Volume 648, April 2021
|Number of page(s)||4|
|Section||Letters to the Editor|
|Published online||26 April 2021|
Letter to the Editor
Evidence for SO2 latitudinal variations below the clouds of Venus
LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, France
2 LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, 5 place Jules Janssen, 92195 Meudon, France
Accepted: 14 April 2021
Context. Sulphur dioxide (SO2) is highly variable above the clouds of Venus, yet no spatial or temporal variability below the clouds had been known until now.
Aims. In order to constrain Venus’s atmospheric circulation and chemistry (including possible volcanic outgassing), more accurate SO2 measurements below the clouds are therefore needed.
Methods. We used the high-resolution iSHELL spectrometer located at the NASA IRTF to record thermal night-side spectra, which we fitted using an updated forward radiative transfer model that was previously employed to process SpeX/IRTF and VIRTIS-H/Venus Express spectra.
Results. We report, for the first time, an increase in SO2 with increasing latitude (+30% between the minimum near 15°S and > 35°N). This is consistent with the interaction between the Hadley-cell circulation and a postulated vertical profile in SO2 estimated to increase between 30 and 40 km in altitude, as previously suggested by in situ ISAV measurements.
Conclusions. This SO2 variability challenges our current understanding of Venus’s tropospheric thermochemistry and underlines the high scientific return from high-resolution spectroscopy from, for example, future orbiters.
Key words: planets and satellites: atmospheres / techniques: spectroscopic
© E. Marcq et al. 2021
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