[Previous] | [Session 18] | [Next]
S. Pérez-Hoyos, A. Sánchez-Lavega, J.F. Rojas (Universidad del País Vasco (Spain)), J.R. Acarreta (Laboratorio de Astrofísica y Física Fundamental- INTA (Spain)), R.G. French (Wellesley College (USA))
We present a photometric study of Saturn's Southern Hemisphere based on the Hubble Space Telescope yearly campaigns in the 1990's. Calibrated images taken with the WFPC2 in a wide spectral coverage (218nm-1042nm) were used in order to constrain the properties and the temporal changes of the atmospheric particles and the optical depths of clouds and hazes in the stratosphere and upper troposphere of the planet. A radiative transfer code that employs the ``doubling-adding" technique has been used to model the observed center to limb variation in absolute reflectivity along fixed latitudes. The standard atmospheric model includes the scattering and gas absorption, two or three layers of particles forming a thin stratospheric haze, and a tropospheric haze and cloud, both probably composed of ammonia ice. The free parameters of the model are the single scattering albedo and phase function of the particles, as well as the optical depth and height of the clouds. We have selected three regions to be studied in the Southern Hemisphere: the equator, the mid-latitudes and the South Polar Region. The final aim of this project is to determine the latitudinal, short-termed and seasonal variations in the cloud structure of Saturn before the arrival of the Cassini-Huygens mission. Acknowledgements: This work was supported by the Spanish MCYT Plan Nacional de Astronomía y Astrofísica 2000-0932. SPH acknowledges a PhD fellowship from the Spanish MECD. RGF was supported in part by NASA's Planetary Geology and Geophysics Program NAG5-10197 and STSCI Grant GO-08660.01A.
If the author provided an email address or URL for general inquiries,
it is as follows:
Bulletin of the American Astronomical Society, 34, #3< br> © 2002. The American Astronomical Soceity.