37th DPS Meeting, 4-9 September 2005
Session 20 Outer Planets I
Oral, Tuesday, September 6, 2005, 9:00-10:30am, Law LG19

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[20.05] Vertical Profiles of Phosphine and Ammonia on Saturn Derived from the First Cassini RSS Occultation Observation Using Forward Modeling

P. N. Mohammed, P. G. Steffes (Georgia Institute of Technology), A. J. Kliore, A Anabtawi, S. W. Asmar, E Barbinis, G Goltz, D Johnston (Caltech-JPL), E. A. Marouf (San Jose State University)

The results from the first Cassini Radio Science Subsystem(RSS) occultation, which occurred at the Rev 7 periapse, are being used to derive profiles of the atmospheric constituents encountered by the three frequency (S-, X-, and Ka-band) radio link. A computer model has been developed to simulate ray paths and the ray path parameters in the atmosphere of Saturn encountered during occultation (see Mohammed and Steffes, Bull. Amer. Astron. Soc., 36, no. 4, 1107, 2004). This forward model, which can be used on any oblate planet, will be used to determine the refractive defocusing and derive the profiles of phosphine and ammonia using data observed at Ka-band (32 GHz or 9.3 mm), X-band (8.4 GHz or 3.6 cm) and S-band (2.3 GHz or 13 cm). The results of laboratory measurements of the 9 mm opacity of phosphine and ammonia (Mohammed and Steffes, ICARUS 166, 425-435, 2003) and the centimeter wavelength opacity of these constituents measured under simulated conditions for Saturn (see, e.g., Hoffman et. al. ICARUS 152, 172-184, 2001) were incorporated into the forward radio occultation model used in these derivations.

The author(s) of this abstract have provided an email address for comments about the abstract: gt4863a@prism.gatech.edu

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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.