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[51.25] Observations of High Altitude CO₂ Hot Bands in Mars Global Surveyor TES Limb Tangent Spectral Averages

W.C. Maguire, J.C. Pearl, M.D. Smith (NASA/GSFC), B.J. Conrath (Cornell), A.A. Kutepov (Munich), M.S. Kaelberer, E. Winter (Raytheon ITSS), P.R. Christensen (Arizona State)

The MGS/TES instrument has now been in orbit for about 1.5 Martian years. Using respectively 6.45 and 12.5 cm^-1 resolution observations from late Martian winter (L_s = 323^\circ) to minimize the water vapor content, we have produced long-tangent-path limb spectral averages for one of six available detectors over successive 5 km vertical extents, beginning at 15-20 km. All of these averages show the strong 15\mum CO₂ fundamental. At lower altitudes, as expected the broad 850-1300 cm^-1 dust contribution to the limb radiance obscures other features in this extended spectral region. This is consistent with models of vertical dust profiles which, however, show a rapid decrease in dust concentration above 3-4 scale heights (~ 40 km). Features at both 10.4 and 9.5\mum are readily observed in the 35-40 km average. The former feature we identify as a CO₂ hot band while the latter is comprised partly of another CO₂ hot band. The ~ 100 cm^-1 wide feature at 9.5\mum is visible in both low and intermediate resolution averages. Since this feature first becomes readily apparent in the 35-40 km average and is narrower than the broad dust contribution, we conclude it's not integral with the broad dust feature. On the other hand, the 9.5\mum feature is wider than can be accounted for by modeling the adjacent CO₂ 9.4\mum hot band. We will discuss the 9.5\mum feature in more detail.

This work was supported in part by NASA's Mars Data Analysis Program.