D and H in the Martian Upper Atmosphere Observed with the MAVEN IUVS Echelle Channel
Clarke, J. T.; Mayyasi, M.; Bhattacharyya, D. et al

in Journal of Geophysical Research. Space Physics (2017)

The MAVEN IUVS instrument contains an echelle spectrograph channel designed to measure D and H Ly α emissions from the upper atmosphere of Mars. This channel has successfully recorded both emissions ... [more ▼]

The MAVEN IUVS instrument contains an echelle spectrograph channel designed to measure D and H Ly α emissions from the upper atmosphere of Mars. This channel has successfully recorded both emissions, which are produced by resonant scattering of solar emission, over the course of most of a martian year. The fundamental purpose of these measurements is to understand the physical principles underlying the escape of H and D from the upper atmosphere into space, and thereby to relate present-day measurements of an enhanced HDO/H2O ratio in the bulk atmosphere to the water escape history of Mars. Variations in these emissions independent of the solar flux reflect changes in the density and/or temperature of the species in the upper atmosphere. The MAVEN measurements show that the densities of both H and D vary by an order of magnitude over a martian year, and not always in synch with each other. This discovery has relevance to the processes by which H and D escape into space. One needs to understand the controlling factors to be able to extrapolate back in time to determine the water escape history from Mars at times when the atmosphere was thicker, when the solar flux and solar wind were stronger, etc. Further measurements will be able to identify the specific controlling factors for the large changes in H and D, which likely result in large changes in the escape fluxes of both species. [less ▲]

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See detailPulsations of the polar cusp aurora at Saturn
Palmaerts, Benjamin ULiege; Radioti, Aikaterini ULiege; Roussos, E. et al

in Journal of Geophysical Research. Space Physics (2016), 121

The magnetospheric cusp is a region connecting the interplanetary environment to the ionosphere and enabling solar wind particles to reach the ionosphere. We report the detection of several isolated high ... [more ▼]

The magnetospheric cusp is a region connecting the interplanetary environment to the ionosphere and enabling solar wind particles to reach the ionosphere. We report the detection of several isolated high-latitude auroral emissions with the Ultraviolet Imaging Spectrograph of the Cassini spacecraft. We suggest that these auroral spots, located in the dawn-to-noon sector and poleward of the main emission, are the ionospheric signatures of the magnetospheric cusp, in agreement with some previous observations with the Hubble Space Telescope. The high-latitude cusp auroral signature has been associated with high-latitude lobe reconnection in the presence of a southward interplanetary magnetic field. The occurrence rate of the polar cusp aurora suggests that lobe reconnection is frequent at Saturn. Several auroral imaging sequences reveal a quasiperiodic brightening of the polar cusp aurora with a period in the range of 60 to 70 min. Similar pulsations in the energetic electron fluxes and in the azimuthal component of the magnetic field are simultaneously observed by Cassini instruments, suggesting the presence of field-aligned currents. Pulsed dayside magnetopause reconnection is a likely common triggering process for the cusp auroral brightenings at Saturn and the quasiperiodic pulsations in the high-latitude energetic electron fluxes. [less ▲]

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See detailAnalytical estimate for low-altitude ENA emissivity
Goldstein, J.; Bisikalo, D.V.; Shematovich, V.I. et al

in Journal of Geophysical Research. Space Physics (2016), 121(2), 1167-1191

We formulate the first analytical model for energetic neutral atom (ENA) emissivity that partially corrects for the global viewing geometry dependence of low-altitude emissions (LAEs) observed by Two Wide ... [more ▼]

