Model-calculated carbon monoxide. Top (bottom) panel shows upper (lower) tropospheric
distribution during September 1993.
Atmospheric carbon monoxide (CO) has four major sources: biomass burning,
fossil fuel combustion, nonmethane hydrocarbon oxidation, and methane
oxidation. Its primary loss mechanism is reaction with the hydroxyl radical
(OH). Globally, CO is important because its oxidation by OH is a major source of