Carbon monoxide in the atmosphere

A comprehensive study of the global distribution of atmospheric CO is described. The essential results can be listed as follows: (1) In the upper troposphere of the northern hemisphere the CO mixing ratio varies between 0.10 and 0.15 ppm, with few exceptions. (2) In the planetary boundary layer over the North Atlantic and at high index situations over western Europe, the CO concentrations range from 0.16 to 0.30 ppm if local sources are avoided. (3) Mid-tropospheric data from the subtropics show no marked difference between the two hemispheres, which implies (at least for the southern hemisphere) the presence of important natural CO sources. (4) Surface waters of the Atlantic ocean from 10°S to 60°N at 30°W have CO concentrations 10 to 40 times higher than the atmospheric equilibrium values. Large portions of the oceans appear to act as an important source for atmospheric CO. (5) Measurements in the tropopause region of the northern hemisphere show rapid decrease of CO above the tropopause. It appears that the stratosphere is the major sink for tropospheric CO.