OH Meinel Band Polar Nightglow in the Mars Atmosphere from MRO CRISM Limb Observations

Mars Reconnaisssance Orbiter (MRO) CRISM limb observations over the 2010-2012 period present weak hydroxyl emission in the Meinel bands near 1.4 and 2.9 micron wavelengths. This emission is observed in polar nightglow, over latitudes/seasons/altitudes for which O2 singlet delta polar nightglow (1.27, 1.57 microns) has been detected in CRISM limb nearIR spectra (Clancy et al., JGR, in press 2012). Both polar nightglow phenomena result from poleward transport of odd oxygen/hydrogen into the winter polar, upper atmosphere, whereupon descent to 40-70 km altitudes leads to O2 recombination (O+O+M, producing O2 singlet delta emission) and ozone destruction (O3+H, produciing Meinel band emission). We compare the observed OH band emission rates and structure (1-0, 2-1, 3-2, 2-0) to LMD MGCM simulations of polar night odd oxygen and hydrogen distributions (in time and space, eg Lefèvre et al, Nature, 454, 2008) in the context of band emission models employing "sudden death" versus collisional cascade deactivation (García-Muñoz et al, Icarus, 176, 2005). Existing LMD MGCM comparisons with coincident CRISM polar night O2 singelt delta observations provide direct photochemical constraints to support a uniquely diagnostic view of the quenching mechanisms associated with OH Meinel band emission.