DPS 34th Meeting, October 2002
Session 15. Mars
Poster, Chair(s): , Tuesday, October 8, 2002, 3:30-6:00pm, Exhibit Hall

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[15.08] Seasonal and Diurnal Variations of Ozone and Water in the Atmosphere of Mars

R.E. Novak (Iona College), M.J. Mumma (Goddard Space Flight Center), M.A. DiSanti, N. Dello Russo (Catholic University of America, GSFC), K. Magee-Sauer (Rowan University), J. Levkov (Iona College)

Observations of Mars' atmosphere taken at NASA's IRTF on Jan. 8-12, 2002 (Ls ~ 306 degrees) will be compared to previously reported data taken on Jan. 12-14, 2001 (Ls ~ 103 degrees) and Mar. 18-21, 2001 (Ls ~ 133 degrees). Photolysis of ozone in Mars' atmosphere by UV sunlight (Hartley bands) produces a singlet-Delta state of O2; emissions from this state (1.27 micron band) are used as a tracer for atmospheric ozone above ~ 20 km since the singlet-Delta state is quench by carbon dioxide at lower altitudes. Water is detected by observing HDO absorption bands measured near 3.67 microns. We used CSHELL (0.5 arc-sec slit width, resolving power ~ 40,000) on the IRTF for these observations. The slit was oriented north-south on Mars and it was stepped east-west at one arc-sec intervals for the 1.27 and 3.67 micron settings. On Jan. 10, 2002 (and March 21, 2001), the slit was oriented east-west on Mars. No emissions from the singlet Delta state of O2 (1.27 micron setting) were detected for Ls ~ 306 deg; this provides an upper limit for the ozone column density above 20 km and is in direct contrast to observations taken at Ls ~ 103 and Ls ~ 133 when a sizable detection was observed in the southern hemisphere. These data will be presented along with near simultaneous measurements of water column densities retrieved from the HDO bands; maps of water column density for Ls ~ 306 degrees show less atmospheric water than on the 2001 dates. The HDO spectra from these opposite seasons will be used to determine the variation in the D/H ratio between the northern and southern hemispheres of Mars. Spectra taken at 4.67 microns show emissions from CO (2-1 vibrational band) and atmospheric absorptions of isotopic forms of CO and water; these spectra will also be presented. This work was partially funded by grants from NASA (NAG-11398) and NSF (AST-0205397).

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Bulletin of the American Astronomical Society, 34, #3< br> © 2002. The American Astronomical Soceity.