Vertical profiles of Mars 1.27 μm O2 dayglow from MRO CRISM limb Spectra: Seasonal/global behaviors, comparisons to LMDGCM simulations, and a global definition for Mars water vapor profiles

Abstract : Since July of 2009, The Compact Reconnaissance Imaging Spectral Mapper (CRISM) onboard the Mars Reconnaissance Orbiter (MRO) has periodically obtained pole-to-pole observations (i.e., full MRO orbits) of limb scanned visible/near IR spectra (λ=0.4-4.0 μm, △λ ∼ 10 nm- Murchie et al., 2007). These CRISM limb observations support the first seasonally and spatially extensive set of Mars 1.27 μm O2(1g)dayglow profile retrievals (∼ 1100) over ≥ 8 to 80 km altitudes. Their comparison to Laboratoire de Météorologie Dynamique (LMD) global climate model (GCM) simulated O2(1g)volume emission rate (VER) profiles, as a function of altitude, latitude, and season (solar longitude, Ls), supports several key conclusions regarding Mars atmospheric water vapor (which is derived from O2(1g)emission rates), Mars O3, and the collisional de-excitation of O2(1g)in the Mars CO2 atmosphere. Current (Navarro et al., 2014) LMDGCM simulations of Mars atmospheric water vapor fall 2-3 times below CRISM derived water vapor abundances at 20-40 km altitudes over low-to-mid latitudes in northern spring (Ls=30-60°), and northern mid-to-high latitudes over northern summer (Ls=60-140°). In contrast, LMDGCM simulated water vapor is 2-5 times greater than CRISM derived values at all latitudes and seasons above 40 km, within the aphelion cloud belt (ACB), and over high-southern to mid-northern latitudes in southern summer (Ls=190-340°) at 15-35 km altitudes. Overall, the solstitial summer-to-winter hemisphere gradients in water vapor are reversed between the LMDGCM modeled versus the CRISM derived water vapor abundances above 10-30 km altitudes. LMDGCM-CRISM differences in water vapor profiles correlate with LMDGCM-CRISM differences in cloud mixing profiles; and likely reflect limitations in simulating cloud microphysics and radiative forcing, both of which restrict meridional transport of water from summer-to-winter hemispheres on Mars (Clancy et al., 1996; Montmessin et al., 2004; Steele et al., 2014; Navarro et al., 2014) and depend on uncertain cloud microphysical properties (Navarro et al., 2014). The derived low-to-mid latitude changes in Mars water vapor vertical distributions should reduce current model-data disagreements in column O3 and H2O2 abundances over low-to-mid latitudes (e.g., within the ACB; Lefèvre et al., 2008; Encrenaz et al., 2015; Clancy et al., 2016). Lastly, the global/seasonal average comparison of CRISM and LMDGCM O2(1g)VER below 20 km altitudes indicates a factor of ∼ 3 times lower value (0.25 x 10−20 cm3sec−1) for the CO2 collisional de-excitation rate coefficient of O2(1g)than derived recently by Guslyakova et al. (2016).
Complete list of metadatas

https://hal-insu.archives-ouvertes.fr/insu-01512291
Contributor : Catherine Cardon <>
Submitted on : Saturday, April 22, 2017 - 9:08:26 AM
Last modification on : Friday, August 2, 2019 - 2:30:11 PM

Identifiers

Citation

R. Todd Clancy, Michael D. Smith, Franck Lefèvre, Timothy H. Mcconnochie, Brad J. Sandor, et al.. Vertical profiles of Mars 1.27 μm O2 dayglow from MRO CRISM limb Spectra: Seasonal/global behaviors, comparisons to LMDGCM simulations, and a global definition for Mars water vapor profiles. Icarus, Elsevier, 2017, 293, pp.132-156. ⟨10.1016/j.icarus.2017.04.011⟩. ⟨insu-01512291⟩

Share

Metrics

Record views

347