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S. Pérez-Hoyos, A. Sánchez-Lavega (Universidad del País Vasco), R.G. French (Wellesley College)
Changes in Saturn's reflectivity are well known to happen, mainly because of the noteworthy hemispherical brightness asymmetry but also because its banded structure showed fast changes in contrast between Voyager 1 and 2 flybys. In this work, we analyze the main changes detected with Hubble Space Telescope images from 1994 to 2004 by means of a radiative transfer model that provides useful information about the vertical structure of the upper clouds and hazes (1 mbar to 2 bar). Seasonal, slow brightening (darkening) at short (long) wavelengths of the Southern Hemisphere, in absolute values and with respect to the Northern Hemisphere, is interpreted as a smooth change in the optical depth of the haze at the upper troposphere strongly correlated with seasonal insolation changes. Faster, localized variations in the bands are in general related to the optical properties of the tropospheric particles, most probably altered by dynamical phenomena. Regions of change include the polar latitudes and show an interesting correlation with the zonal wind profile. Acknowledgements: This work was supported by the Spanish MCYT AYA 2003-03216. 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.
The author(s) of this abstract have provided an email address for comments about the abstract: wubpehos@bi.ehu.es
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.