Since November of 2006, The Mars Color Imager (MARCI) onboard the Mars Reconnaissance Orbiter (MRO) has obtained multiple-filter daily global images of Mars centered upon a local time (LT) of 3pm. Ultraviolet imaging bands placed within (260 nm) and longward (320 nm) of Hartley band (240-300 nm) ozone (O₃) absorption support retrievals of atmospheric ozone columns, with detection limits (∼ 1 μm-atm) appropriate to mapping elevated O₃ abundances at low latitudes around Mars aphelion, and over mid-to-high latitudes during fall/winter/spring seasons. MARCI O₃ maps for these regions reveal the detailed spatial (∼1° lat/long, for 8x8 pixel binned resolution) and temporal (daily, with substantial LT coverage at pole) behaviors of water vapor saturation conditions that force large variations in water vapor photolysis products (HO_x- OH, HO₂, and H) responsible for the catalytic destruction of O₃ in the Mars atmosphere. A detailed description of the MARCI O₃ data set, including measurement and retrieval characteristics, is provided in conjunction with comparisons to Mars Express SPICAM ozone measurements ( Perrier et al., 2006) and LMD GCM simulated O₃ abundances ( Lefèvre et al., 2004). Presented aspects of the MARCI ozone mapping data set include aphelion increases in low latitude O₃, dynamically evolving high latitude O₃ maxima associated with planetary waves and weather fronts during northern early spring, and distinctive winter/spring O₃ and CO increases within the Hellas basin associated with transport of condensation-enhanced south polar air mass. Comparisons of coincident MARCI measurements and LMD simulations for ice cloud and O₃ columns are considered in the context of potential heterogeneous photochemical processes ( Lefèvre et al., 2008), which are not strongly evidenced in the MARCI observations. Modest interannual variations are exhibited, most notably a 20% reduction in aphelion low latitude O₃ columns following the 2007 perihelic global dust storm.