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D. A. Glenar, G. Bjoraker, J. C. Pearl (NASA/GSFC), D. L. Blaney (JPL)
We observed Mars at K and L-band wavelengths using the Kitt Peak cryogenic grating spectrometer (CRSP) during the April 1999 opposition (Ls=130). The observations consisted of calibrated drift-scans across the Mars disk, which were reformatted into spectral image cubes spanning 2.18-2.42 microns with spectral resolving power \lambda/\Delta\lambda ~ 2200, and 2.96-4.12 microns with \lambda/\Delta\lambda ~ 800. Telluric absorption features were removed from the data using Vega as the spectral standard, in lieu of solar-type stars. This allowed us to preserve and identify weak solar features in the Mars reflectance spectrum by comparison with ATMOS spectra .
The spatial distribution of south polar CO2 ice was mapped using the measured 2.28 and 2.32 micron "forbidden" spectral features in solid CO2, which have been shown to be sensitive to grain size . The low latitude boundary of the CO2 ice region appears to be diurnally influenced, indicating either a fine-frost component on the surface, or morning CO2 ice clouds. Band depth maps near 3 microns confirm the morphology of a persistent H2O ice cloud band centered near 20 degrees North latitude, which was observed nearly simultaneously by MGS/TES and found to extend over all longitudes .
 Kurucz, R. (1999), private communication.  Calvin, W. M. and T. Z. Martin (1994), J. Geophys. Res., v99, 21143-21152.  Pearl, J. C., M. D. Smith, B. J. Conrath, J. L. Bandfield and P. R. Christensen (1999), B.A.A.S., v31, 1190.
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