Muro, G.D., Sayanagi, K. M., Ewald, S. P., Ingersoll, A. P. (2010). "Clouds, Bands and Discrete Features on Saturn: Comparisons between Cassini and Voyager" American Astronomical Society, DPS meeting #42, #11.18.


Abstract
We examine new images returned from Cassini spacecraft's ISS camera to analyze tropospheric cloud morphology of Saturn. We compare our findings to Voyager 2 observations to search for changes in global cloud morphology. Images were acquired around the equinox and our datasets provide near-global coverage in multiple wavelength bands. We find that the clouds exhibit the highest contrasts in infrared continuum centered at 752 & 939 nm (CB2 & CB3 filters, respectively) and 727 & 890 nm methane bands (MT2 & MT3).
We compare the present day location of Saturn's bands to those of the Voyager era. We reconfirm multiple features that were previously found in Voyager's visible and Cassini infrared images in the northern hemisphere. First, we examine the Ribbon wave found by the Voyager missions (Sromovsky et al. 1983; Godfrey and Moore, 1986) at multiple wavelength bands. Next, we examine the behavior of a dark vortex that exhibits many similarities to the vortex labeled by Sromovsky et al. as Brown Spot 1. Our data also shows a visible-light counterpart to the String of Pearls feature, which appeared as a series of planet encircling bright spots in 5-micron VIMS images (Momary et al. 2006), suggesting that they are cloud clearings. Our images confirm that there are indeed a string of dark cloud-free spots in the region, which enable us to study their dynamics and compare our results to the VIMS measurements by Choi et al (2009). We also compare the appearance of the north-polar hexagon at multiple wavelengths. Our data also provides good coverage in the southern hemisphere, and we compare our results to Voyager images in 1980-81 and images acquired during the early phase of Cassini mission.
Supported by the Cassini Project and a Summer Undergraduate Research Fellowship from Caltech.