The impact of turbulent vertical mixing in Venus’ clouds on chemical tracers

Vertical profiles of the vertical turbulent diffusivity (m2 s ´1 ) in the cloudy region of Venus calculated with the SO2 tracer for a relaxation time scale of 102 s (green), 103 s (blue), 104 s (yellow), 105 s (cyan) and 106 s (red) for the equator (solid line) and 75˝ (dotted line). The black circles represent previous estimates (see Table 1) and the black line represents the range of values ​​used for the convective cloud layer in recent chemical models from Krasnopolsky (2012); Bierson and Zhang (2020); Rimmer et al. (2021). — Vertical profiles of the vertical turbulent diffusivity (m2 s ´1 ) in the Venus cloud region calculated with the SO2 tracer for a relaxation time scale of 102 s (green), 103 s (blue), 104 s (yellow ), 105 s (cyan) and 106 s (red) for the equator (solid line) and 75˝ (dotted line). The black circles represent previous estimates (see Table 1) and the black line represents the range of values ​​used for the convective cloud layer in recent chemical models from Krasnopolsky (2012); Bierson and Zhang (2020); Rimmer et al. (2021).

Venus’ clouds host a convective layer between about 50 and 60 km that mixes heat, momentum and chemical species. Observations and numerical modeling have made it possible to understand the complexity of this region. However, the impact on the chemistry is not yet known.

Here, we use for the first time a three-dimensional model of convective resolution with passive tracers to mimic SO2 and H2O for two latitudinal cases. The tracers are relaxed to a vertical profile in agreement with the measured values, with a time scale varying over several orders of magnitude. The vertical mixing is quantified, it is strong for a relaxation time scale high in front of the convective time scale, around 4 hours.

The spatial and temporal variability of the tracer due to convective activity is estimated, with horizontal structures of several kilometers. At the equator, the model resolves a convective cloud top layer (70 km) suggested by some observations, the impact of such turbulent activity on chemical species is taken into account for the first time.

From the resolved convective plumes, vertical turbulent diffusion is estimated, consistent with past estimates from in situ measurements, but several orders of magnitude higher than values ​​used in 1D chemical modelling. The results are compared to observations, with some correlation of spatial and temporal variability, suggesting an impact of the convective layer on chemical species.

Maxence Lefèvre, Emmanuel Marcq, Franck Lefèvre

Comments: 24 pages, 9 figures, 1 table
Subjects: Terrestrial and planetary astrophysics (astro-ph.EP)
Cite as: arXiv:2210.09240 [astro-ph.EP] (or arXiv:2210.09240v1 [astro-ph.EP] for this release)
https://doi.org/10.48550/arXiv.2210.09240
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Revised reference: Icare, 86, 115148, 2022
Related DOI:
https://doi.org/10.1016/j.icarus.2022.115148
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Submission history
By: Maxence Lefevre
[v1] Mon Oct 17 2022 4:33:44 PM UTC (2252 KB)
https://arxiv.org/abs/2210.09240