Measurements and modeling of absorption by CO2 + H2O mixtures in the spectral region beyond the CO2 ν3-band head

Turbet, Martin; Chelin, P.; Landsheere, X.

doi:10.1016/j.icarus.2018.02.009

Cited by 17 publications

(29 citation statements)

References 49 publications

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“…In addition, we incorporated the half-width at half maximum of H 2 O lines broadened by CO 2 (γ H 2 O−CO 2 ) and CO 2 lines broadened by H 2 O (γ CO 2 −H 2 O ), as well as the corresponding temperature dependence exponents ( n H 2 O−CO 2 and n CO 2 −H 2 O ), based on Brown et al (2007); Sung et al (2009); Gamache et al (2016) and Delahaye et al (2016). More details can be found in Turbet et al (2017b) and Tran et al (2018).…”

Section: Radiative Transfermentioning

confidence: 97%

The environmental effects of very large bolide impacts on early Mars explored with a hierarchy of numerical models

Turbet

Gillmann

Forget

et al. 2020

Icarus

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The origin of the presence of geological and mineralogical evidence that liquid water flowed on the surface of early Mars is now a 50-year-old mystery. It has been proposed (Segura et al., 2002(Segura et al., , 2008(Segura et al., , 2012 that bolide impacts could have triggered a long-term climate change, producing precipitation and runoff that may have altered the surface of Mars in a way that could explain (at least part of) this evidence. Here we use a hierarchy of numerical models (a 3-D Global Climate Model, a 1-D radiative-convective model and a 2-D Mantle Dynamics model) to test that hypothesis and more generally explore the environmental effects of very large bolide impacts (D impactor > 100 km, or D crater > 600 km) on the atmosphere, surface and interior of early Mars.Using a combination of 1-D and 3-D climate simulations, we show that the environmental effects of the largest impact events recorded on Mars are characterized by: (i) a short impact-induced warm period (several tens of Earth years for the surface and atmosphere to be back to ambient conditions after very large impact events); (ii) a low amount of hydrological cycling of water (because there is no surface re-evaporation of precipitation). The total cumulated amount of precipitation (rainfall) can be reasonably well approximated by the initial post-impact atmospheric reservoir of water vapour (coming from the impactor, the impacted terrain and from the sublimation of permanent ice reservoirs heated by the hot ejecta layer); (iii) deluge-style precipitation (∼2.6 m Global Equivalent Layer of surface precipitation per Earth year for our reference simulation, quantitatively in agreement with previous 1-D cloud free climate calculations of Segura et al. 2002), and (iv) precipitation patterns that are uncorrelated with the observed regions of valley networks.However, we show that the impact-induced stable runaway greenhouse state predicted by Segura et al. (2012) is physically inconsistent. We nevertheless confirm the results of Segura et al. (2008) and Urata and Toon (2013) that water ice clouds could in theory significantly extend the duration of the post-impact warm period, and even for cloud coverage significantly lower than predicted in Ramirez and Kasting (2017). However, the range of cloud microphysical properties for which this scenario works is very narrow.Using 2-D Mantle Dynamics simulations we find that large bolide impacts can produce a strong thermal anomaly in the mantle of Mars that can survive and propagate for tens of millions of years. This thermal anomaly could raise the near-surface internal heat flux up to several hundreds of mW/m 2 (i.e. up to ∼ 10 times the ambient flux) for several millions years at the edges of the impact crater. However, such internal heat flux is largely insufficient to keep the martian surface above the melting point of water.In addition to the poor temporal correlation between the formation of the largest basins and valley networks (Fassett and Head, 2011), these arguments indicate that the largest ...

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Section: Radiative Transfermentioning

confidence: 97%

The environmental effects of very large bolide impacts on early Mars explored with a hierarchy of numerical models

Turbet

Gillmann

Forget

et al. 2020

Icarus

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“…This was done for consistency with the choice adopted for the widely used MT_CKD self and foreign continua and [2,11]. For CO2 lines, = 5 cm -1 was used in the computation of using Voigt line shapes for consistency with the c-factor corrections proposed in [1,12] (see below). 2-In a second step, the CO2-and H2O-broadened absorptions by the wings of CO2 lines, and , were calculated using the factors of [12] and [1], respectively, and also removed from the experimental transmissions.…”

Section: -mentioning

confidence: 99%

“…For CO2 lines, = 5 cm -1 was used in the computation of using Voigt line shapes for consistency with the c-factor corrections proposed in [1,12] (see below). 2-In a second step, the CO2-and H2O-broadened absorptions by the wings of CO2 lines, and , were calculated using the factors of [12] and [1], respectively, and also removed from the experimental transmissions. The use of these factors, which were obtained in the high frequency wing of the CO2 3 band above 2400 cm -1 to model the sub-Lorentzian behavior of the 2 band lines can introduce uncertainties [since it is known that the factors are different in different spectral regions (e.g.…”

