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We report on results of an observing campaign to support the Juno mission. At the beginning of 2016, using TEXES (Texas Echelon cross-dispersed Echelle Spectrograph), mounted on the NASA Infrared Telescope Facility (IRTF), we obtained data cubes of Jupiter in the 1930–1943  cm − 1 spectral ranges (around 5 µm), which probe the atmosphere in the 1–4 bar region, with a spectral resolution of ≈ 0.15  cm − 1 and an angular resolution of ≈ 1.4”. This dataset is analysed by a code that combines a line-by-line radiative transfer model with a non-linear optimal estimation inversion method. The inversion retrieves the vertical abundance profiles of NH 3 — which is the main contributor at these wavelengths — with a maximum sensitivity at ≈ 1–3 bar, as well as the cloud transmittance. This retrieval is performed on more than one thousand pixels of our data cubes, producing maps of the disk, where all the major belts are visible. We present our retrieved NH 3 abundance maps which can be compared with the distribution observed by Juno’s MWR (Bolton et al., 2017; Li et al., 2017) in the 2 bar region and discuss their significance for the understanding of Jupiter’s atmospheric dynamics. We are able to show important latitudinal variations — such as in the North Equatorial Belt (NEB), where the NH 3 abundance is observed to drop down to 60 ppmv at 2 bar — as well as longitudinal variability. In the zones, we find the NH 3 abundance to increase with depth, from 100 ± 15 ppmv at 1 bar to 500 ± 30 ppmv at 3 bar. We also display the cloud transmittance–NH 3 abundance relationship, and find different behaviour for the NEB, the other belts and the zones. Using a simple cloud model (Lacis and Hansen, 1974; Ackerman and Marley, 2001), we are able to fit this relationship, at least in the NEB, including either NH 3 -ice or NH 4 SH particles with sizes between 10 and 100 µm. [ABSTRACT FROM AUTHOR]

We report on spectroscopic observations of Saturn’s stratosphere in July 2011 with the Texas Echelon Cross Echelle Spectrograph (TEXES) mounted on the NASA InfraRed Telescope Facility (IRTF). The observations, targeting several lines of the CH 4 ν 4 band and the H 2 S(1) quadrupolar line, were designed to determine how Saturn’s stratospheric thermal structure was disturbed by the 2010 Great White Spot. A study of Cassini Composite Infrared Spectrometer (CIRS) spectra had already shown the presence of a large stratospheric disturbance centered at a pressure of 2 hPa, nicknamed the beacon B0, and a tail of warm air at lower pressures (Fletcher et al. [2012] Icarus 221, 560–586). Our observations confirm that the beacon B0 vertical structure determined by CIRS, with a maximum temperature of 180 ± 1 K at 2 hPa, is overlain by a temperature decrease up to the 0.2-hPa pressure level. Our retrieved maximum temperature of 180 ± 1 K is colder than that derived by CIRS (200 ± 1 K), a difference that may be quantitatively explained by terrestrial atmospheric smearing. We propose a scenario for the formation of the beacon based on the saturation of gravity waves emitted by the GWS. Our observations also reveal that the tail is a planet-encircling disturbance in Saturn’s upper stratosphere, oscillating between 0.2 and 0.02 hPa, showing a distinct wavenumber-2 pattern. We propose that this pattern in the upper stratosphere is either the signature of thermal tides generated by the presence of the warm beacon in the mid-stratosphere, or the signature of Rossby wave activity. [ABSTRACT FROM AUTHOR]

We present the Infrared spectrometer of SuperCam Instrument Suite that enables the Mars 2020 Perseverance Rover to study remotely the Martian mineralogy within the Jezero crater. The SuperCam IR spectrometer is designed to acquire spectra in the 1.3– 2. 6 μ m domain at a spectral resolution ranging from 5 to 20 nm. The field-of-view of 1.15 mrad, is coaligned with the boresights of the other remote-sensing techniques provided by SuperCam: laser-induced breakdown spectroscopy, remote time-resolved Raman and luminescence spectroscopies, and visible reflectance spectroscopy, and micro-imaging. The IR spectra can be acquired from the robotic-arm workspace to long-distances, in order to explore the mineralogical diversity of the Jezero crater, guide the Perseverance Rover in its sampling task, and to document the samples' environment. We present the design, the performance, the radiometric calibration, and the anticipated operations at the surface of Mars. • We present the SuperCam infrared spectrometer operating on board the Perseverance Rover • It covers the 1.3–2.6 μ m bandpass, at ∼ 10 and 5 nm spectral resolution and sampling • We describe the design, operation, and the data structure of the instrument [ABSTRACT FROM AUTHOR]

