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R.E. Novak (Iona College), M.J. Mumma (Goddard Space Flight Center), M.A. DiSanti, N. Dello Russo (GSFC/Catholic University of America), K. Magee-Sauer (Rowan University)
The singlet Delta state of O2 is produced on Mars by photolysis of ozone by sunlight; detection of the emissions from this state is used as a tracer for atmospheric ozone. The measured ozone is located at altitudes above 20 km since collisional quenching of the singlet Delta state occurs at lower altitudes. We used CSHELL (0.5 arcsec slit width, resolving power ~ 40,000) at IRTF to observe the 1.27 micron band of O2 (singlet Delta - triplet Sigma magnetic dipole transition) near aphelion (Ls=71 deg) on Jan. 21, 1997 (Ls = 67 deg). Post-aphelion observations were made on Mar. 1, 1997 (Ls =84 deg), and Mar. 23, 1999 (Ls =112 deg). The slit was oriented along the north-south direction on Mars and it was stepped east-west to produce spectra separated spatially by ~ 1 arcsec. The spatial resolution along the slit was ~1.0 arcsec (500 km or 10 degrees latitude at the sub-earth point (22.5 degrees N latitude on Mars) for data taken on Mar. 1, 1997 when Mars was 0.70 a.u. from earth). Eight emission lines of O2 were detected in the range between 7898 and 7917 cm-1. Retrieved rotational temperatures between 150 and 200 K indicate a location for the measured ozone between altitudes of 20 and 50 km . Vertical column densities of ozone are found to be greatest near aphelion and are sizable in both the northern and southern hemispheres. For the post-aphelion dates, the column densities are smaller with most of the ozone concentrated in the southern hemisphere. Diurnal variation of the ozone column has also been found. This work is partially funded by NASA/JOVE grant #NAG8-1273 and by a faculty fellowship to RN from Iona College.
The author(s) of this abstract have provided an email address for comments about the abstract: Dr. Robert Novak, Iona College, New Rochelle NY 10801-1890