Home

News / Upcoming Events
Request a Presenter        
List of Presenters        
FAQ        
Contact Information        

Robert West

Scientist
Jet Propulsion Laboratory, California Institute of Technology
4800 Oak Grove Drive
Pasadena, CA 91109

Robert West’s work has been concerned mostly with remote sensing of outer planet atmospheres (including Titan) with emphasis on radiative transfer in scattering atmospheres. His research interests include investigations of the scattering properties of nonspherical and inhomogeneous aerosol particles, microphysical processes for aerosols, cloud structure, and the possible use of aerosol particles and trace chemical species as tracers of atmospheric motion.

Title 1: Giant Planet Atmospheres: Thermal Structure and Aerosols

Abstract 1:

Thermal structure and aerosols are but two facets of atmospheric science open to investigation on the giant planets. Except for the Galileo Probe at Jupiter our only measurements are from remote sensing. This abstract will summarize highlights from recent measurements, long-standing problems, and possible avenues of investigation in the future. Topics to be discussed include the rarity of spectral signatures of condensate clouds, identification of clouds responsible for optical depth variations, chromophore visibility, stratospheric aerosol production, distribution and contribution to radiative energy balance, Jupiter’s UV Great Dark Spot, unique polar vortex signatures on Saturn and Neptune, Saturn’s deep cloud structure, seasonal and nonseasonal variations on Saturn, Uranus at equinox.

Title 2: Haze and Clouds in the Titan Atmosphere

Abstract 2:

This talk will examine observations and models for the Titan haze culminating in recent measurements by the Descent Imager and Spectral Radiometer (DISR) on the Huygens probe and by instruments on the Cassini orbiter. Titan’s organic (‘tholin’) stratospheric haze is optically thick, obscuring the surface at visible wavelengths (but with rapidly diminishing optical depth into the near-infrared). Combined intensity and polarization measurements indicated that it is composed of aggregates of small ‘monomers’. Data from the DISR experiment leads to a picture of an average aggregate particle composed of about 3000 monomers. Data from Cassini orbiter instruments support that view and add important information at other wavelengths and at other locations. The winter polar vortex region is especially interesting. Spectral signatures of condensates are found in that region and no other. The structure in the haze layers is also unique in the winter polar vortex region. Future observations by instruments on Cassini should capture the breakup of the northern polar vortex and the formation of the southern one as the season changes.