Millimeter observations of Mars with the IRAM 30-m antenna : Constraints on CO, T(P), and zonal winds

Introduction: Observations of Mars in the submillimeter range have been performed for almost 30 years (Kakar et al, 1977). CO (1-0) and (2-1) transitions (at 115 and 230 GHz respectively) have been used, together with the CO (1-0) and (2-1) transitions (at 110 and 220 GHz respectively), to constrain the CO mixing ratio and the temperature profile (Clancy et al., 1983, 1990). In addition, a CO mapping of the martian disk has been made in the (1-0) and (2-1) lines of CO (Lellouch et al., 1991a). No variations higher than 40% were recorded over the martian disk, and a mean CO mixing ratio of 8+/2 10 was inferred. Observations made in the IR range during 1988-89 and 1990-91 in the (1-0) and (2-0) vibrational bands (Billebaud et al., 1992, 1998) led to mean values of CO of 6.2 +/2 10 and 8.5 +/3 10 respectively. Later, from the reduction of an ISO-SWS averaged spectrum of Mars, a mixing ratio of 7 10 was inferred (Lellouch etal., 2001). Later on, the CO millimeter transitions were used to constrain the thermal profile (in addition to the GCM model), assuming a constant CO mixing ratio of 7 10 , in order to determine the water vapor vertical profile from HDO and H2O millimeter transitions (Encrenaz et al., 2001), or from the H2O submillimeter transition at 557 GHz (Biver et al., 2005).