* 07/16/96 Constraints on Titan’s Hign Haze from Cassini UVIS/ISS and Huygens DISR Observations *

Pioneer and Voyager Measurements * 07/16/96 Pioneer and Voyager Measurements West and Smith Icarus 90 (1991) *

Fractal Aggregates High-dimension Cluster-cluster Low-dimension * 07/16/96 Fractal Aggregates Cluster-cluster aggregate High-dimension aggregate Low-dimension aggregate M. Lemmon Dissertation *

Cassini/Huygens Observations * 07/16/96 Cassini/Huygens Observations UVIS Stellar Occultations: Aerosol extinction vertical profiles 170-190 nm UVIS Spectral Image Cubes: Scattering properties (phase function, albedo) 170-190 nm) ISS Limb Images: Scattering Profiles above 300 Km, 270 nm to 934 nm ISS Disk images: Aerosol Albedo, Surface Albedo (near 940 nm), Spatially-Resolved Polarization, Methane-Band Imagery DISR internal radiation measurements. Particle phase function, optical depth, wavelength dependence from ~400 nm to 1600 nm, but only at one location and altitudes less than 150 Km *

* 07/16/96 Titan EUVFUV *

* 07/16/96 938 nm Phase Angle 10 24 60 137 147 Data Model Ratio *

* 07/16/96 Phase 10 137 60 147 *

Derived Haze Properties * 07/16/96 Derived Haze Properties H = 65 Km Surface average albedo = 0.35; Haze single-scatter albedo = 0.99 *

Near-term plan Modeling * 07/16/96 Near-term plan Modeling Currently testing a spherical-shell intensity code (JPL) against pseudo spherical-shell code (Y. Yung and D. Tice, Caltech). Outcome will determine if a polarization pseudo-spherical code can be used. Need a model to relate a physical particle (e.g. aggregates) to optical properties (Mackowski and Mishchenko multi-sphere code combined with aggregate model) Run a suite of models for various size parameters, refractive indices and vertical profiles and compare with data (ISS, UVIS and DISR). Multi-components and/or vertical structure will be required – investigate direct inversion techniques Add NIMS data (1-5 micron wavelength) *