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Herein we provide a description of the atmospheric infrared sounder (AIRS) version 5 (v5) carbon monoxide (CO) retrieval algorithm and its validation with the DACOM in situ measurements during the INTEX-A and -B campaigns. All standard and support products in the AIRS v5 CO retrieval algorithm are documented. Building on prior publications, we describe the convolution of in situ measurements with the AIRS v5 CO averaging kernel and first-guess CO profile as required for proper validation. Validation is accomplished through comparison of AIRS CO retrievals with convolved in situ CO profiles acquired during the NASA Intercontinental Chemical Transport Experiments (INTEX) in 2004 and 2006. From 143 profiles in the northern mid-latitudes during these two experiments, we find AIRS v5 CO retrievals are biased high by 6%–10% between 900 and 300 hPa with a root-mean-square error of 8%–12%. No significant differences were found between validation using spiral profiles coincident with AIRS overpasses and in-transit profiles under the satellite track but up to 13 h off in time. Similarly, no significant differences in validation results were found for ocean versus land, day versus night, or with respect to retrieved cloud top pressure or cloud fraction. [ABSTRACT FROM AUTHOR]

We use recent aircraft measurements of a comprehensive suite of anthropogenic halocarbons, carbon monoxide (CO), and related tracers to place new constraints on North American halocarbon emissions and quantify their global warming potential. Using a chemical transport model (GEOS-Chem) we find that the ensemble of observations are consistent with our prior best estimate of the U.S. anthropogenic CO source, but suggest a 30% underestimate of Mexican emissions. We develop an optimized CO emission inventory on this basis and quantify halocarbon emissions from their measured enhancements relative to CO. Emissions continue for many compounds restricted under the Montreal Protocol, and we show that halocarbons make up an important fraction of the total greenhouse gas source for both countries: our best estimate is 9% (uncertainty range 6-12%) and 32% (21-52%) of equivalent CO2 emissions for the U.S. and Mexico, respectively, on a 20 year time scale. Performance of bottom-up emission inventories is variable, with underestimates for some compounds and overestimates for others. Ongoing methylchloroform emissions are significant in the U.S. (2.8 Gg/y in 2004-2006), in contrast to bottom-up estimates (<0.05 Gg), with implications for tropospheric OH calculations. Mexican methylchloroform emissions are minor. [ABSTRACT FROM AUTHOR]