We describe the outreach programme of the Europlanet Research Infrastructure (RI), a four-year project funded by the European Union under Framework 7 and designed to maximise planetary science output in Europe. Outreach is a key activity within Europlanet RI and we have put in place a programme to build channels of communication between the planetary science community, the public and the media. One of the major challenges that we have identified is the low value that some parts of the research community place on outreach activities. We describe how we hope to change attitudes and raise the prestige of public engagement in planetary science by establishing an annual prize and a funding scheme. Both schemes are now in their second year, with the third round due to be announced at the EPSC-DPS Joint Meeting in October 2011. [ABSTRACT FROM AUTHOR]

Abstract: We present interferometric mapping of the 225.9-GHz HDO and 203.4-GHz lines on Mars obtained with the IRAM Plateau de Bure facility (PdBI). The observations were performed during martian year 28 (MY28), at L s =320.3° for the HDO line, and at L s =324.3° for the line. The HDO line is detected at the eastern (morning) and western (evening) limbs of the northern hemisphere, corresponding to a water column density in the range 3–6pr.-. The line is not detected, which is compatible with the column densities derived from the HDO line. Quasi-simultaneous far infrared measurements obtained by the Planetary Fourier Spectrometer (PFS) onboard the Mars Express spacecraft confirm our PdBI results, yielding a 5±1pr.- meridionally constant water column abundance. Such a low water abundance during the southern mid-autumn of MY28 does not correspond to the standard martian climatology as observed during the previous years. It was however already retrieved from near-infrared observations performed by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) onboard the Mars Reconnaissance Orbiter spacecraft [Smith, M.D., Wolff, M.J., Clancy, R.T., Murchie, S.L. 2009. CRISM observations of water vapor and carbon monoxide. J. Geophys. Res. 114, doi: 10.1029/2008JE003288]. Our observations thus confirm that the planet-encircling dust storm that occurred during MY28 significantly affected the martian water cycle. Our observations also demonstrate the usefulness of interferometric submillimeter observations to survey the martian water cycle from ground-based facilities. [Copyright &y& Elsevier]

Abstract: Limb and nadir spectra acquired by Cassini/CIRS (Composite InfraRed Spectrometer) are analyzed in order to derive, for the first time, the meridional variations of diacetylene (C4H2) and methylacetylene (CH3C2H) mixing ratios in Saturn’s stratosphere, from 5hPa up to 0.05hPa and 80°S to 45°N. We find that the C4H2 and CH3C2H meridional distributions mimic that of acetylene (C2H2), exhibiting small-scale variations that are not present in photochemical model predictions. The most striking feature of the meridional distribution of both molecules is an asymmetry between mid-southern and mid-northern latitudes. The mid-southern latitudes are found depleted in hydrocarbons relative to their northern counterparts. In contrast, photochemical models predict similar abundances at north and south mid-latitudes. We favor a dynamical explanation for this asymmetry, with upwelling in the south and downwelling in the north, the latter coinciding with the region undergoing ring shadowing. The depletion in hydrocarbons at mid-southern latitudes could also result from chemical reactions with oxygen-bearing molecules. Poleward of 60°S, at 0.1 and 0.05hPa, we find that the CH3C2H and C4H2 abundances increase dramatically. This behavior is in sharp contradiction with photochemical model predictions, which exhibit a strong decrease towards the south pole. Several processes could explain our observations, such as subsidence, a large vertical eddy diffusion coefficient at high altitudes, auroral chemistry that enhances CH3C2H and C4H2 production, or shielding from photolysis by aerosols or molecules produced from auroral chemistry. However, problems remain with all these hypotheses, including the lack of similar behavior at lower altitudes. Our derived mean mixing ratios at 0.5hPa of (2.4±0.3)×10−10 for C4H2 and of (1.1±0.3)×10−9 for CH3C2H are compatible with the analysis of global-average ISO observations performed by Moses et al. (Moses, J.I., Bézard, B., Lellouch, E., Gladstone, G.R., Feuchtgruber, H., Allen, M. [2000a]. Icarus 143, 244–298). Finally, we provide values for the ratios [CH3C2H]/[C2H2] and [C4H2]/[C2H2] that can constrain the coupled chemistry of these hydrocarbons. [Copyright &y& Elsevier]

