A measurement of the 362 GHz absorption line of Mars atmospheric H sub(2)O sub(2)

The 362.156 GHz absorption spectrum of H sub(2)O sub(2) in the Mars atmosphere was observed on September 4 of 2003, employing the James Clerk Maxwell Telescope (JCMT) sub-millimeter facility on Mauna Kea, Hawaii. Radiative transfer analysis of this line absorption yields an average volume mixing rat...

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Bibliographic Details
Published in:Icarus (New York, N.Y. 1962) N.Y. 1962), 2004-03, Vol.168 (1), p.116-121
Main Authors: Clancy, R T, Sandor, B J, Moriarty-Schieven, G H
Format: Article
Language:English
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Summary:The 362.156 GHz absorption spectrum of H sub(2)O sub(2) in the Mars atmosphere was observed on September 4 of 2003, employing the James Clerk Maxwell Telescope (JCMT) sub-millimeter facility on Mauna Kea, Hawaii. Radiative transfer analysis of this line absorption yields an average volume mixing ratio of 18+/-0.4 ppbv within the lower (0-30 km) Mars atmosphere, in general accordance with standard photochemical models (e.g. Nair et al. 1994, Icarus 111, 124-150). Our derived H sub(2)O sub(2) abundance is roughly three times greater than the upper limit retrieved by Encrenaz et al. (2002, Astron. Astrophys. 396, 1037-1044) from infrared spectroscopy, although part of this discrepancy may result from the different solar longitudes (L sub(s)) of observation. Aphelion-to- perihelion thermal forcing of the global Mars hygropause generates substantial (>200%) increases in HO sub(x) abundances above similar to 10 km altitudes between the L sub(s)=112 degree period of the Encrenaz et al. upper limit measurement and the current L sub(s)=250 degree period of detection (Clancy and Nair, 1996, J. Geophys. Res. 101, 12785-12590). The observed H sub(2)O sub(2) line absorption weakens arguments for non-standard homogeneous (Encrenaz et al. 2002, Astron. Astrophys. 396, 1037-1044) or heterogeneous (Krasnopolsky, 2003a, J. Geophys. Res. 108; 2003b, Icarus 165, 315-325) chemistry, which have been advocated partly on the basis of infrared (8 mu m) non-detections for Mars H sub(2)O sub(2). Observation of Mars H sub(2)O sub(2) also represents the first measurement of a key catalytic specie in a planetary atmosphere other than our own.
ISSN:0019-1035
DOI:10.1016/j.icarus.2003.12.003