Characterization of a Thick Ozone Layer in Mars' Past

摘要: All three terrestrial planets with atmospheres support O3 layers of some thickness. While currently only that Earth is substantial enough to be climatically significant, we hypothesize ancient Mars may also have supported a thick layer during volcanically quiescent periods whenthe atmosphere was oxidizing. To characterize such an and determine the significance its fedback on Martian climate, apply 1D line-by-line radiative-convective model under clear sky conditions coupled simple photochemical model. The parameter space atmospheric pressure, insolation, O2 mixing fraction are explored find favorable formation. We most likely for surface pressures 0.3-1.0 bar, could produce column comparable modern fractions approaching 1%. However, even thinner layers, significant UV shielding occurs along feedback both energy budget photochemistry atmosphere. In particular, CO2 condensation in middle inhibited characteristics H2O dissociation modified, shifting from direct photolysis dominated state similar more Earth-like controlled by O(1D) attack.