Abstract: Measuring the spatial distribution of chemical compounds in Saturn’s stratosphere is critical to better understand the planet’s photochemistry and dynamics. Here we present an analysis of infrared spectra in the range 600–1400cm−1 acquired in limb geometry by the Cassini spacecraft between March 2005 and January 2008. We first determine the vertical temperature profiles from 3 to 0.01hPa, at latitudes ranging from 70°N to 80°S. We infer a similar meridional temperature gradient at 1–2hPa as in recent previous studies [Fletcher, L.N., Irwin, P.G.J., Teanby, N.A., Orton, G.S., Parrish, P.D., de Kok, R., Howett, C., Calcutt, S.B., Bowles, N., Taylor, F.W., 2007. Icarus 189, 457–478; Howett, C.J.A., Irwin, P.G.J., Teanby, N.A., Simon-Miller, A., Calcutt, S.B., Fletcher, L.N., de Kok, R., 2007. Icarus 190, 556–572]. We then retrieve the vertical profiles of and from 3 to 0.01hPa and of around 1hPa. At 1hPa, the meridional variation of is found to follow the yearly averaged solar insolation, except for a strong equatorial mole fraction of , nearly two times higher than expected. This enhancement in abundance can be explained by the descent of hydrocarbon-rich air, with a vertical wind speed at the equator of mm/s at 1hPa and mm/s at 0.1hPa. The ethane distribution is relatively uniform at 1hPa, with only a moderate 25% increase from 35°S to 80°S. Propane is found to increase from north to south by a factor of 1.9, suggesting that its lifetime may be shorter than Saturn’s year at 1hPa. At high altitudes (1Pa), and abundances depart significantly from the photochemical model predictions of Moses and Greathouse [Moses, J.I., Greathouse, T.K., 2005. J. Geophys. Res. 110, 9007], except at high southern latitudes (62, 70 and 80°S) and near the equator. The observed abundances are found strongly depleted in the 20–40°S region and enhanced in the 20–30°N region, the latter coinciding with the ring’s shadow. We favor a dynamical explanation for these anomalies. [Copyright &y& Elsevier]

Abstract: We obtained spatially-resolved ultraviolet spectra of Saturn in 1994 with the Faint Object Spectrometer and Goddard High Resolution Spectrograph of the Hubble Space Telescope. We observed four areas on the planet at 15° N, 33° S, 41° S, and 52° S, with a field-of-view of less than 2×2 arcsec2, compared to the 16-arcsec planet diameter. The wavelength range, 1550–2300 Å, encompasses absorption from major hydrocarbons (C2H6, C2H4, C2H2, CH3C2H, C4H2) and water. We find global hydrocarbon abundances and a C2H2 vertical distribution compatible with infrared observations, in contrast with previous analyses of ultraviolet spectra. The stratospheric haze opacity decreases from polar region to the equator. Saturn mid-latitudes are photochemically distinct from the rest of the planet. At 33° S, the spectrum requires either (1) a distinctly different C2H2 vertical distribution or (2) a locally enhanced water abundance. At 41° S, the hydrocarbon abundance exhibits a local minimum, within a global trend of increasing abundance from equator to pole. This global trend may result from an increased abundance of short-lived hydrocarbons such as C4H2. Photochemical models predict a depletion of hydrocarbon molecules in the presence of stratospheric water [Moses et al., 2000. Icarus 143, 166–202]. These results are consistent with a localized influx of water, in the form of high charge to mass ratio particles, flowing into Saturn''s atmosphere at latitudes magnetically linked to the rings. [Copyright &y& Elsevier]

