Variability of carbon monoxide in the Mars atmosphere
Recent measurements and reanalyses of past measurements are used to derive estimates of the variability of CO concentrations in the Martian atmosphere. The J = 1 - 2 rotational transition of CO in the microwave spectrum of Mars was observed in January, 1982, and abundances were calculated through surface and atmospheric temperature modeling. A column density of 4.6 + or - 2.0 x 10 to the 20th/sq cm is obtained, which is contrasted with values of 3.0 + or - 1.0 x 10 to the 20th/sq cm in 1980 and 1.7 x + or - 0.9 x 10 to the 20th/sq cm in 1975 obtained by reanalysis of the J = 0 - 1 transition observed by Good and Schloerb (1981) and Kakar et al. (1977), respectively. It is noted that due to the uncertainties in global atmospheric average temperatures, results are consistent with a CO variability of from 0 to 100 percent over a time scale of several years. It is suggested that simultaneous measurements of the J = 0 - 1 and J = 1 - 2 transitions may provide stronger constraints on the CO abundance and atmospheric temperature of Mars.