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D. A. Glenar, W. C. Maguire, M. D. Smith, G. L. Bjoraker, J. C. Pearl (NASA Goddard Space Flight Center), D. L. Blaney (Jet Propulsion Laboratory)
The spectral shapes of the 2 micron, 2\nu1 + \nu3 atmospheric CO2 absorption bands, and nearby contributing hot bands and isotopic bands are all sensitive to temperatures in the lower atmosphere of Mars ( P > ~1 mbar), via the rotational line intensities. This property allows tropospheric temperatures to be probed by ground-based spectral mapping techniques at moderate spectral resolving power. Telescopic measurements over a full hemisphere thus show diurnal temperature changes and atmospheric temperatures near the polar regions, neither of which can be easily measured by Mars orbiting thermal spectrometers.
We describe K-band observations of Mars acquired on July 29 and Sept. 20, 2003 (Ls = 231 and 264), as part of an IRTF/SpeX observing campaign which bracketed the historic 2003 Mars opposition. Long slit grating spectra acquired at moderately high spatial resolution (80 to 130 km, sub-Earth) and spectral resolution (R= 1200 to 1500), were transformed to spatial-spectral (x, y, wavelength) image cubes following the method described by Glenar et al. (Icarus, 2003). Atmospheric temperatures are retrieved from the measurements by fitting to a multi parameter grid of surface-plus-atmosphere spectral reflectance models which incorporate gas parameters, simple representations for surface reflectance shape and dust opacity which is constrained by concurrent TES measurements. The retrievals are consistent with TES temperature measurements and allow extrapolation to polar latitudes as well as a range of local times.
Funding for this work is provided by the NASA Planetary Astronomy Program.
The author(s) of this abstract have provided an email address for comments about the abstract: dave.glenar@gsfc.nasa.gov
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.