Infrared spectroscopic observations of planets and Saturn's satellite Titan with the Infrared Space Observatory led to many significant discoveries that improved our understanding on the formation, physics and chemistry of these objects. The prime results achieved by ISO are: (1) a new and consistent determination of the D/H ratios on the giant planets and Titan; (2) the first precise measurement of the 15N/14N ratio in Jupiter, a valuable indicator of the protosolar nitrogen isotopic ratio; (3) the first detection of an external oxygen flux for all giant planets and Titan; (4) the first detection of some stratospheric hydrocarbons (CH3, C2H4, CH3C2H, C4H2, C6H6); (5) the first detection of tropospheric water in Saturn; (6) the tentative detection of carbonate minerals on Mars; (7) the first thermal lightcurve of Pluto. [ABSTRACT FROM AUTHOR]

We have used the spectra obtained by the Composite Infrared Spectrometer (CIRS) onboard the Cassini spacecraft to search for latitudinal variation in the 15N/14N ratio on Jupiter. We found no variations statistically significant given the observational and model uncertainties. The absence of latitudinal variations demonstrates that 15NH3 is not fractionated in Jupiter''s atmosphere, and that the measured 15N/14N represents Jupiter''s global value. Our mean value for the global jovian 15N/14N ratio of (2.22±0.52)×10-3 agrees with previous measurements made by Fouchet et al. (2000, Icarus 143, 223–243) and Owen et al. (2001, Astrophys. J. 553, L77–L79). We argue that the jovian isotopic 15N/14N ratio must represent the solar nitrogen isotopic composition. The solar 15N/14N ratio hence significantly differs from the terrestrial value: (15N/14N)⊕=3.68×10-3. This supports the proposition that terrestrial nitrogen originates from a nitrogen reservoir isolated from the main nitrogen reservoir in the proto-solar nebula. The origin and carrier of this isolated reservoir are still unknown. [Copyright &y& Elsevier]

We have determined the following upper limits for the mole fraction of hydrogen halides in Jupiter''s atmosphere from Cassini/CIRS observations: [HF] <2.7×10-11, [HCl] <2.3×10-9, [HBr] <1.0×10-9, [HI] <7.6×10-9. These limits are smaller than solar composition for HF and HCl, and support the halogens'' condensation in ammonium salts predicted by thermochemical models for the upper jovian troposphere. [Copyright &y& Elsevier]

We report on results of an observational campaign to support the Juno mission. At thebeginning of 2016, using TEXES (Texas Echelon cross-dispersed Echelle Spectrograph),mounted on the NASA Infrared Telescope Facility (IRTF), we obtained data cubes ofJupiter in the 1930–1943 cm−1 (5.14 - 5.18 μm) spectral range, which probes theatmosphere in the 1–4 bar region, with a spectral resolution of ≈ 0.15 cm −1 and anangular resolution of ≈ 1.4′′. This dataset is analyzed by a code which combines aline-by-line radiative transfer model with a non-linear optimal estimation inversionmethod. The inversion retrieves the vertical abundance profiles of NH3 — which is themain contributor at these wavelengths — with a maximum sensitivity at ≈ 1–3bar, as well as the cloud transmittance. This retrieval is performed on more thanone thousand pixels of our data cubes, producing maps of the disk, where all themajor belts are visible. We will discuss the results presented in our article, namelyour retrieved NH3 abundance maps which can be compared with the distributionobserved by Juno&#x2019;s MWR (Bolton et al. 2017, Li et al. 2017) in the 2 bar regionand their significance for the understanding of Jupiter&#x2019;s atmospheric dynamics. [ABSTRACT FROM AUTHOR]

