Venus Then and Now: Simulating Sulfuric Acid Clouds Using Latitudinally Dependent VIRA and VeRA Temperature Profiles

Abstract:

Observations from the Pioneer Venus Orbiter (PVO) and from SPICAV/SOIR aboard Venus Express (VEx) have shown the upper haze (UH) of Venus to be highly spatially and temporally variable. Previous models of this system, using typical temperature profiles representative of the Venus atmosphere as a whole, did not investigate the effects of temperature variations on the UH particle distributions. Parkinson et al. (2014, submitted) showed that the inclusion of latitudinally dependent temperature profiles retrieved from SPICAV/SOIR observations in the Venus cloud model of Gao et al. (2014) resulted in markedly different cloud distributions between the different latitude cases, such as a lowered cloud base near the equator and a slightly thicker UH at the poles. Thus, temperature variations across Venus could help explain spatial variations in the atmospheric aerosol distribution. In this work, we expand on the aforementioned study by including VIRA temperature profiles derived from Venera and PVO observations (Kliore et al. 1985) at similar latitudes as the SPICAV/SOIR profiles to assess how the aerosol distribution varies spatially and temporally. By comparing the simulated cloud and haze distributions arising from the two sets of temperature profiles, we can evaluate whether secular changes have occurred in the ~30 years between the PVO and VEx epochs.