Determination of the Venus eddy diffusion profile from CO and CO2 profiles using SOIR/Venus Express observations

Mahieux, A.; Yelle, R. V.; Yoshida, Nao; Robert, Séverine; Piccialli, Arianna; Nakagawa, Hiromu; Kasaba, Yasumasa; Mills, F. P.; Vandaele, Ann Carine

doi:10.1016/j.icarus.2021.114388

Cited by 13 publications

(21 citation statements)

References 37 publications

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“…The detailed examination of the eddy diffusion coefficient between the mesosphere to the thermosphere (cf. Mahieux et al., 2021) will be conducted with CO and CO 2 number densities and temperature profiles retrieved from SO channel of NOMAD using ASIMUT. An accurate eddy diffusion coefficient will be much more useful for the parameterization of a 1D photochemical model and GCM model.…”

Section: Discussionmentioning

confidence: 99%

Variations in Vertical CO/CO₂ Profiles in the Martian Mesosphere and Lower Thermosphere Measured by the ExoMars TGO/NOMAD: Implications of Variations in Eddy Diffusion Coefficient

Yoshida

Nakagawa

Aoki

et al. 2022

Geophysical Research Letters

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CO is produced by the photodissociation of CO 2 and recycled to CO 2 by the catalytic cycle involving HOx in the Martian atmosphere (e.g., McElroy & Donahue, 1972). The photochemical lifetime of CO is ∼6 years in the lower atmosphere (Krasnopolsky, 2007). The previous nadir observations revealed latitudinal and seasonal distributions of CO in the lower atmosphere, which indicate CO 2 condensation/sublimation in the polar caps and dynamics (Encrenaz et al., 2006;Smith et al., 2009Smith et al., , 2021. In the middle and upper atmosphere (>∼50 km), the photochemical lifetime of CO becomes much longer due to the decrease in HOx species density. Thus, the characteristic times of production and eddy diffusion of CO are shorter than the photochemical lifetime of CO in

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Section: Discussionmentioning

confidence: 99%

Variations in Vertical CO/CO₂ Profiles in the Martian Mesosphere and Lower Thermosphere Measured by the ExoMars TGO/NOMAD: Implications of Variations in Eddy Diffusion Coefficient

Yoshida

Nakagawa

Aoki

et al. 2022

Geophysical Research Letters

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“…The estimation of the vertical eddy diffusion for heat, using potential temperature instead of tracer abundance in Equation 2, gives a value between 10 3 and 10 4 m 2 s ´1 for the Equator in the deep cloud convective region and around 10 4 m 2 s ´1 for the cloud-top convective layer, and between 10 4 and 10 5 m 2 s ´1 for high latitudes. Above the clouds and below the Rayleigh damping layer, K zz is estimated from 1 to 10 m 2 s ´1, at least one order of magnitude lower than the values estimated from 80 km (Mahieux et al, 2021). The small-scale turbulence only plays a minor role in the mixing in this region.…”

Section: Previous Estimationsmentioning

confidence: 62%

“…McGouldrick and Toon (2007) estimated K zz between 1 and 10 3 m 2 s ´1 in the 50-57 km range. Above the clouds, K zz was estimated using the SOIR/Venus Express CO 2 and CO profiles at around 360 m 2 s ´1 from 80 km (Mahieux et al, 2021).…”

Section: Vertical Eddy Diffusionmentioning

confidence: 99%

“…HST Imaging Spectrograph was used to observe Venus (Jessup et al, 2015(Jessup et al, , 2020 at cloud-top altitudes, albedo darkening was measured and explained by a possible increase of the convective vertical mixing and the injection of the unknown absorbing species. Using the SOIR/Venus Express CO 2 and CO profiles above the clouds and 1D photochemical model, Mahieux et al (2021) estimated the vertical mixing from 80 to 140 km.…”

Section: Introductionmentioning

confidence: 99%

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The Impact of Turbulent Vertical Mixing in the Venus Clouds on Chemical Tracers