We formulate the first analytical model for energetic neutral atom (ENA) emissivity that partially corrects for the global viewing geometry dependence of low-altitude emissions (LAEs) observed by Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS). The emissivity correction requires the pitch angle distribution (PAD) and geophysical location of low-altitude ENAs. To estimate PAD, we create an energy-dependent analytical model, based on a Monte Carlo simulation. We account for energy binning by integrating model PAD over each energy bin. We account for finite angular pixels by computing emissivity as an integral over the pitch angle range sampled by the pixel. We investigate location uncertainty in TWINS pixels by performing nine variations of the emissivity calculation. Using TWINS 2 ENA imaging data from 1131 to 1145 UT on 6 April 2010, we derive emissivity-corrected ion fluxes for two angular pixel sizes: 4° and 1°. To evaluate the method, we compare TWINS-derived ion fluxes to simultaneous in situ data from the National Oceanic and Atmospheric Administration (NOAA) 17 satellite. The TWINS-NOAA agreement for emissivity-corrected flux is improved by up to a factor of 7, compared to uncorrected flux. The highest 1° pixel fluxes are a factor of 2 higher than for 4° pixels, consistent with pixel-derived fluxes that are artificially low because subpixel structures are smoothed out, and indicating a possible slight advantage to oversampling the instrument-measured LAE signal. Both TWINS and NOAA ion fluxes decrease westward of 2000 magnetic local time. The TWINS-NOAA comparison indicates that the global ion precipitation oval comprises multiple smaller-scale (3-5° of latitude) structures. [less ▲]

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See detailAuroral evidence of radial transport at Jupiter during January 2014
Gray, R. L.; Badman, S. V.; Bonfond, Bertrand ULiege et al

in Journal of Geophysical Research. Space Physics (2016)

We present Jovian auroral observations from the 2014 January Hubble Space Telescope (HST) campaign and investigate the auroral signatures of radial transport in the magnetosphere alongside contemporaneous ... [more ▼]

We present Jovian auroral observations from the 2014 January Hubble Space Telescope (HST) campaign and investigate the auroral signatures of radial transport in the magnetosphere alongside contemporaneous radio and Hisaki EUV data. HST FUV auroral observations on day 11 show, for the first time, a significantly superrotating polar spot poleward of the main emission on the dawnside. The spot transitions from the polar to main emission region in the presence of a locally broad, bright dawnside main emission feature and two large equatorward emission features. Such a configuration of the main emission region is also unreported to date. We interpret the signatures as part of a sequence of inward radial transport processes. Hot plasma inflows from tail reconnection are thought to flow planetward and could generate the superrotating spot. The main emission feature could be the result of flow shears from prior hot inflows. Equatorward emissions are observed. These are evidence of hot plasma injections in the inner magnetosphere. The images are thought to be part of a prolonged period of reconnection. Radio emissions measured by Wind suggest that hectometric (HOM) and non-Io decametric (DAM) signatures are associated with the sequence of auroral signatures, which implies a global magnetospheric disturbance. The reconnection and injection interval can continue for several hours. [less ▲]

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See detailWhat controls the local time extent of flux transfer events?
Milan, S. E.; Imber, S. M.; Carter, J. A. et al

in Journal of Geophysical Research. Space Physics (2016), 121

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See detailNonthermal radiative transfer of oxygen 98.9 nm ultraviolet emission: Solving an old mystery
Hubert, Benoît ULiege; Gérard, Jean-Claude; Shematovich, Valery I. et al

in Journal of Geophysical Research. Space Physics (2015), 120

Sounding rocket measurements conducted in 1988 under high solar activity conditions revealed that the intensity of thermospheric OI emissions at 98.9 nm present an anomalous vertical profile, showing ... [more ▼]

Sounding rocket measurements conducted in 1988 under high solar activity conditions revealed that the intensity of thermospheric OI emissions at 98.9 nm present an anomalous vertical profile, showing exospheric intensities much higher than expected from radiative transfer model results, which included the known sources of excited oxygen. All attempts based on modeling of the photochemical processes and radiative transfer were unable to account for the higher than predicted brightnesses. More recently, the SOHO-SUMER instrument measured the UV solar flux at high spectral resolution, revealing the importance of a significant additional source of oxygen emission at 98.9 nm that had not been accounted for before. In this study, we simulate the radiative transfer of the OI-98.9 nm multiplet, including the photochemical sources of excited oxygen, the resonant scattering of solar photons, and the effects of non-thermal atoms, i.e. a population of fast-moving oxygen atoms in excess of the Maxwellian distribution. Including resonance scattering of the 98.9 nm solar multiplet, we find good agreement with the previous sounding rocket observation. The inclusion of a nonthermal oxygen population with a consistent increase of the total density produces a larger intensity at high altitude that apparently better accounts for the observation, but such a correction cannot be demonstrated given the uncertainties of the observations. A good agreement between model and sounding rocket observation is also found with the triplet at 130.4 nm. We further investigate the radiative transfer of the OI-98.9 nm multiplet, and the oxygen emissions at 130.4 and 135.6 nm using observations from the STP78-1 satellite. We find a less satisfying agreement between the model and the STP78-1 data that can be accounted for by scaling the modelled intensity within a range acceptable given the uncertainties on the STP78-1 absolute calibration. [less ▲]

