High-Resolution Microwave Images of Saturn
A. W. GROSSMAN 1,
D. O. MUHLEMAN 1, and
G. L. BERGE 1
1 Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125.
An analysis of high-resolution microwave images of Saturn and Saturn's individual rings is presented. Radio interferometric observations of Saturn taken at the Very Large Array in New Mexico at wavelengths of 2 and 6 centimeters reveal interesting new features in both the atmosphere and rings. The resulting maps show an increase in brightness temperature of about 3 K from equator to pole at both wavelengths, while the 6-centimeter map shows a bright band at northern mid-latitudes. The data are consistent with a radiative transfer model of the atmosphere that constrains the well-mixed, fully saturated, NH3 mixing ratio to be 1.2 x 10-4 in a region just below the NH3 clouds, while the observed bright band indicates a 25 percent relative decrease of NH3 in northern mid-latitudes. Brightness temperatures for the classical rings are presented. Ring brightness shows a variation with azimuth and is linearly polarized at an average value of about 5 percent. The variations in ring polarization suggest that at least 20 percent of the ring brightness is the result of a single scattering process.
Submitted on May 24, 1989
Accepted on July 25, 1989
