The Climate on Venus Fred Taylor Venus Express

The Climate on Venus Fred Taylor Venus Express Interdisciplinary Scientist EGU Vienna 16 April 2008

Venus and Earth • Trace origins & evolution • Understand common processes • Model current climate(s)

Space Atmosphere Radiation Dynamics Chemistry PAST Climate Space Atmosphere FUTURE Surface Interior

Space Atmosphere PAST Climate Future Surface Volcanism Interior ? Interior

Volcanism on Venus - Key Questions • Is volcanic activity present now? • Quantify vocanic input to the atmosphere, past, present & future? • Role in current climate(s)? • Likely past/future evolution?

First observations of SO 2 above Venus’ clouds by means of solar occultation in the infrared D. Belyaev, O. Korablev, A. Fedorova, J. -L. Bertaux, A. -C. Vandaele, R. Drummond, A. Mahieux, V. Wilquet

Sulphur compounds in Earth’s atmosphere (Whitten, Toon, & Turco, 1979)

21 Sept 1991, 100 days after the eruption injected ~20 million tons of SO 2 into stratosphere. Lifetime ~ 100 days

← Venera 9 obtained the first image from the surface of Venus in 1975. ↓ View of a plain in Phoebe Regio from Venera 13 on March 1, 1982

Maat Mons from Magellan Radar Image

Venus has more volcanoes than any other planet in the solar system. Over 1600 major volcanoes or volcanic features are known (see map), and there are many, many more smaller volcanoes. No one has yet counted them all, but the total number may be over 100, 000 or even over 1, 000. [Oregon State University]

The End E. Marcq et al. (VIRTIS) Venus Express extended mission until end of June 2009 Japanese Venus Climate Orbiter arrives December 2010 Total sulphur (as gas) in atmosphere of Venus ≈ 10, 000 times Earth

The Surface of Venus from Orbit by VEx and Magellan J Helbert et al.

Volcanism on Venus - Evidence • Surface panoramas & global radar images – reveal thousands of volcanic features • Sulphur content of atmosphere – Stratospheric SO 2 >> (~105 x) Earth – H 2 SO 4 clouds – Deep atmosphere SO 2 ~ 130 ppm(~105 x) Earth – CO 2 at equilibrium with surface, SO 2 out by > 100 • Earth is volcanic

Volcanism on Venus - Caveats 1. Rainout on Earth removes SO 2 quickly, c. f. 110 Myr for SO 2 removal on Venus 2. If global resurfacing ended 500 Myr ago, atmospheric sulphur may be of ancient origin 3. Could hot dry Venus surface be a source?

Volcanism on Venus - What can VEx do? • • Study SO 2 variability in upper atmosphere Study SO 2 variability in lower atmosphere Find thermal anomalies on the surface New theoretical studies – Models of interior, surface, clouds &c – Earth analogues • Sponsor new missions

Why is it important? • Gases & cloud opacity warm climate • H 2 SO 4 cloud albedo cools climate • Both time-dependent; change if volcanic activity changes or stops • CO 2 and H 2 O are both volcanic gases and may also change Conclusion: processes determine rates, it should be the reverse!

The Surface of Venus seen from Orbit The ‘Greenhouse’ effect on Earth and Venus

Effect of changing composition on the surface temperature of Venus (Bullock 1997) Cloud effect does not include albedo!

Venus Bullock & Grinspoon, JGR, 1996 Surface 400 K

To be continued. . . .