Simultaneous mapping of H₂O and H₂O₂ on Mars from infrared high-resolution imaging spectroscopy

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• 作者：T. Encrenaz ; T.K. Greathouse ; M.J. Richter ; B. Bé ; zard ; T. Fouchet ; F. Lefè ; vre ; F. Montmessin ; F. Forget ; S. Lebonnois ; S.K. Atreya
• 关键词：Mars ; Mars ; atmosphere ; Atmospheres ; composition ; Infrared observations
• 刊名：Icarus
• 出版年：2008
• 出版时间：June 2008
• 年：2008
• 卷：195
• 期：2
• 页码：547-556
• 全文大小：2480 K

文摘

New maps of martian water vapor and hydrogen peroxide have been obtained in November–December 2005, using the Texas Echelon Cross Echelle Spectrograph (TEXES) at the NASA Infra Red Telescope facility (IRTF) at Mauna Kea Observatory. The solar longitude L_s was 332° (end of southern summer). Data have been obtained at 1235–1243 cm⁻¹, with a spectral resolution of 0.016 cm⁻¹ (R=8×10⁴). The mean water vapor mixing ratio in the region [0°–55° S; 345°–45° W], at the evening limb, is abcf13cbe25f942d340e78b6317bdd7"" title=""Click to view the MathML source"" alt=""Click to view the MathML source"">150±50 ppm (corresponding to a column density of 8.3±2.8 pr-μm). The mean water vapor abundance derived from our measurements is in global overall agreement with the TES and Mars Express results, as well as the GCM models, however its spatial distribution looks different from the GCM predictions, with evidence for an enhancement at low latitudes toward the evening side. The inferred mean H₂O₂ abundance is 15±10 ppb, which is significantly lower than the June 2003 result [Encrenaz, T., Bézard, B., Greathouse, T.K., Richter, M.J., Lacy, J.H., Atreya, S.K., Wong, A.S., Lebonnois, S., Lefèvre, F., Forget, F., 2004. Icarus 170, 424–429] and lower than expected from the photochemical models, taking in account the change in season. Its spatial distribution shows some similarities with the map predicted by the GCM but the discrepancy in the H₂O₂ abundance remains to be understood and modeled.