Photochemical Distribution of Venusian Sulphur and Halogen SpeciesAND

Why Vulcanism cannot be the source for Venusian SO2 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)

Temperature, H2SO4, and Eddy Mixing Profiles

Eddy Mixing Sensitivity Study Case Profiles

Std Reference & higher H2SO4 SVP Computations

Important reaction pathways related to SO, SO2, SO3 and H2SO4

Parameter space for possible solutions

Blue shaded area shows parameter space where model predicts SO2

mixing ratios between 0.01 and 1 ppm at 100 km

Golden line = max values of SO2 (67 ppb) from microwave measurements of Sandor et al (2010)

Model C Atmosphere: SOx and Ox Mixing Ratio

Model C Atmosphere: Halogens Mixing Ratio

Eddy Mixing Sensitivity Study: SOx

Eddy Mixing Sensitivity Study: Halogens

Dayside/Nightside Temperature Sensitivity Study: SOx

Dayside/Nightside Temperature Sensitivity Study: Halogens

SO2 Boundary Condition Sensitivity Study: SOx

No change in SO2 above 80 km due to pulse in lower

atmosphere Vulcanism not the source of SO2 above this point

SO2 Boundary Condition Sensitivity Study: Halogens

Conclusions

• SO2, SO, and halogen species are most sensitive to change in eddy mixing.

• Least amount of change to SOx and ClOx from temperature changes.

• Effects on sulphur compounds seems more evident/pronounced for lower boundary value changes in SO2 mixing ratio below ~80 km, and little effect above ~80 km vulcanism not the source!!!

• Effects on ClOx compounds seems more evident/pronounced for lower boundary value changes in SO2 mixing ratio at the below ~90 km, and little effect above ~90 km, with no change in HCl profile.

• Preliminary modeling suggests lower HCl abundances result in greater abundances of SO2, SO, and SO3 generally lower O2 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.

Std Reference Atmosphere: SOx and Ox Number Density

Std Reference Atmosphere: Halogens Number Density