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See detailMagnetosphere-ionosphere mapping at Jupiter: Quantifying the effects of using different internal field models
Vogt, Marissa; Bunce, Emma; Kivelson, Margaret et al

in Journal of Geophysical Research. Space Physics (2015), 120

The lack of global field models accurate beyond the inner magnetosphere (<30 RJ) makes it difficult to relate Jupiter's polar auroral features to magnetospheric source regions. We recently developed a ... [more ▼]

The lack of global field models accurate beyond the inner magnetosphere (<30 RJ) makes it difficult to relate Jupiter's polar auroral features to magnetospheric source regions. We recently developed a model that maps Jupiter's equatorial magnetosphere to the ionosphere using a flux equivalence calculation that requires equal flux at the equatorial and ionospheric ends of flux tubes. This approach is more accurate than tracing field lines in a global field model but only if it is based on an accurate model of Jupiter's internal field. At present there are three widely used internal field models—Voyager Io Pioneer 4 (VIP4), the Grodent Anomaly Model (GAM), and VIP Anomaly Longitude (VIPAL). The purpose of this study is to quantify how the choice of an internal field model affects the mapping of various auroral features using the flux equivalence calculation. We find that different internal field models can shift the ionospheric mapping of points in the equatorial plane by several degrees and shift the magnetospheric mapping to the equator by ~30 RJ radially and by less than 1 h in local time. These shifts are consistent with differences in how well each model maps the Ganymede footprint, underscoring the need for more accurate Jovian internal field models. We discuss differences in the mapping of specific auroral features and the size and location of the open/closed field line boundary. Understanding these differences is important for the continued analysis of Hubble Space Telescope images and in planning for Juno's arrival at Jupiter in 2016. [less ▲]

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See detailAuroral spirals at Saturn
Radioti, Aikaterini ULiege; Grodent, Denis ULiege; Gérard, Jean-Claude ULiege et al

in Journal of Geophysical Research. Space Physics (2015)

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See detailConcurrent observations of ultraviolet aurora and energetic electron precipitation with Mars Express
Gérard, Jean-Claude ULiege; Soret, Lauriane ULiege; Libert, Ludivine ULiege et al

in Journal of Geophysical Research. Space Physics (2015)

The database of the Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) instrument between late January 2004 and Mars 2014 has been searched to identify signatures ... [more ▼]

The database of the Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) instrument between late January 2004 and Mars 2014 has been searched to identify signatures of CO Cameron and CO<inf>2</inf>+ doublet ultraviolet auroral emissions. This study has almost doubled the number of auroral detections based on SPICAM spectra. Auroral emissions are located in the vicinity of the statistical boundary between open and closed field lines. From a total of 113 nightside orbits with SPICAM pointing to the nadir in the region of residual magnetic field, only nine nightside orbits show confirmed auroral signatures, some with multiple detections along the orbital track, leading to a total of 16 detections. The mean energy of the electron energy spectra measured during concurrent Analyzer of Space Plasma and Energetic Atoms/Electron Spectrometer observations ranges from 150 to 280eV. The ultraviolet aurora may be displaced poleward or equatorward of the region of enhanced downward electron energy flux by several tens of seconds and shows no proportionality with the electron flux at the spacecraft altitude. The absence of further UV auroral detection in regions located along crustal magnetic field structures where occasional aurora has been observed indicates that the Mars aurora is a time-dependent feature. These results are consistent with the scenario of acceleration of electrons by transient parallel electric field along semiopen magnetic field lines. © 2015. American Geophysical Union. All Rights Reserved. [less ▲]

