Cloud structure and atmospheric composition of Jupiter retrieved from Galileo near‐infrared mapping spectrometer real‐time spectra

Irwin, Patrick G. J.; Weir, Andrew; Smith, Steve; Taylor, F. W.; Lambert, A.; Calcutt, S. B.; Cameron-Smith, P. J.; Carlson, R. W.; Baines, K. H.; Orton, Glenn S.; Drossart, P.; Encrenaz, Thérèse; Roos-Serote, M.

doi:10.1029/98je00948

Cited by 86 publications

(84 citation statements)

References 47 publications

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“…The best fits therefore suggest a deep volume mixing ratio of 0.76-0.90 ppm. These retrieved global averages are consistent with previous 5-μm studies, including Bjoraker et al (1986) who gives a value of 0.7 ppm from airborne spectroscopic observations, and Irwin et al (1998) who gives a value of 0.77 ppm from Galileo NIMS. However, analyses of Cassini CIRS 7.7-16.6 µm observations have reported higher values: Irwin et al (2004) fit the data using a deep volume mixing ratio that varies between 1.0 and 1.5 ppm, while Fletcher et al (2009) found that values of 1.8-1.9 ppm produced the best fit.…”

Section: Phosphinesupporting

confidence: 77%

“…The presence of several cloud decks made up of particles of different materials and/or sizes can act together to "blur out" the individual spectral features, giving a net effect of a roughly grey cloud. This effect, along with the fact that the study focussed on warmer regions where the clouds are thinner, allowed Irwin et al (1998) to fit the Galileo NIMS 5-μm spectra using a 4-level cloud structure, made up of 0.5 µm tholins, 0.75 µm NH 3 particles, and 0.45 µm and 50 µm NH 4 SH particles.…”

Section: Spectral Featuresmentioning

confidence: 99%

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Cloud structure and composition of Jupiter’s troposphere from 5-μm Cassini VIMS spectroscopy

Giles

Fletcher

Irwin

2015

Icarus

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Jupiter's tropospheric composition and cloud structure are studied using Cassini VIMS 4.5-5.1 µm thermal emission spectra from the 2000-2001 flyby. We make use of both nadir and limb darkening observations on the planet's nightside, and compare these with dayside observations. Although there is significant spatial variability in the 5-μm brightness temperatures, the shape of the spectra remain very similar across the planet, suggesting the presence of a spectrally-flat, spatially inhomogeneous cloud deck. We find that a simple cloud model consisting of a single, compact cloud is able to reproduce both nightside and dayside spectra, subject to the following constraints: (i) the cloud base is located at pressures of 1.2 bar or lower; (ii) the cloud particles are highly scattering; (iii) the cloud is sufficiently spectrally flat. Using this cloud model, we search for global variability in the cloud opacity and the phosphine deep volume mixing ratio. We find that the vast majority of the 5-μm inhomogeneity can be accounted for by variations in the thickness of the cloud decks, with huge differences between the cloudy zones and the relatively cloud-free belts. The relatively low spectral resolution of VIMS limits reliable retrievals of gaseous species, but some evidence is found for an enhancement in the abundance of phosphine at high latitudes.

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Section: Phosphinesupporting

confidence: 77%

Section: Spectral Featuresmentioning

confidence: 99%

Cloud structure and composition of Jupiter’s troposphere from 5-μm Cassini VIMS spectroscopy

Giles

Fletcher

Irwin

2015

Icarus

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“…The radiative transfer, or forward model used in this study is a development of code previously used to analyse Galileo/NIMS observations of Jupiter (Irwin et al, 1998(Irwin et al, , 2001). The code has been converted to run in wavenumber rather than wavelength space and uses the method of correlated-k (Lacis and Oinas, 1991).…”

Section: Forward Modelsmentioning

confidence: 99%

“…of 6~1 O -~ (Kunde et al, 1982), and that at pressures less than 1 bar, the combined effects of vertical eddymixing, photodissociation and equilibration reactions, cause the abundance of phosphine to decrease with height with a fractional scale height (f.s.h.) of approximately 0.3 (Carlson et al, 1993;Irwin et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

