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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]

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]

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]

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]

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]