DPS 35th Meeting, 1-6 September 2003
Session 40. Outer Planets/Gas Giants IV
Poster, Highlighted on, Friday, September 5, 2003, 3:30-6:00pm, Sierra Ballroom I-II

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[40.01] The Diversity of Cloud Structures in Jupiter's Great Red Spot and Environs: Micro- and Macro- Physical Properties and Dynamical Implications as Derived from HST and Galileo/NIMS Center-to-Limb Spectral Maps

K.H. Baines, T.W. Momary, R.W. Carlson, G.S. Orton (Caltech/JPL)

We utilize high-spatial-resolution spectral maps spanning the uv to near-ir of Jupiter's Great Red Spot (GRS) and surroundings to determine the microphysical properties and vertical structure of the major cloud features in the region. Multi-filter maps obtained both near the central meridian and near the sunlit limb in 29 distinct colors spanning 0.22 to 5.2 microns were obtained contemporaneously on June 26-27 1996 by the Hubble Space Telescope and Galileo/NIMS. These images were used to determine a variety of physical and optical properties for stratospheric and tropospheric aerosol layers including Mie-scattering particle sizes, cloudtop pressure levels, wavelength-dependent opacity, and volume and mass column abundances. Three diverse cloud features were analyzed: (1) the central core of the GRS near 20 degrees planetocentric latitude, (2) the South Tropical Zone (STrZ) to the south of the GRS core, and (3) the fresh spectrally-identifiable ammonia ice cloud (SIAC) imbedded as a plume-like feature within the GRS wake to the northwest of the core center, as identified by Baines et al. (Icarus 159, 74-94, 2002). For the long-lived GRS and STrZ, the sedimentation times of cloud particles were used to constrain the upward flux and vertical speed of ammonia gas required to maintain the cloud features. For the SIAC, particle lifetimes and thus mass fluxes and updraft speeds were estimated from the known windspeed in the region and the dissipation of the cloud downstream from the "head" of the feature representing the updraft region.

Salient results of our preliminary modeling include: Significantly larger particle sizes in the SIAC plume than in the GRS and STrZ ( > 2.2 micron vs. 0.53 and 0.79 micron, respectively, best-fit); a variety of cloudtop altitudes, from 26.1 km above the 1-bar level for the GRS, 20.2 km for the SIAC, and 14.2 for the STrZ; comparable area-integrated cloud mass production rates for the SIAC vs. the 60-times-larger GRS (~100 vs. 50.3 tons/s); and a remarkable updraft speed for the "head" of the SIAC of 1-3 m/s.

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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.