Abstract: Limb spectra recorded by the Composite InfraRed Spectrometer (CIRS) on Cassini provide information on abundance vertical profiles of C2H2, C2H4, C2H6, CH3C2H, C3H8, C4H2, C6H6 and HCN, along with the temperature profiles in Titan''s atmosphere. We analyzed two sets of spectra, one at 15° S (Tb flyby) and the other one at 80° N (T3 flyby). The spectral range 600–1400 cm−1, recorded at a resolution of 0.5 cm−1, was used to determine molecular abundances and temperatures in the stratosphere in the altitude range 100–460 km for Tb and 170–495 km for T3. Both temperature profiles show a well defined stratopause, at around 310 km (0.07 mbar) and 183 K at 13° S, and 380 km (0.01 mbar) with 207 K at 80° N. Near the north pole, stratospheric temperatures are colder and mesospheric temperatures are warmer than near the equator. C2H2, C2H6, C3H8 and HCN display vertical mixing ratio profiles that increase with height at 15° S and 80° N, consistent with their formation in the upper atmosphere, diffusion downwards and condensation in the lower stratosphere, as expected from photochemical models. The CH3C2H and C4H2 mixing ratios also increase with height at 15° S. But near the north pole, their profiles present an unexpected minimum around 300 km, observed for the first time thanks to the high vertical resolution of the CIRS limb data. C2H4 is the only molecule having a vertical abundance profile that decreases with height at 15° S. At 80° N, it also displays a minimum of its mixing ratio around the 0.1-mbar level. For C6H6, an upper limit of 1.1 ppb (in the 0.3–10 mbar range) is derived at 15° S, whereas a constant mixing ratio profile of is inferred near the north pole. At 15° S, the vertical profile of HCN exhibits a steeper gradient than other molecules, which suggests that a sink for this molecule exists in the stratosphere, possibly due to haze formation. All molecules display a more or less pronounced enrichment towards the north pole, probably due, in part, to subsidence of air at the north (winter) pole that brings air enriched in photochemical compounds from the upper atmosphere to lower levels. [Copyright &y& Elsevier]

Abstract: We have analyzed data recorded by the Composite Infrared Spectrometer (CIRS) aboard the Cassini spacecraft during the Titan flybys T0–T10 (July 2004–January 2006). The spectra characterize various regions on Titan from 70° S to 70° N with a variety of emission angles. We study the molecular signatures observed in the mid-infrared CIRS detector arrays (FP3 and FP4, covering roughly the 600–1500 cm−1 spectral range with apodized resolutions of 2.54 or 0.53 cm−1). The composite spectrum shows several molecular signatures: hydrocarbons, nitriles and CO2. A firm detection of benzene (C6H6) is provided by CIRS at levels of about around 70° N. We have used temperature profiles retrieved from the inversion of the emission observed in the methane band at 1304 cm−1 and a line-by-line radiative transfer code to infer the abundances of the trace constituents and some of their isotopes in Titan''s stratosphere. No longitudinal variations were found for these gases. Little or no change is observed generally in their abundances from the south to the equator. On the other hand, meridional variations retrieved for these trace constituents from the equator to the North ranged from almost zero (no or very little meridional variations) for C2H2, C2H6, C3H8, C2H4 and CO2 to a significant enhancement at high northern (early winter) latitudes for HCN, HC3N, C4H2, C3H4 and C6H6. For the more important increases in the northern latitudes, the transition occurs roughly between 30 and 50 degrees north latitude, depending on the molecule. Note however that the very high-northern latitude results from tours TB–T10 bear large uncertainties due to few available data and problems with latitude smearing effects. The observed variations are consistent with some, but not all, of the predictions from dynamical-photochemical models. Constraints are set on the vertical distribution of C2H2, found to be compatible with 2-D equatorial predictions by global circulation models. The D/H ratio in the methane on Titan has been determined from the CH3D band at 1156 cm−1 and found to be . Implications of this deuterium enrichment, with respect to the protosolar abundance on the origin of Titan, are discussed. We compare our results with values retrieved by Voyager IRIS observations taken in 1980, as well as with more recent (1997) disk-averaged Infrared Space Observatory (ISO) results and with the latest Cassini–Huygens inferences from other instruments in an attempt to better comprehend the physical phenomena on Titan. [Copyright &y& Elsevier]

Global mineralogical mapping of Mars by the Observatoire pour la Mineralogie, l'Eau, les Glaces et l'Activité (OMEGA) instrument on the European Space Agency's Mars Express spacecraft provides new information on Mars' geological and climatic history. Phyllosilicates formed by aqueous alteration very early in the planet's history (the "phyllocian" era) are found in the oldest terrains; sulfates were formed in a second era (the "theiikian" era) in an acidic environment. Beginning about 3.5 billion years ago, the last era (the "siderikian") is dominated by the formation of anhydrous ferric oxides in a slow superficial weathering, without liquid water playing a major role across the planet. [ABSTRACT FROM AUTHOR]

Jupiter's upper troposphere and stratosphere are host to a rich dynamical and chemical activity. This modulates the thermal structure and distribution of trace species and aerosols, which, in turn, impact the atmospheric radiative budget and dynamics. In this paper, we present a computationally efficient 1-D seasonal radiative model, with convective adjustment, of Jupiter's atmosphere. Our model takes into account radiative forcings from the main hydrocarbons (methane, ethane, acetylene), ammonia, collision-induced absorption, several cloud and haze layers and an internal heat flux. We parametrize four tropospheric cloud and haze layers. Three of them (one tropospheric cloud near 800 mbar, one upper tropospheric haze, one stratospheric haze) are set to be uniform with latitude. On the contrary, we prescribe the spatial distribution of another UV-absorbing "polar" stratospheric haze comprising fractal aggregates based on published observational constraints, as their concentration varies significantly with latitude. We detail sensitivity studies of the equilibrium temperature profile to several parameters (hydrocarbon abundances, cloud particle sizes and optical depths, optical properties of the stratospheric polar haze, etc.). We then discuss the expected seasonal, vertical and meridional temperature variations in Jupiter's atmosphere and compare the modeled thermal structure to that derived from Cassini and ground-based thermal infrared observations. We find that the equilibrium temperature in the 5–30 mbar pressure range is very sensitive to the chosen stratospheric haze optical properties, sizes and number of monomers. One of the three sets of optical properties tested yields equilibrium temperatures that match well, to first order, the observed ones. In this scenario, the polar haze significantly warms the lower stratosphere (10–30 mbar) by up to 20 K at latitudes 45–60°, and reproduces an observed north–south asymmetry in stratospheric temperature. The polar haze also acts to shorten significantly the radiative timescales, estimated by our model to 100 (Earth) days at the 10-mbar level. At pressures lower than 3 mbar, our modeled temperatures systematically underestimate the observed ones by ∼ 5 K. This might suggest that other processes, such as dynamical heating by wave breaking or by eddies, or a coupling with thermospheric circulation, play an important role. An alternate possibility is that the uncertainty on the abundance of hydrocarbons is responsible for this mismatch. In the troposphere, we can only match the observed lack of meridional gradient of temperature by varying the internal heat flux with latitude. We then exploit knowledge of heating and cooling rates (using our radiative seasonal model combined to observational constraints on the temperature) to diagnose the residual-mean circulation in Jupiter's stratosphere. This is done under the assumption that the eddy heat flux convergence term is negligible. In the Earth's stratosphere, the residual-mean circulation obtained with this method represents well, on a seasonal scale, the transport of tracers in regions where wave breaking and dissipation are weak. However, on Jupiter, in the lower stratosphere (5–30 mbar), the residual-mean circulation strongly depends on the assumed properties of the stratospheric haze. Our main conclusion is that it is crucial to improve our knowledge on the different radiative forcing terms (in particular regarding the stratospheric haze properties) to increase our confidence in the estimated circulation. By extension, this will also be crucial for future 3D GCM studies. • A seasonal radiative-convective model of Jupiter's atmosphere is presented. • Stratospheric polar haze greatly impact the equilibrium temperatures. • We evaluate the residual-mean stratospheric circulations and discuss caveats. [ABSTRACT FROM AUTHOR]

