Vertical Structure of Jupiter's Atmosphere at the Galileo Probe Entry Latitude

Abstract

The vertical structure of Jupiter's atmosphere is examined to better characterize the latitudinal region of the Galileo probe entry site: +5°–10° planetographic latitude. One-hundred Hubble Space Telescope images of Jupiter taken with the 893- and 953-nm filters on 13 and 17 February 1995, 5 October 1995, and 14 May 1996 are analyzed, and a two-cloud model of the jovian atmosphere (D. M. Kuehn and R. F. Beebe 1993,Icarus101,282–292) is used to interpret center-to-limb variations of bright plume heads and adjacent dark areas in the latitude region +2°–10°. For both the plume heads and dark areas, the top of the ammonia cloud deck reaches a pressure level of roughly 200 mbar, and the cloud has an optical depth of between 6 and 7. The optical depth of the stratospheric haze layer is 0.59 for the plumes and 0.34 for the dark regions, while the single scattering albedo of the ammonia cloud deck is 0.996 for the plumes and 0.950 for the dark regions. Sensitivity tests motivated by the preliminary results from the Galileo probe net flux radiometer and nephelometer experiments indicate that the ammonia cloud deck may have a patchy structure.