Science and Exploration

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

By Keith Cowing

Press Release

astro-ph.EP

October 29, 2022

Filed under astro-ph.EP, Venus

The Impact of Turbulent Vertical Mixing in the Venus Clouds on Chemical Tracers — Vertical profiles of the vertical eddy diffusivity (m2 s ´1 ) in the Venus cloud region calculated with the SO2 tracer for relaxation timescale of 102 s (green), 103 s (blue), 104 s (yellow), 105 s (cyan) and 106 s (red) for the Equator (solid line) and 75˝ (dashed line). The black circles represent the previous estimations (see Table 1) and the black line represents the range of values used for the cloud convective layer in recent chemical models Krasnopolsky (2012); Bierson and Zhang (2020); Rimmer et al. (2021). — Vertical profiles of the vertical eddy diffusivity (m2 s ´1 ) in the Venus cloud region calculated with the SO2 tracer for relaxation timescale of 102 s (green), 103 s (blue), 104 s (yellow), 105 s (cyan) and 106 s (red) for the Equator (solid line) and 75˝ (dashed line). The black circles represent the previous estimations (see Table 1) and the black line represents the range of values used for the cloud convective layer in recent chemical models Krasnopolsky (2012); Bierson and Zhang (2020); Rimmer et al. (2021).

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 SO2 and H2O 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.

Maxence Lefèvre, Emmanuel Marcq, Franck Lefèvre

Comments: 24 pages, 9 figures, 1 table
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2210.09240 [astro-ph.EP] (or arXiv:2210.09240v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2210.09240
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Journal reference: Icarus, 86, 115148, 2022
Related DOI:
https://doi.org/10.1016/j.icarus.2022.115148
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Submission history
From: Maxence Lefèvre
[v1] Mon, 17 Oct 2022 16:33:44 UTC (2,252 KB)
https://arxiv.org/abs/2210.09240

Keith Cowing

SpaceRef co-founder, Explorers Club Fellow, ex-NASA, Away Teams, Journalist, Space & Astrobiology, Lapsed climber.

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