HR: 0830h
AN: A11F-0060    [PDF]
TI: Changes in Tropospheric Carbon Monoxide During the Past Century
AU: * Novelli, P C
EM: Paul.C.Novelli@noaa.gov
AF: NOAA/CMDL, DSRC 325 Broadway, Boulder, CO 80305
AB: Future changes in the abundance atmospheric carbon monoxide (CO) have the potential to exert significant effects on the earths radiative balance. Although CO is not strong absorber of infrared radiation, and thus not considered a greenhouse gas, the photochemically-driven cycle of CO provides it with an indirect greenhouse effect similar in magnitude to that of nitrous oxide ($\sim$10% that of CO$_[2]$). This paper will examine CO trends over the past 100 years derived from ice core data, from total column measurements, and from recent global surface measurements. Determination of long-term CO trends is complicated by several factors, including the precision of available measurement techniques, their long term stability, and significant year to year variability in CO. The available data suggest a strong anthropogenic influence on tropospheric CO; particularly in the Northern Hemisphere (fewer data are available for the Southern Hemisphere). Recent measurements show a high degree of interannual variability which dramatically impacts short term growth rates. Long term changes are more difficult to quantify. Although the magnitudes of the individual sources comprising the global budget of CO contain large uncertainties, we find that human activity impacts the three major CO sources (combustion of fossil fuel and biomass, and methane oxidation). Natural events, such as volcanic eruptions, also may affect CO. The major sink of CO, reaction with the hydroxyl radical (OH), is found to efficiently scavenge short-lived pulses of CO to the atmosphere. Long term trends in CO are small (relative to the increase in emissions) suggesting tropospheric CO is strongly buffered by OH.
DE: 0322 Constituent sources and sinks
DE: 0345 Pollution--urban and regional (0305)
DE: 0365 Troposphere--composition and chemistry
DE: 1610 Atmosphere (0315, 0325)
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting