Seasonal variations of photochemical tracers at low and middle latitudes on Mars: Observations and models |
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Authors: | Vladimir A Krasnopolsky |
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Institution: | Department of Physics, Catholic University of America, Washington, DC 20064, USA |
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Abstract: | Mars Express observations give ozone abundances that are smaller than those from the ground-based infrared heterodyne and HST observations at low and middle latitudes. Both ground-based and Mars Express observations of the O2 dayglow at 1.27 μm, which originates from photolysis of ozone, are in mutual agreement after correction for the local time variability. Therefore a problem appears: whether the MEX ozone data are compatible with (1) the observed O2 dayglow intensities and (2) the photochemical model by Krasnopolsky Krasnopolsky, V.A., 2006. Icarus 185, 153-170] within uncertainties of its reaction rate coefficients. That model involves heterogeneous loss of H2O2 on water ice and agrees with the observations of the O2 dayglow, H2O2, and the ground-based and HST ozone. The answers are ‘yes’ to both questions. A version of the model is given that fits the MEX ozone as well as the observed O2 dayglow and H2O2. Laboratory studies of two reaction rate coefficients could indicate a preferable version of the model and a preferable set of the ozone data (MEX versus the ground-based and HST). The predicted seasonal behavior of H2O2 is different from that in the model by Lefevre et al. Lefevre, F., Bertaux, J.L., Clancy, R.T., Encrenaz, T., Fast, K., Forget, F., Lebonnois, S., Montmessin, F., Perrier, S., 2008. Nature 454, 971-975], and future observations may help to choose between the models. |
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Keywords: | Mars Mars atmosphere Photochemistry Atmospheres chemistry Atmospheres composition |
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