The Cassini mission unveiled the intense and diverse activity in Saturn's atmosphere: banded jets, waves, vortices, equatorial oscillations. To set the path towards a better understanding of those phenomena, we performed high-resolution multi-annual numerical simulations of Saturn's atmospheric dynamics. We built a new Global Climate Model [GCM] for Saturn, named the Saturn DYNAMICO GCM, by combining a radiative-seasonal model tailored for Saturn to a hydrodynamical solver based on an icosahedral grid suitable for massively-parallel architectures. The impact of numerical dissipation, and the conservation of angular momentum, are examined in the model before a reference simulation employing the Saturn DYNAMICO GCM with a 1/2° latitude-longitude resolution is considered for analysis. Mid-latitude banded jets showing similarity with observations are reproduced by our model. Those jets are accelerated and maintained by eddy momentum transfers to the mean flow, with the magnitude of momentum fluxes compliant with the observed values. The eddy activity is not regularly distributed with time, but appears as bursts; both barotropic and baroclinic instabilities could play a role in the eddy activity. The steady-state latitude of occurrence of jets is controlled by poleward migration during the spin-up of our model. At the equator, a weakly-superrotating tropospheric jet and vertically-stacked alternating stratospheric jets are obtained in our GCM simulations. The model produces Yanai (Rossby-gravity), Rossby and Kelvin waves at the equator, as well as extratropical Rossby waves, and large-scale vortices in polar regions. Challenges remain to reproduce Saturn's powerful superrotating jet and hexagon-shaped circumpolar jet in the troposphere, and downward-propagating equatorial oscillation in the stratosphere. • A new Global Climate Model for Saturn with radiative transfer • High-resolution numerical simulations on a duration of 15 Saturn years • Results on zonal jets, waves, eddies in Saturn's troposphere [ABSTRACT FROM AUTHOR]

The ExoMars Trace Gas Orbiter (TGO), a mission by ESA and Roscosmos, was launched inMarch 2016 and reached its final, near-circular 400 km orbit around Mars in March, 2018. Onboard TGO, the Atmospheric Chemistry Suite (ACS) is a set of three spectrometers includinga thermal-infrared channel, TIRVIM. This Fourier-transform spectrometer covers the range600–6000 cm−1 (1.7–17μm) with a spectral resolution of 1.2 cm−1. We focus here on nadirobservations in the range 600-1300 cm−1, which covers absorption by CO2 (centered at 667cm−1), water ice clouds (centered at 820 cm−1) and dust (centered at 1100 cm−1).The advantage of the TIRVIM data set over previous instruments comes from theTGO orbit, which is not sun-synchronous and was designed to sample a completedaily cycle every 55 days. Hence, TIRVIM has the capacity to uniquely study boththe diurnal and seasonal variability of the thermal structure, dust and ice cloudopacity. We have developed a radiative transfer model coupled to a retrieval algorithm thatexploits TIRVIM spectra to simultaneously retrieve vertical profiles of the temperature from 5 to 45 km, surface temperature, and integrated optical depth of dust and water ice clouds.This algorithm was tested and validated against synthetic observations generated undervarious conditions (local time, seasons, latitude, aerosol load,...). We have thenapplied this algorithm to the first 45 days of TIRVIM data acquired in March-April,2018. The retrieved temperature profiles have been validated against thousandsof co-located measurements acquired by the Mars Climate Sounder around 3amand 3pm, a limb-viewing radiometer onboard Mars Reconnaissance Orbiter. Theagreement between the two data sets is very satisfactory. In particular, the amplitudeof the diurnal thermal tide as seen by MCS is very well captured by TIRVIM atpressures greater than 10 Pa. However, TIRVIM underestimates it in the range 1–10 Pa,which is due to a much poorer vertical resolution in this region (as expected froma nadir-viewing sounder). We will present these results with an emphasis on thediurnal cycle of the atmospheric temperature and the aerosols load, along withcomparisons with predictions from the LMD Mars GCM. Analysis of TIRVIM dataacquired during the dust storm in June-July 2018 is in progress and will also bepresented. Acknowledgements: The ACS experiment is led by IKI in Moscow. We acknowledgesupport by CNES and Roscosmos. [ABSTRACT FROM AUTHOR]

