Remote Sensing of molecular oxygen densities and temperatures in the thermosphere using Stellar Occultation Techniques
Abstract
In this paper we present the results of stellar occultation observations in the thermosphere by the MSX/UVISI instrument. The extinction of stellar spectral signals in the O2 Schumann-Runge continuum (<175 nm) provides a remote sensing tool to measure the O2 number density profile in the thermosphere. The density profile then can be used to infer the thermospheric temperature under diffusive equilibrium assumption. Since the thermosphere has a large temperature gradient, increasing from 200K in the lower thermosphere up to >1000K in the upper thermosphere, accurate knowledge of the Schumann-Runge continuum cross sections as a function of temeperature is required. MSX/UVISI conducted over 50 UV stellar occultation experiments, covering a range of solar activities. In this paper, we use two sets of theoretically calculated cross-sections to retrieve the thermospheric O2 density and temperature profiles. Comparisons with MSIS and NRLMSIS model prediction are made and differences between observations and model predictions are assessed. The accuracy of the temperature dependence of the O2 absorption cross secctions will be evaluated based on the goodness of the fits to the observed occultation transmission spectra.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2004
- Bibcode:
- 2004AGUFMSA23B..05G
- Keywords:
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- 0350 Pressure;
- density;
- and temperature;
- 0355 Thermosphere: composition and chemistry;
- 0394 Instruments and techniques