1. Photochemical Distribution of Venusian Sulphur and Halogen Species AND Why Vulcanism cannot be the source for Venusian SO 2 above 80km C. D. Parkinson A.Brecht, S. W. Bougher, F. Mills, M. Allen, X. Zhang and Y. L. Yung DPS 2010 (Poster 10.4)

2. Temperature, H 2 SO 4, and Eddy Mixing Profiles

3. Eddy Mixing Sensitivity Study Case Profiles

4. Std Reference & higher H 2 SO 4 SVP Computations

5. Important reaction pathways related to SO, SO 2, SO 3 and H 2 SO 4

6. Parameter space for possible solutions Blue shaded area shows parameter space where model predicts SO 2 mixing ratios between 0.01 and 1 ppm at 100 km Golden line = max values of SO 2 (67 ppb) from microwave measurements of Sandor et al (2010)

7. Model C Atmosphere: SO x and O x Mixing Ratio

8. Model C Atmosphere: Halogens Mixing Ratio

9. Eddy Mixing Sensitivity Study: SO x

10. Eddy Mixing Sensitivity Study: Halogens

11. Dayside/Nightside Temperature Sensitivity Study: SO x

12. Dayside/Nightside Temperature Sensitivity Study: Halogens

13. SO 2 Boundary Condition Sensitivity Study: SO x No change in SO 2 above 80 km due to pulse in lower atmosphere  Vulcanism not the source of SO 2 above this point

14. SO 2 Boundary Condition Sensitivity Study: Halogens

15. Conclusions SO 2, SO, and halogen species are most sensitive to change in eddy mixing. Least amount of change to SO x and ClO x from temperature changes. Effects on sulphur compounds seems more evident/pronounced for lower boundary value changes in SO 2 mixing ratio below ~80 km, and little effect above ~80 km  vulcanism not the source!!! Effects on ClO x compounds seems more evident/pronounced for lower boundary value changes in SO 2 mixing ratio at the below ~90 km, and little effect above ~90 km, with no change in HCl profile.

16. Preliminary modeling suggests lower HCl abundances result in greater abundances of SO 2, SO, and SO 3 generally lower O 2 abundances, and greater ClO abundances. We will use some of this 1-D chemistry and resulting tracer species profiles in the Venus Thermospheric General Circulation Model (VTGCM) (Bougher et al, 1997) for further comparison to VEx datasets.

17. Std Reference Atmosphere: SO x and O x Number Density

18. Std Reference Atmosphere: Halogens Number Density