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Communication Dans Un Congrès Année : 2010

Exospheric Temperatures at Mars Derived from SPICAM Dayglow Measurements

Résumé

Exospheric temperatures in the atmosphere of Mars can be computed from different dayglow lines and bands measured by SPICAM onboard Mars Express. Depending on the emission, different neutral species can be probed and their variability against solar longitude, solar zenith angles and solar activity be assessed. For the Cameron bands of CO and for CO2+(B-X) at 289.0 nm, the main mechanism is the photo-excitation of CO2 either through dissociation or through ionization. By reconstructing a synthetic spectrum of Mars using an updated variable point spread function and then integrating the intensities for each 37 selected dayglow orbits, the altitude profiles of CO(a3π), CO2+ (B-X) and OI(2972nm) emissions can be retrieved. A clear variation with solar longitude is seen for scale heights and thus exospheric temperatures while geographical coordinates and solar zenith angles variations remain less significant. With the updated analysis scheme, former discrepancies existing between emission exospheric temperatures are reconciled in our new calculations and are compared to previous data (Leblanc et al., 2007). Results for all three lines and their implications on the emission processes and on the neutral atmosphere are reviewed. Also, a new method to adjust the CO2 density with SPICAM observed profiles by a kinetic transport model is presented. Finally, SPICAM retrieved exospheric temperatures are compared and discussed versus recent simulations from the Michigan MTGCM global thermospheric circulation model .
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Dates et versions

hal-04115184 , version 1 (02-06-2023)

Identifiants

Citer

S. W. Bougher, C. Simon, G. Gronoff, O. Witasse, François Leblanc, et al.. Exospheric Temperatures at Mars Derived from SPICAM Dayglow Measurements. American Geophysical Union Fall Meeting 2010, Dec 2010, San Francisco, Unknown Region. pp.abstract id.P52A-07. ⟨hal-04115184⟩
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