Distribution of H2O and SO2 in the atmosphere of Venus

The large variability of H2O and SO2in the atmosphere of Venus above the cloud tops is puzzling, especially since there is little evidence for their variability in the lower atmosphere. We note three important related facts: (1) The abundances of H2O and SO2in the deep atmosphere are of the same order of magnitude ~100 ppmv, (2) there is a rapid decrease in H2O and SO2 just above the cloud tops, resulting in sharp vertical gradients in their vertical profiles, and (3) the primary removal mechanism for H2O and SO2above the cloud tops is formation of H2SO4 aerosols. In this work we examine the possibility that H2O and SO2could mutually regulate each other in 1-D and 2-D models.