Since January 2012, we have been monitoring the behavior of sulfur dioxide and water on Venus, using the TEXES (Texas Echelon Cross-Echelle Spectrograph) imaging spectrometer at the NASA InfraRed Telescope Facility (IRTF, Mauna Kea Observatory). We present here the observations obtained in January 2016, December 2016, January 2017, July 2017, July 2018 and September 2018. As in the case of our previous observations (Encrenaz et al. 2012, 2013, 2016), data have been recorded in two spectral ranges around 1345 cm-1 (7.4 μm) and 530 cm-1 (18.9 μm). At 7 μm, SO2, CO2 and HDO (used as a proxy for H2O) are observed, and the cloudtop of Venus is probed at an altitude of about 64 km. We concentrate here on the 7.4 μm data. The volume mixing ratio of SO2 is estimated using the SO2/CO2 line depth ratios of weak transitions; the H2O volume mixing ratio is derived from the HDO/CO2 line depth ratio, assuming a D/H ratio of 200 times the Vienna Standard Mean Ocean Water (SMOW) value. As reported in our previous analyses, the SO2 mixing ratio shows strong variations with time and also over the disk, which is an indication of the formation of SO2 plumes with a lifetime of a few hours. In contrast, the H2O abundance is remarkably uniform over the disk and shows moderate variations as a function of time. We have performed a statistical analysis of the behavior of the SO2 plumes, using all TEXES data between 2012 and 2017. They appear to be located largely around the equator. Their distribution as a function of local time seems to show a depletion around noon. The distribution of SO2 plumes as a function of longitude shows no clear pattern, apart from a possible depletion around 100E-150E and around 300E-360E. We see no clear correlation or anti-correlation between the SO2 and H2O abundances at the cloudtop, neither in the individual maps nor over the long term. Finally, there is a good agreement between the TEXES results and those obtained in the UV range (SPICAV/Venus Express and UVI/Akatsuki), which shows that SO2 observations obtained in the thermal infrared can be used to extend the local time coverage of the SO2 measurements obtained in the UV range. [ABSTRACT FROM AUTHOR]

We have carried out ground-based seasonal monitoring of hydrogen peroxide on Mars since 2003. This presentation is on the latest set of observations using thermal imaging spectroscopy, with two observations of the planet near opposition, in May 2016 (Ls = 148.5°, diameter = 17") and July 2018 (Ls = 209°, diameter = 23"). Data have been recorded in the 1232 - 1242 cm-1 range (8.1 micron) with the Texas Echelon Cross Echelle Spectrograph (TEXES) mounted at the 3-m Infrared Telescope Facility (IRTF) at Maunakea Observatory in Hawaii. As in the case of our previous analyses, maps of H2O2 have been obtained using line depth ratios of weak transitions of H2O2 divided by a weak CO2 line. The H2O2 map of April 2016 shows a strong dichotomy between the Northern and Southern hemispheres, as predicted by the photochemical model developed in the Mars Climate Database (Forget et al. 1999) and in the Global Environmental Multiscale model (Daerden et al. 2019). The second measurement in July 2018 was taken in the middle of the MY 34 global dust storm. H2O2 was not detected, with a disk-integrated 2-sigma upper limit of 10 ppbv, while both the MCD and the LEM models predicted a value above 20 ppbv that was actually observed by TEXES in 2003 in the absence of dust storm (Encrenaz et al., 2004). This July 2018 depletion is probably the result of the high dust content in the atmosphere at the time of our observations, which led to a decrease of the water vapor column density in the relevant altitude range, as observed by PFS on Mars Express during this period (Giuranna and Wolkenberg, 2019). GCM simulations using the GEM model show that the H2O depletion leads to a drop of H2O2 due to the depletion of HO2 radicals whose self-recombination gives rise to H2O2. Our data provide new constraints to the photochemical modelling of H2O2 in the presence of a high dust content. In parallel, we have reprocessed the whole TEXES dataset of H2O2 measurements using the latest version of the GEISA database (2015). We have recently found that there is a significant difference in the H2O2 line strengths between the 2003 and 2015 versions of GEISA. Therefore, all H2O2 mixing ratios up to 2014 from TEXES measurements have been reduced by a factor of about 1.75. As a consequence, in four cases (Ls around 80°, 100°, 150° and 209°), H2O2 abundances show contradictory values between different Martian years, while, at Ls = 209°, the cause seems to be the increased dust content associated with the global dust storm. The inter-annual variability in the three other cases remains unexplained at this time. [ABSTRACT FROM AUTHOR]