This project centers on the development and application of a new, automated algorithm to measure the speeds of winds in Saturn's observable weather layer. The PI and a graduate student will improve on their technique of Advected Corrected Correlation Image Velocimetry (ACCIV); this algorithm automatically tracks the movement of cloud features between pairs of in-situ images obtained from spacecraft, and extracts velocity fields with much higher efficiency and resolution than existing automated or manual methods. They will apply this analysis to Cassini images of Saturn, particularly in the region of the polar vortices, and extract velocities with uncertainties of only 1 meter per second. They will produce a public, user friendly version of ACCIV and make it available to the planetary science and broader research communities.
NASA satellite images of planets such as Saturn are colorful, often breath-taking views of our solar system. However, to make those images useful to scientists and provide quantitative information about the winds of the atmosphere requires a more detailed analysis. Most of the analyses to date have been based on the idea that, to a first approximation, the planet’s clouds move passively with the winds. By tracking the clouds through a series of spacecraft images, primitive velocity maps were made of Saturn’s atmosphere. However, the velocity fields, in general, have uncertainties that are too large to allow us to view the details of the polar vortices and other features of the atmosphere. In this study, we developed a new, automated method for extracting very precise velocity fields from the cloud patterns. In this method individual clouds are not tracked, rather the global pattern as a whole is tracked and a velocity field is determined that is a best fit for how the entire atmospheric pattern moves. We have shown quantitatively how this produces velocities with smaller errors. We also have shown that features, such as swirling vortices, that were not visible with other velocity extraction techniques, can be teased out of the images.
