Variations of sulphur dioxide at the cloud top of Venus’s dynamic atmosphere



Sulphur dioxide is a million times more abundant in the atmosphere of Venus than that of Earth, possibly as a result of volcanism on Venus within the past billion years1,2. A tenfold decrease in sulphur dioxide column density above Venus’s clouds measured by the Pioneer Venus spacecraft during the 1970s and 1980s has been interpreted as decline following an episode of volcanogenic upwelling from the lower atmosphere3,4. Here we report that the sulphur dioxide column density above Venus’s clouds decreased by an order of magnitude between 2007 and 2012 using ultraviolet spectrometer data from the SPICAV instrument onboard the Venus Express spacecraft. This decline is similar to observations during the 1980s. We also report strong latitudinal and temporal variability in sulphur dioxide column density that is consistent with supply fluctuations from the lower atmosphere. We suggest that episodic sulphur dioxide injections to the cloud tops may be caused either by periods of increased buoyancy of volcanic plumes, or, in the absence of active volcanism, by long-period oscillations of the general atmospheric circulation. The 30-year observational record from Pioneer Venus and Venus Express confirms that episodic injections of sulphur dioxide above the clouds recur on decadal timescales, suggesting a more variable atmosphere than expected.

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Figure 1: Secular evolution of SO2 column density between 2006 and 2012.
Figure 2: Latitudinal profiles of SO2 column density.
Figure 3: More than thirty years of SO2 measurements at Venus’s cloud top.


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The authors wish thank F. W. Taylor and C. Wilson for their valuable comments and insights. Venus Express is a space mission from the European Space Agency (ESA). Denis Belyaev acknowledges support from CNES for a post-doc position at LATMOS. SPICAV-UV data are publicly available at the ESA archive website for data older than 6 months. We wish to acknowledge support from CNES and CNRS.

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E.M. developed the forward model of the venusian upper atmosphere used in this analysis, applied it to the processed observations and wrote the paper. J-L.B. is the Principal Investigator of the SPICAV instrument on-board Venus Express. F.M. maintained the entire workflow and contributed to the scientific discussions. D.B. created and maintained the data pipeline from raw observations to usable radiance factors.

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Correspondence to Emmanuel Marcq or Jean-Loup Bertaux.

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The authors declare no competing financial interests.

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Marcq, E., Bertaux, J., Montmessin, F. et al. Variations of sulphur dioxide at the cloud top of Venus’s dynamic atmosphere. Nature Geosci 6, 25–28 (2013).

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