Lefèvre,

Marcq,

Lefèvre

2022

Preprint

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Venus' clouds host a convective layer between roughly 50 and 60 km that mixes heat, momentum, and chemical species. Observations and numerical modelling have helped to understand the complexity of this region. However, the impact on chemistry is still not known. Here, we use for the first time a three-dimensional convection-resolving model with passive tracers to mimic SO 2 and H 2 O for two latitudinal cases. The tracers are relaxed towards a vertical profile in agreement with measured values, with a timescale varying over several orders of magnitude. The vertical mixing is quantified, it is strong for a relaxation timescale high in front of the convective timescale, around 4 hours. The spatial and temporal variability of the tracer due to the convective activity is estimated, with horizontal structures of several kilometres. At the Equator, the model is resolving a convective layer at the cloud top (70 km) suggested by some observations, the impact of such turbulent activity on chemical species is accounted for the first time. From the resolved convective plumes, a vertical eddy diffusion is estimated, consistent with past estimations from in-situ measurements, but several orders of magnitude higher than values used in 1D chemistry modelling. The results are compared to observations, with some spatial and temporal variability correlation, suggesting an impact of the convective layer on the chemical species.

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“…Next, we explore the system response to varying eddy diffusivities. The diffusivity in the middle and upper atmosphere is constrained by observations (Lane & Opstbaum 1983;Mahieux et al 2021;Woo & Ishimaru 1981), but it is largely unknown in the lower atmosphere. Krasnopolsky & Pollack (1994) inferred smaller diffusivity below the clouds.…”

Section: Exploration Of a Large Parameter Spacementioning

confidence: 99%

A Fast, Semi-analytical Model for the Venusian Binary Cloud System

Dai,

Zhang,

Cui

2022

Preprint

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The Venusian clouds originate from the binary condensation of H 2 SO 4 and H 2 O. The two components strongly interact with each other via chemistry and cloud formation. Previous works adopted sophisticated microphysical approaches to understand the clouds. Here we show that the observed vapor and cloud distributions on Venus can be well explained by a semi-analytical model. Our model assumes local thermodynamical equilibrium for water vapor but not for sulfuric acid vapor, and includes the feedback of cloud condensation and acidity to vapor distributions. The model predicts strong supersaturation of the H 2 SO 4 vapor above 60 km, consistent with our recent cloud condensation model. The semi-analytical model is 100 times faster than the condensation model and 1000 times faster than the microphysical models. This allows us to quickly explore a large parameter space of the sulfuric acid gas-cloud system. We found that the cloud mass loading in the upper clouds has an opposite response of that in the lower clouds to the vapor mixing ratios in the lower atmosphere. The transport of water vapor influences the cloud acidity in all cloud layers while the transport of sulfuric acid vapor only dominates in the lower clouds. This cloud model is fast enough to be coupled with the climate models and chemistry models to understand the cloudy atmospheres of Venus and Venus-like extra-solar planets.

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Determination of the Venus eddy diffusion profile from CO and CO2 profiles using SOIR/Venus Express observations

Cited by 13 publications

References 37 publications

Variations in Vertical CO/CO₂ Profiles in the Martian Mesosphere and Lower Thermosphere Measured by the ExoMars TGO/NOMAD: Implications of Variations in Eddy Diffusion Coefficient

Variations in Vertical CO/CO₂ Profiles in the Martian Mesosphere and Lower Thermosphere Measured by the ExoMars TGO/NOMAD: Implications of Variations in Eddy Diffusion Coefficient

The Impact of Turbulent Vertical Mixing in the Venus Clouds on Chemical Tracers

A Fast, Semi-analytical Model for the Venusian Binary Cloud System

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Determination of the Venus eddy diffusion profile from CO and CO2 profiles using SOIR/Venus Express observations

Cited by 13 publications

References 37 publications

Variations in Vertical CO/CO2 Profiles in the Martian Mesosphere and Lower Thermosphere Measured by the ExoMars TGO/NOMAD: Implications of Variations in Eddy Diffusion Coefficient

Variations in Vertical CO/CO2 Profiles in the Martian Mesosphere and Lower Thermosphere Measured by the ExoMars TGO/NOMAD: Implications of Variations in Eddy Diffusion Coefficient

The Impact of Turbulent Vertical Mixing in the Venus Clouds on Chemical Tracers

A Fast, Semi-analytical Model for the Venusian Binary Cloud System

Contact Info

Product

Resources

About

Variations in Vertical CO/CO₂ Profiles in the Martian Mesosphere and Lower Thermosphere Measured by the ExoMars TGO/NOMAD: Implications of Variations in Eddy Diffusion Coefficient

Variations in Vertical CO/CO₂ Profiles in the Martian Mesosphere and Lower Thermosphere Measured by the ExoMars TGO/NOMAD: Implications of Variations in Eddy Diffusion Coefficient