The NEMESIS planetary atmosphere radiative transfer and retrieval tool

Irwin, Patrick; Teanby, N. A.; Kok, Remco de; Fletcher, Leigh N.; Howett, C. J. A.; Tsang, C. C. C.; Wilson, Colin; Calcutt, S. B.; Nixon, C. A.; Parrish, P.

doi:10.1016/j.jqsrt.2007.11.006

Cited by 502 publications

(505 citation statements)

References 22 publications

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“…8 shows the transmission spectrum produced with the full GP model, now with several model transmission spectra of WASP29b overplotted. These forward models were produced using the NEMESIS retrieval tool (Irwin et al 2008), a radiative transfer code originally developed to investigate the atmospheres of Solar system planets, and recently adapted for exoplanet transmission spectra (Lee, Fletcher & Irwin 2012, Barstow et al, submitted). The grey line shows a model containing a purely H 2 and He atmosphere.…”

Section: Transmission Spectrummentioning

confidence: 99%

A Gemini ground-based transmission spectrum of WASP-29b: a featureless spectrum from 515 to 720 nm

Gibson¹,

Aigrain²,

Barstow³

et al. 2012

Monthly Notices of the Royal Astronomical Society

137

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We report Gemini-South GMOS observations of the exoplanet system WASP-29 during primary transit as a test case for differential spectrophotometry. We use the multi-object spectrograph to observe the target star and a comparison star simultaneously to produce multiple light curves at varying wavelengths. The 'white' light curve and fifteen 'spectral' light curves are analysed to refine the system parameters and produce a transmission spectrum from ∼515 to 720 nm. All light curves exhibit time-correlated noise, which we model using a variety of techniques. These include a simple noise rescaling, a Gaussian process model, and a wavelet based method. These methods all produce consistent results, although with different uncertainties. The precision of the transmission spectrum is improved by subtracting a common signal from all the spectral light curves, reaching a typical precision of ∼1×10 −4 in transit depth. The transmission spectrum is free of spectral features, and given the non-detection of a pressure broadened Na feature, we can rule out the presence of a Na rich atmosphere free of clouds or hazes, although we cannot rule out a narrow Na core. This indicates that Na is not present in the atmosphere, and/or that clouds/hazes play a significant role in the atmosphere and mask the broad wings of the Na feature, although the former is a more likely explanation given WASP-29b's equilibrium temperature of ∼970 K, at which Na can form various compounds. We also briefly discuss the use of Gaussian process and wavelet methods to account for time correlated noise in transit light curves.

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Section: Transmission Spectrummentioning

confidence: 99%

A Gemini ground-based transmission spectrum of WASP-29b: a featureless spectrum from 515 to 720 nm

Gibson¹,

Aigrain²,

Barstow³

et al. 2012

Monthly Notices of the Royal Astronomical Society

137

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“…For the opacity treatment, grey schemes (Rauscher & Menou 2012), binning and averaging of the absorption coefficients (Dobbs-Dixon & Agol 2013) and the correlated-k method (Showman et al 2009) have been used. The correlated-k method has also been used for retrieval analysis and characterisation of hot Jupiter atmospheres (Irwin et al 2008) and to model brown dwarf atmospheres (Burrows et al 1997). Brown dwarfs atmospheres have many similarities with hot Jupiter atmospheres (e.g.…”

Section: Introductionmentioning

confidence: 99%

Accuracy tests of radiation schemes used in hot Jupiter global circulation models