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See detailTransient small-scale structure in the main auroral emission at Jupiter
Palmaerts, Benjamin ULiege; Radioti, Aikaterini ULiege; Grodent, Denis ULiege et al

in Journal of Geophysical Research. Space Physics (2014), 119

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See detailMapping the electron energy in Jupiter’s aurora: Hubble spectral observations
Gérard, Jean-Claude ULiege; Bonfond, Bertrand ULiege; Grodent, Denis ULiege et al

in Journal of Geophysical Research. Space Physics (2014), 119

Far ultraviolet spectral observations have been made with the Hubble Space Telescope in the time-tag mode using the Space Telescope Imaging Spectrograph (STIS) long slit. The telescope was slewed in such ... [more ▼]

Far ultraviolet spectral observations have been made with the Hubble Space Telescope in the time-tag mode using the Space Telescope Imaging Spectrograph (STIS) long slit. The telescope was slewed in such a way that the slit projection scanned from above the polar limb down to midlatitudes, allowing us to build up the first spectral maps of the FUV Jovian aurora. The shorter wavelengths are partly absorbed by the methane layer overlying part of the auroral emission layer. The long-wavelength intensity directly reflects the precipitated energy flux carried by the auroral electrons. Maps of the intensity ratio of the two spectral regions have been obtained by combining spectral emissions in two wavelength ranges. They show that the amount of absorption by methane varies significantly between the different components of the aurora and inside the main emission region. Some of the polar emissions are associated with the hardest precipitation, although the auroral regions of strong electron precipitation do not necessarily coincide with the highest electron energies. Outputs from an electron transport model are used to create maps of the distribution of the characteristic electron energies. Using model atmospheres adapted to auroral conditions, we conclude that electron energies range between a few tens to several hundred keV. Comparisons of derived energies are in general agreement with those calculated from magnetosphere-ionosphere coupling models, with values locally exceeding the standard model predictions. These results will provide useful input for three-dimensional modeling of the distribution of particle heat sources into the high-latitude Jovian upper atmosphere. [less ▲]

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See detailCassini nightside observations of the oscillatory motion of Saturn's northern auroral oval
Bunce, E. J.; Grodent, Denis ULiege; Jinks, S. L. et al

in Journal of Geophysical Research. Space Physics (2014), 119

recent years we have benefitted greatly from the first in-orbit multi-wavelength images of Saturn's polar atmosphere from the Cassini spacecraft. Specifically, images obtained from the Cassini UltraViolet ... [more ▼]

recent years we have benefitted greatly from the first in-orbit multi-wavelength images of Saturn's polar atmosphere from the Cassini spacecraft. Specifically, images obtained from the Cassini UltraViolet Imaging Spectrograph (UVIS) provide an excellent view of the planet's auroral emissions, which in turn give an account of the large-scale magnetosphere-ionosphere coupling and dynamics within the system. However, obtaining near-simultaneous views of the auroral regions with in situ measurements of magnetic field and plasma populations at high latitudes is more difficult to routinely achieve. Here we present an unusual case, during Revolution 99 in January 2009, where UVIS observes the entire northern UV auroral oval during a 2 h interval while Cassini traverses the magnetic flux tubes connecting to the auroral regions near 21 LT, sampling the related magnetic field, particle, and radio and plasma wave signatures. The motion of the auroral oval evident from the UVIS images requires a careful interpretation of the associated latitudinally "oscillating" magnetic field and auroral field-aligned current signatures, whereas previous interpretations have assumed a static current system. Concurrent observations of the auroral hiss (typically generated in regions of downward directed field-aligned current) support this revised interpretation of an oscillating current system. The nature of the motion of the auroral oval evident in the UVIS image sequence, and the simultaneous measured motion of the field-aligned currents (and related plasma boundary) in this interval, is shown to be related to the northern hemisphere magnetosphere oscillation phase. This is in agreement with previous observations of the auroral oval oscillatory motion. [less ▲]

