Atmospheric Dynamics on Venus: Wind speeds of the lower cloud deck and a sensitivity study of dissipative mechanisms

Tanya Tavenner

In this research I study the atmosphere of Venus. I will derive a data set of the zonal wind speeds and their latitudinal structure in the 48-50km range of the atmosphere, using near-infrared images that highlight cloud motions. The winds will be derived from cloud motions seen in relief from the near-IR thermal emission coming from the hot surface and lower 30km of the atmosphere. I will be tracking individual features in the clouds in order to determine the cloud motion.

My analysis will give both the average motion and the perturbations of individual clouds. These measurements will complement the wind speeds of the upper cloud deck (57-70km), which have previously been derived from UV images of sunlight reflecting off the clouds. Previous observations, such as the measurements taken by the Venera and Pioneer probes, have shown that wind speeds tend to increase with height in the atmosphere of Venus. However, most of these measurements occurred over a time-period of only a few minutes at a single location as the probe entered the atmosphere. My data set will find wind speeds within about 60 degrees of the equators over a range of several days.

These data will provide new constraints on the vertical variability of the atmosphere. Numerical simulations can use these constraints to help us gain a better understanding of the dynamics of Venus' atmosphere. I will be using one such model to probe the sensitivity of the structure of the atmospheric circulation to both radiative and frictional dissipation mechanisms. I will include as constraints for the model, my derived wind speeds and the wind speeds derived from the UV data.