Meridional variations of C2H2 and C2H6 in Jupiter's atmosphere from Cassini CIRS infrared spectra

Nixon, C. A.; Achterberg, R. K.; Conrath, B. J.; Irwin, Patrick; Teanby, N. A.; Fouchet, Thierry; Parrish, P.; Romani, P. N.; Abbas, M. M.; LeClair, A.

doi:10.1016/j.icarus.2006.11.016

Cited by 83 publications

(157 citation statements)

References 70 publications

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“…(Simon-Miller et al, 2006;Nixon et al, 2007Nixon et al, , 2010. We note that Jupiter's subsolar latitude and distance from the Sun changed from 3.3…”

Section: Radiance Differencesmentioning

confidence: 84%

Jupiter’s auroral-related stratospheric heating and chemistry II: Analysis of IRTF-TEXES spectra measured in December 2014

Sinclair

Orton

Greathouse

et al. 2018

Icarus

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We present a retrieval analysis of TEXES (Texas Echelon Cross Echelle Spectrograph (Lacy et al., 2002)) spectra of Jupiter's high latitudes obtained on NASA's Infrared Telescope Facility on December 10-11th 2014. The vertical temperature profile and vertical profiles of C 2 H 2 , C 2 H 4 and C 2 H 6 were retrieved at both high-northern and high-southern latitudes and results were compared in 'quiescent' regions and regions known to be affected by Jupiter's aurora in order to highlight how auroral processes modify the thermal structure and hydrocarbon chemistry of the stratosphere. In qualitative agreement with Sinclair et al. (2017a), we find temperatures in auroral regions to be elevated with respect to quiescent regions at two discrete pressures levels at approximately 1 mbar and 0.01 mbar. For example, in comparing retrieved temperatures at 70• N, 60• W (a representative quiescent region) and 70• N, 180• W (centred on the northern auroral oval), temperatures increase by 19.0 ± 4.2 K at 0.98 mbar, 20.8 ± 3.9 K at 0.01 mbar but only by 8.3 ± 4.9 K at the intermediate level of 0.1 mbar. We conclude that elevated temperatures at 0.01 mbar result from heating by joule resistance of the atmosphere and the energy imparted by electron and ion precipitation. However, temperatures at 1 mbar are considered to result either from heating by shortwave radiation of aurorally-produced haze particulates or precipitation of higher energy population of charged particles. Our former conclusion would be consistent with results of auroral-chemistry models, that predict the highest number densities of aurorally-produced haze particles at this pressure level (Wong et al., 2000(Wong et al., , 2003. C 2 H 2 and C 2 H 4 exhibit enrichments but C 2 H 6 remains constant within uncertainty when comparing retrieved concentrations in the northern auroral region with quiescent longitudes in the same latitude band. At 1 mbar, C 2 H 2 increases from 278.4 ± 40.3 ppbv at 70• N, 60• W to 564.4 ± 72.0 ppbv at 70• N, 180• W and at 0.01 mbar, over the same longitude range at 70• N, C 2 H 4 increases from 0.669 ± 0.129 ppmv to 6.509 ± 0.811 ppmv. However, we note that non-LTE (local thermodynamic equilibrium) emission may affect the cores of the strongest C 2 H 2 and C 2 H 4 lines on the northern auroral region, which may be a possible source of error in our derived concentrations. We retrieved concentrations of C 2 H 6 at 1 mbar of 9.03 ± 0.98 ppmv at 70• N, 60• W and 7.66 ± 0.70 ppmv at 70• N, 180• W. Thus, C 2 H 6 's concentration appears constant (within uncertainty) as a function of longitude at 70• N.

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“…(Simon-Miller et al, 2006;Nixon et al, 2007Nixon et al, , 2010. We note that Jupiter's subsolar latitude and distance from the Sun changed from 3.3…”

Section: Radiance Differencesmentioning

confidence: 84%

Jupiter’s auroral-related stratospheric heating and chemistry II: Analysis of IRTF-TEXES spectra measured in December 2014

Sinclair

Orton

Greathouse

et al. 2018

Icarus

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“…The accuracy and reliability of using NEMESIS for the interpretation of observed spectra from the Cassini mission, both on Saturn and Jupiter, is extremely well documented (e.g., Nixon et al 2007;Fletcher et al 2010). The NEMESIS retrieval algorithm operates by computing a goodness-of-fit metric f, called the cost function, for a forward model.…”

Section: Atmospheric Modelingmentioning

confidence: 99%

D/H Ratios on Saturn and Jupiter from Cassini CIRS

Pierel¹,

Nixon²,

Lellouch³

et al. 2017

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We present new measurements of the deuterium abundance on Jupiter and Saturn, showing evidence that Saturn's atmosphere contains less deuterium than Jupiter's. We analyzed far-infrared spectra from the Cassini Composite Infrared Spectrometer to measure the abundance of HD on both giant planets. Our estimate of the Jovian D/H = (2.95 ± 0.55) × 10 −5 is in agreement with previous measurements by ISO/SWS: (2.25 ± 0.35) × 10 −5 , and the Galileo probe: (2.6 ± 0.7) × 10 −5 . In contrast, our estimate of the Saturn value of (2.10 ± 0.13) × 10 −5 is somewhat lower than on Jupiter (by a factor of 0.71 0.15), contrary to model predictions of a higher ratio: Saturn/ Jupiter = 1.05-1.20. The Saturn D/H value is consistent with estimates for hydrogen in the protosolar nebula (2.1 ± 0.5) × 10 −5 , but its apparent divergence from the Jovian value suggests that our understanding of planetary formation and evolution is incomplete, which is in agreement with previous work.

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“…The NH 3 and PH 3 profiles are also taken from Fletcher et al (2009) and have deep volume mixing ratios of 1.862 × 10 −4 and 1.86 × 10 −6 respectively. The CH 4 profile was obtained from Nixon et al (2007) and has a deep volume mixing ratio of 1.81 × 10 −3 . The CH 3 D profile assumes a constant ratio of CH 3 D/CH 4 of 8 × 10 −5 (Lellouch et al, 2001).…”

Section: Reference Atmospherementioning

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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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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Meridional variations of C2H2 and C2H6 in Jupiter's atmosphere from Cassini CIRS infrared spectra

Cited by 83 publications

References 70 publications

Jupiter’s auroral-related stratospheric heating and chemistry II: Analysis of IRTF-TEXES spectra measured in December 2014

Jupiter’s auroral-related stratospheric heating and chemistry II: Analysis of IRTF-TEXES spectra measured in December 2014

D/H Ratios on Saturn and Jupiter from Cassini CIRS

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

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