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See detailJupiter's equatorward auroral features: possible signatures of magnetospheric injections
Dumont, Maïté ULiege; Grodent, Denis ULiege; Radioti, Aikaterini ULiege et al

in Journal of Geophysical Research. Space Physics (2014)

The present study investigates the characteristics of ultraviolet auroral features located equatorward of the main emission appearing in Hubble Space Telescope images of the northern and southern Jovian ... [more ▼]

The present study investigates the characteristics of ultraviolet auroral features located equatorward of the main emission appearing in Hubble Space Telescope images of the northern and southern Jovian hemispheres obtained in 2000-2007. On average, one feature is observed every day, but several auroral structures are occasionally seen over a wide range of local times in the same image. Several properties of these features are analyzed, such as their location, emitted power and lifetime. Additionally, we magnetically map the auroral features to the equatorial plane using the VIPAL model in order to compare their observed properties with those of magnetospheric injections detected by the Galileo spacecraft. The equatorward auroral features show up between the Io footpath and the main auroral emission, at all System III longitudes, in agreement with Galileo measurements. Moreover, we compare the magnetic flux associated with these features with estimates of the out-going flux related to the radial transport of plasma in the Jovian magnetosphere and we find that they could account for at least one third of this flux. This comparative study shows that the auroral features under study are most probably related to magnetospheric injections and thus sheds light on the processes involved in the magnetosphere-ionosphere dynamics. [less ▲]

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See detailMultispectral simultaneous diagnosis of Saturn's aurorae throughout a planetary rotation
Lamy, L.; Prangé, R.; Pryor, W. et al

in Journal of Geophysical Research. Space Physics (2013), 118

From 27 to 28 January 2009, the Cassini spacecraft remotely acquired combined observations of Saturn's southern aurorae at radio, ultraviolet, and infrared wavelengths, while monitoring ion injections in ... [more ▼]

From 27 to 28 January 2009, the Cassini spacecraft remotely acquired combined observations of Saturn's southern aurorae at radio, ultraviolet, and infrared wavelengths, while monitoring ion injections in the middle magnetosphere from energetic neutral atoms. Simultaneous measurements included the sampling of a full planetary rotation, a relevant timescale to investigate auroral emissions driven by processes internal to the magnetosphere. In addition, this interval coincidentally matched a powerful substorm-like event in the magnetotail, which induced an overall dawnside intensification of the magnetospheric and auroral activity. We comparatively analyze this unique set of measurements to reach a comprehensive view of kronian auroral processes over the investigated timescale. We identify three source regions for the atmospheric aurorae, including a main oval associated with the bulk of Saturn Kilometric Radiation (SKR), together with polar and equatorward emissions. These observations reveal the coexistence of corotational and subcorototational dynamics of emissions associated with the main auroral oval. Precisely, we show that the atmospheric main oval hosts short-lived subcorotating isolated features together with a bright, longitudinally extended, corotating region locked at the southern SKR phase. We assign the substorm-like event to a regular, internally driven, nightside ion injection possibly triggered by a plasmoid ejection. We also investigate the total auroral energy budget, from the power input to the atmosphere, characterized by precipitating electrons up to 20 keV, to its dissipation through the various radiating processes. Finally, through simulations, we confirm the search-light nature of the SKR rotational modulation and we show that SKR arcs relate to isolated auroral spots. We characterize which radio sources are visible from the spacecraft and we estimate the fraction of visible southern power to a few percent. The resulting findings are discussed in the frame of pending questions as the persistence of a corotating field-aligned current system within a subcorotating magnetospheric cold plasma, the occurrence of plasmoid activity, and the comparison of auroral fluxes radiated at different wavelengths. [less ▲]

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See detailJupiter's aurora in ultraviolet and infrared: simultaneous observations with the Hubble Space Telescope and the NASA Infrared Telescope Facility
Radioti, Aikaterini ULiege; Lystrup, M.; Bonfond, Bertrand ULiege et al

in Journal of Geophysical Research. Space Physics (2013)

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