1. Cassini UVIS solar occultation
01/23/06
D. Shemansky

2. Current observational status
To date Cassini/Huygens probes of the Titan atmosphere do not provide a clear understanding of structure and dynamics.The evidence indicates strong latitudinal and possible longitudinal variation if the experimental results are taken at face value.
INMS results at the top of the atmosphere show a significant variation in density and apparent wave structure.
The in-situ INMS and AACS results disagree by as much as a factor of 4 in gas density estimates in the same spatial volume.

3. Observational status continued
The UVIS stellar occultation results at TB show factors of 2 to 3 larger CH4 density than the INMS probe. It is possible this is caused by latitudinal differences, but measures internal to UVIS suggest the differences may be systematic experimental artifact.
Modeling of the N2 density profile from UVIS data predicts densities at the lower limits of INMS results.

8. T10 UVIS solar occultation

9. Cassini UVIS Titan top of atmosphere solar occultation
Detect atmosphere at 4600 km (h = 2000 km) in 55. – 65. nm photoionization continuum extinction, solar H Lyg line.
Dynamic range ~1000 to obtain density and temperature below 3575 km (h= 1000 km).
N2 and CH4 densities

10. Results on latitudinal structure internal to UVIS
The UVIS TB stellar occultation was located at 40o South.
T10 provides measurements in the vicinity of the south pole.