Amundsen

Baraffe

Tremblin

et al. 2014

A&A

166

229

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The treatment of radiation transport in global circulation models (GCMs) is crucial for correctly describing Earth and exoplanet atmospheric dynamics processes. The two-stream approximation and correlated-k method are currently state-of-the-art approximations applied in both Earth and hot Jupiter GCM radiation schemes to facilitate the rapid calculation of fluxes and heating rates. Their accuracy have been tested extensively for Earth-like conditions, but verification of the methods' applicability to hot Jupiter-like conditions is lacking in the literature. We are adapting the UK Met Office GCM, the Unified Model (UM), for the study of hot Jupiters, and present in this work the adaptation of the Edwards-Slingo radiation scheme based on the two-stream approximation and the correlated-k method. We discuss the calculation of absorption coefficients from high-temperature line lists and highlight the large uncertainty in the pressure-broadened line widths. We compare fluxes and heating rates obtained with our adapted scheme to more accurate discrete ordinate (DO) line-by-line (LbL) calculations ignoring scattering effects. We find that, in most cases, errors stay below 10% for both heating rates and fluxes using ∼10 k-coefficients in each band and a diffusivity factor D = 1.66. The two-stream approximation and the correlated-k method both contribute non-negligibly to the total error. We also find that using band-averaged absorption coefficients, which have previously been used in radiative-hydrodynamical simulations of a hot Jupiter, may yield errors of ∼100%, and should thus be used with caution.

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“…The change in brightness temperature due to HCl was calculated using the 222 NEMESIS radiative transfer code (Irwin et al, 2008). This has been used 223 extensively on Jupiter in the past (e.g.…”

mentioning

confidence: 99%

Constraints on Jupiter׳s stratospheric HCl abundance and chlorine cycle from Herschel/HIFI

Teanby

Showman

Fletcher

et al. 2014

Planetary and Space Science

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Detection of HCl on Jupiter would provide insight into the chlorine cycle and external elemental fluxes on giant planets, yet so far has not been possible. Here we present the most sensitive search for Jupiter's stratospheric HCl to date using observations of the 625.907 and 1876.221 GHz spectral lines with Herschel's HIFI instrument. HCl was not detected, but we determined the most stringent upper limits so far, improving on previous studies by two orders of magnitude. If HCl is assumed to be uniformly mixed, with a constant volume mixing ratio above the 1 mbar pressure level and has zero abundance below, we obtain a 3-sigma upper limit of 0.056 ppb; in contrast, if we assume uniform mixing above the 1~mbar level and allow a non-zero but downward-decreasing abundance from 1~mbar to the troposphere based on eddy diffusion, we obtain a 3-sigma upper limit of 0.024 ppb. This is below the abundance expected for a solar composition source, such as comets, and implies that upper atmosphere HCl loss processes are important. We investigated aerosol scavenging using a simple diffusion model and conclude that it could be a very effective mechanism for HCl removal. Transient scavenging by stratospheric NH3 from impacts is another potentially important loss mechanism. This suggests that it is extremely unlikely that HCl is present in sufficient quantities to be detectable in the near future. We summarise the implications for Jupiter's chlorine cycle and conclude that based on a combination of our observations and previous studies of external oxygen supply, a solar composition external source for Jupiter's chlorine combined with stratospheric scavenging by aerosols and NH3 appears the most plausible. 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 AbstractDetection of HCl on Jupiter would provide insight into the chlorine cycle and external elemental fluxes on giant planets, yet so far has not been possible. Here we present the most sensitive search for Jupiter's stratosphericHCl to date using observations of the 625.907 and 1876.221 GHz spectral lines with Herschel's HIFI instrument. HCl was not detected, but we determined the most stringent upper limits so far, improving on previous studies by two orders of magnitude. If HCl is assumed to be uniformly mixed, with a constant volume mixing ratio above the 1 mbar pressure level and has zero abundance below, we obtain a 3-σ upper limit of 0.056 ppb; in contrast, if we assume uniform mixing above the 1 mbar level and allow a non-zero but downward-decreasing abundance from 1 mbar to the troposphere based on eddy diffusion, we obtain a 3-σ upper limit of 0.024 ppb. This is below the abundance expected for a solar composition source, such as comets, and 6 Herschel is an ESA space observatory with science instruments provided by Europeanled Principal Investigator consortia and wit...

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The NEMESIS planetary atmosphere radiative transfer and retrieval tool

Cited by 502 publications

References 22 publications

A Gemini ground-based transmission spectrum of WASP-29b: a featureless spectrum from 515 to 720 nm

A Gemini ground-based transmission spectrum of WASP-29b: a featureless spectrum from 515 to 720 nm

Accuracy tests of radiation schemes used in hot Jupiter global circulation models

Constraints on Jupiter׳s stratospheric HCl abundance and chlorine cycle from Herschel/HIFI

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