Mapping of Ozone and Water in the Atmosphere of Mars near the 1997 Aphelion |
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| Authors: | Robert E NovakMichael J Mumma Michael A DiSanti Neil Dello Russo Karen Magee-Sauer |
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| Institution: | a Department of Physics, Iona College, New Rochelle, New York, 10801-1890, f1rnovak@iona.eduf1b Laboratory for Extraterrestrial Physics, NASA Goddard Space Flight Center, Code 690, Greenbelt, Maryland, 20771-0003c Department of Physics, Catholic University of American, Washington, DC, 20064-0001d Laboratory for Extraterrestrial Physics, NASA Goddard Space Flight Center, Code 690.2, Greenbelt, Maryland, 20771-0003e Department of Physics and Chemistry, Rowan University, Glassboro, New Jersey, 08028-1702 |
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| Abstract: | We present absolute abundances and latitudinal variations of ozone and water in the atmosphere of Mars during its late northern spring (Ls=67.3°) shortly before aphelion. Long-slit maps of the a1Δg state of molecular oxygen (O2) and HDO, an isotopic form of water, were acquired on UT January 21.6 1997 using a high-resolution infrared spectrometer (CSHELL) at the NASA Infrared Telescope Facility. O2(a1Δg) is produced by ozone photolysis, and the ensuing dayglow emission at 1.27 μm is used as a tracer for ozone. Retrieved vertical column densities for ozone above ∼20 km ranged between 1.5 and 2.8 μm-atm at mid- to low latitudes (30°S-60°N) and decreased outside that region. A significant decrease in ozone density is seen near 30°N (close to the subsolar latitude of 23.5°N). The rotational temperatures retrieved from O2(a-X) emissions show a mean of 172±2.5 K, confirming that the sensed ozone lies in the middle atmosphere (∼24 km). The ν1 fundamental band of HDO near 3.67 μm was used as a proxy for H2O. The retrieved vertical column abundance of water varies from 3 precipitable microns (pr-μm) at ∼30°S to 24 pr-μm at ∼60°N. We compare these results with current photochemical models and with measurements obtained by other methods. |
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| Keywords: | Mars atmosphere |
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