DPS 2001 meeting, November 2001
Session 19. Mars Atmosphere Posters
Displayed, 9:00am Tuesday - 3:00pm Saturday, Highlighted, Wednesday, November 28, 2001, 10:30am-12:30pm, French Market Exhibit Hall

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[19.13] Mars Aphelion Clouds During the 1999 Opposition - IR Spectral Mapping Results

D. A. Glenar, G. Bjoraker, J. C. Pearl (NASA/GSFC), D. L. Blaney (JPL)

We present high spectral resolution (R=800-2300) near-infrared mapping observations at Ls=130, acquired by drift scanning a long-slit spectrometer across the Mars disk. Data were reformatted into calibrated spectral image cubes (x,y,wavelength) spanning 2.19 to 4.12 microns, which distinguish atmospheric CO2 features, solar features and surface and aerosol spectra.

Maps of relative band depth between 3.0 and 3.8 microns trace H2O clouds, and show the diurnal evolution of features in the persistent Northern summer aphelion cloud belt, which was mapped at fixed local time by MGS/TES. Cloud optical depths and the particle size distribution were estimated using a two-stream, single layer scattering model, with Mie coefficients derived from recently published H2O ice optical constants [1]. A comparison of data and model generated spectra show morning to afternoon growth of the prominent cloud feature West of Elysium Mons, and some evidence for a bi-modal particle size distribution. Thinner clouds not associated with topographical features show little or no diurnal change.

[1] Clapp, M. L., R. E. Miller and D. R. Worsnop (1995), J. Phys. Chem., v99, 6317.

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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