Composition of Titan's upper atmosphere from Cassini UVIS EUV stellar occultations
Abstract
Identifying seasonal and spatial variability in Titan's atmospheric structure is a key factor in improving theoretical models of atmospheric loss and understanding the physical processes that control the loss rate. In this work, the extreme ultraviolet (EUV) stellar occultation lightcurves from the Cassini Ultraviolet Imaging Spectrograph (UVIS) experiment are analyzed. N_2 and CH_4 atmospheric profiles between 1000 and 1400 km are determined by using an optimized grid search retrieval method to provide a complete χ^2 surface for the two species abundance parameters at each level in the atmosphere. Kinetic temperature is extracted from hydrostatic analysis of the N_2 profiles, and indicates a high level of variability related to energy deposition in the upper atmosphere. These results are compared to in situ measurements by the Ion Neutral Mass Spectrometer (INMS), which also probes this region of Titan's atmosphere.
Additional Information
© 2013 Elsevier Ltd. Received 1 December 2012; Received in revised form 10 July 2013; Accepted 5 August 2013; Available online 16 August 2013. This research was supported in part by the Cassini UVIS program via NASA Grant JPL.1459109 to the California Institute of Technology. YLY and XZ were supported in part by NASA Grant NNX09AB72G to the California Institute of Technology. DES was supported through Space Environment Technologies. JAK would like to thank Michael Line for many productive discussions concerning data analysis and retrieval methodology, as well as Joseph Westlake for assistance in providing INMS derived nitrogen and methane atmospheric profiles.Additional details
- Eprint ID
- 43869
- Resolver ID
- CaltechAUTHORS:20140219-095532767
- JPL.1459109
- NASA
- NNX09AB72G
- NASA
- Space Environment Technologies
- Created
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2014-02-20Created from EPrint's datestamp field
- Updated
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2021-11-10Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences