Long-term variations in the microwave brightness temperature of the Uranus atmosphere

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2006.04.012 Byline: M.J. Klein, M.D. Hofstadter Keywords: Uranus; Uranus; atmosphere; Atmospheres; dynamics; Radio observations Abstract: We present a self-consistent, 36-year record of the disk-averaged radio brightness of Uranus at wavelengths near 3.5 cm. It covers nearly half a uranian year, and includes both equatorial and polar viewing geometries (corresponding to equinox and solstice, respectively). We find large (greater than 30 K) changes over this time span. In agreement with analyses made of more limited microwave data sets, our observations suggest the changes are not caused by geometric effects alone, and that temporal variations may exist in the deep uranian troposphere down to pressures of tens of bars. Our data also support an earlier suggestion that a rapid, planetary-scale change may have occurred in late 1993 and early 1994. The seasonal record presented here will be useful for constraining dynamical models of the deep atmosphere, and for interpreting observations made during Uranus' 2007 equinox passage. As part of a multi-wavelength observing campaign for this event, the Goldstone-Apple Valley Radio Telescope (GAVRT) project will continue to make frequent, single-dish observations near 3.5 cm. Author Affiliation: Jet Propulsion Laboratory, Mail Stop 303-401, 4800 Oak Grove Drive, Pasadena, CA 91109, USA Article History: Received 26 August 2005; Revised 10 April 2006