Section: -mentioning

confidence: 99%

“…We here continue the efforts initiated in [1] in order to provide experimental information and models on the continuum absorption by the far line wings of CO2+H2O mixtures. While [1] studied the effect of humidity (of collisions between CO2 and H2O molecules) on the wings of CO2 lines, we focus here on the influence of H2O-CO2 intermolecular interactions on the wings of the water vapor lines, i.e. the so-called CO2broadened H2O continuum.…”

Section: Introductionmentioning

confidence: 96%

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The CO2–broadened H2O continuum in the 100–1500 cm-1 region: Measurements, predictions and empirical model

Turbet

Hanoufa

Landsheere

et al. 2019

Journal of Quantitative Spectroscopy and Radiative Transfer

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Transmission spectra of H2O+CO2 mixtures have been recorded, at 296, 325 and 366 K, for various pressures and mixture compositions using two experimental setups. Their analysis enables to retrieve values of the "continuum" absorption by the CO2-broadened H2O line wings between 100 and 1500 cm -1 . The results are in good agreement with those, around 1300 cm -1 , of the single previous experimental study available. Comparisons are also made with direct predictions based on line-shape correction factors c calculated, almost thirty years ago, using a quasistatic approach and an input H2O-CO2 intermolecular potential. They show that this model quite nicely predicts, with slightly overestimated values, the continuum over a spectral range where it varies by more than three orders of magnitude. An empirical correction is proposed, based on the experimental data, which should be useful for radiative transfer and climate studies in CO2 rich planetary atmospheres.

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“…The errors in computed spectra introduced by assuming purely dry air broadenings and shiftings are thus small (≤2%) and hardly detectable with most Earth observation instruments. However, as shown by laboratory measurements (Baranov, 2011(Baranov, , 2016Baranov et al, 2012;Tran et al, 2018) and by calculations (Hartmann et al, 2018), there are two spectral features, both near 4 μm, where water vapor considerably enhances the absorption: The high frequency wing of the CO 2 ν 3 band and the fundamental collision-induced absorption (CIA) band of N 2 . With respect to dry air, H 2 O can here increase the absorption by more than one order of magnitude (see the supporting information file).…”

Section: Introductionmentioning

confidence: 88%

Indirect Influence of Humidity on Atmospheric Spectra Near 4 μm

Hartmann

Armante

Toon

et al. 2018

Geophysical Research Letters

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We give the first demonstration that humidity has indirect effects on atmospheric spectra near 4 μm, through the influence of collisions with H2O on both the collision‐induced band of N2 and the wings of the CO2 lines. This is shown by comparing computed and measured values of atmospheric transmissions and outgoing radiances. The usual assumption that collisions with H2O and dry air have equal effect on the N2 and CO2 absorptions leads to significantly underestimated absorptions for humid atmospheres. This bias is considerably reduced when the influences of H2O on the N2 and CO2 contributions to the spectra are taken into account using proper spectroscopic models. This opens perspectives of increased accuracy near 4 μm where the atmosphere is relatively transparent, for astronomical observations of outer objects from ground as well as for retrievals of the Earth land/sea surface temperatures from radiances recorded from space.

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Measurements and modeling of absorption by CO2 + H2O mixtures in the spectral region beyond the CO2 ν3-band head

Cited by 17 publications

References 49 publications

The environmental effects of very large bolide impacts on early Mars explored with a hierarchy of numerical models

The environmental effects of very large bolide impacts on early Mars explored with a hierarchy of numerical models

The CO2–broadened H2O continuum in the 100–1500 cm-1 region: Measurements, predictions and empirical model

Indirect Influence of Humidity on Atmospheric Spectra Near 4 μm

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Measurements and modeling of absorption by CO2 + H2O mixtures in the spectral region beyond the CO2 ν3-band head

Cited by 17 publications

References 49 publications

The environmental effects of very large bolide impacts on early Mars explored with a hierarchy of numerical models

The environmental effects of very large bolide impacts on early Mars explored with a hierarchy of numerical models

The CO2–broadened H2O continuum in the 100–1500 cm-1 region: Measurements, predictions and empirical model

Indirect Influence of Humidity on Atmospheric Spectra Near 4 μm

Contact Info

Product

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Measurements and modeling of absorption by CO2 + H2O mixtures in the spectral region beyond the CO2 ν3-band head

The CO2–broadened H2O continuum in the 100–1500 cm-1 region: Measurements, predictions and empirical model