Retrievals of jovian tropospheric phosphine from Cassini/CIRS

Irwin

Parrish

Fouchet

et al. 2004

Icarus

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On December 30fh 2000, the Cassini-Huygens spacecraft reached the perijove milestone on its continuing journey to the Saturnian system. During an extended sixmonth encounter, the Composite Mi-ared Spectrometer (CIRS) returned spectra of the Jovian atmosphere, rings and satellites from 10-1400 cm" (1000-7 pm) at a programmable spectral resolution of 0.5 to 15 cm-'. The improved spectral resolution of CIRS over previous IR instrument-missions to Jupiter, the extended spectral range, and lugher signal-to-noise performance provide significant advantages over previous data sets.CIRS global observations of the mid-infrared spectrum of Jupiter at medium resolution (2.5 cm-') have been analysed both with a radiance differencing scheme and an optimal estimation retrieval model to retrieve the spatial variation of phosphine and ammonia fiactional scale height in the troposphere between 60" S and 60" N at a spatial resolution of 6". The ammonia fractional scale height appears to be high over the Equatorial Zone (EZ) but low over the North Equatorial Belt (NEB) and South Equatorial Belt (SEB) indicating rapid uplift or strong vertical miXing in the EZ. The abundance of phosphine shows a similar strong latitudinal variation which generally matches that of the ammonia fractional scale height. However while the ammonia fractional scale height distribution is to a first order symmetric in latitude, the phosphine distribution shows a North/South asymmetry at mid latitudes with higher amounts detected at 40" N than 40" S . In addition the data show that while the ammonia fractional scale height at this spatial resolution appears to be low over the Great Red Spot (GRS), indicating reduced vertical mixing above the -500 mb level, the abundance of phosphine at deeper levels may be enhanced at the northern edge of the GRS indicating upwelling.

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“…The Galileo entry probe's Neutral Mass Spectrometer measured the abundances of H, He, C, N, O, Ne, S, Ar, Kr, and Xe in Jupiter's atmosphere, between the 0.88 and 21.7 bar levels (Niemann et al, 1998;Mahaffy et al, 2000;Wong et al, 2004). The abundance of P was measured remotely from the Galileo orbiter's Near Infrared Mapping Spectrometer (Irwin et al, 1998). In Fig.…”

Section: Planetary Abundances (Nikku Madhusudhan)mentioning

confidence: 99%

Astrobiological Stoichiometry

et al. 2014

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Chemical composition affects virtually all aspects of astrobiology, from stellar astrophysics to molecular biology. We present a synopsis of the research results presented at the ''Stellar Stoichiometry'' Workshop Without Walls hosted at Arizona State University April 11-12, 2013, under the auspices of the NASA Astrobiology Institute. The results focus on the measurement of chemical abundances and the effects of composition on processes from stellar to planetary scales. Of particular interest were the scientific connections between processes in these normally disparate fields. Measuring the abundances of elements in stars and giant and terrestrial planets poses substantial difficulties in technique and interpretation. One of the motivations for this conference was the fact that determinations of the abundance of a given element in a single star by different groups can differ by more than their quoted errors. The problems affecting the reliability of abundance estimations and their inherent limitations are discussed. When these problems are taken into consideration, self-consistent surveys of stellar abundances show that there is still substantial variation (factors of *2) in the ratios of common elements (e.g., C, O, Na, Al, Mg, Si, Ca) important in rock-forming minerals, atmospheres, and biology. We consider how abundance variations arise through injection of supernova nucleosynthesis products into star-forming material and through photoevaporation of protoplanetary disks. The effects of composition on stellar evolution are substantial, and coupled with planetary atmosphere models can result in predicted habitable zone extents that vary by many tens of percent. Variations in the bulk composition of planets can affect rates of radiogenic heating and substantially change the mineralogy of planetary interiors, affecting properties such as convection and energy transport.

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Cloud structure and atmospheric composition of Jupiter retrieved from Galileo near‐infrared mapping spectrometer real‐time spectra

Cited by 86 publications

References 47 publications

Cloud structure and composition of Jupiter’s troposphere from 5-μm Cassini VIMS spectroscopy

Cloud structure and composition of Jupiter’s troposphere from 5-μm Cassini VIMS spectroscopy

Retrievals of jovian tropospheric phosphine from Cassini/CIRS

Astrobiological Stoichiometry

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