Atmospheric Trends of Carbon Monoxide (CO) by Khalil and Rasmussen

Carbon monoxide (CO) is a weak greenhouse gas but it is an important
precursor to tropospheric ozone (O3) and other trace gases in the
Earth's atmosphere, which can cause widespread changes in tropospheric
chemistry, global warming, and other climatic changes. Hydroxyl (OH)
radicals in the global atmosphere are removed primarily through
reactions with CO. OH radicals remove many man-made and natural trace
gases from the atmosphere including halocarbons and hydrocarbons.
Increases in CO may lead to decreases in OH allowing manmade and
natural trace gases to build up in the atmosphere. Nearly half of the
estimated amount of CO in the atmosphere is due to anthropogenic
sources such as automobile emissions, fossil fuel combustion, and
biomass burning (Logan et al, 1981). Concentrations of CO have
probably doubled since pre-industrial times and is increasing at an
annual rate between 0.8% and 1.4% (Khalil and Rasmussen, 1988).

Khalil and Rasmussen at the Oregon Graduate Institute have collected
over 60,000 CO measurements from the remote site at Cape Meares,
Oregon on the Pacific coast (Khalil and Rasmussen, 1984) from
1979-1983. CO was measured using an automated gas chromatograph
equipped with a methanotor and flame ionization detector. Later
observations were obtained at other sites around the globe including
Barrow (Alaska), Cape Meares (Oregon), Hawaii(Cape Kumukahi and Mauna
Loa), American Samoa (Pacific Ocean), Tasmania (Australia), Mawson (Antarctica)
and South Pole. The database consists of monthly CO concentrations in
parts per billion by volume (ppbv) from ecah site including
observations from Cape Meares (1979-1983). A global average CO
concentration was determined from trend analyses of the data collected
at these sites.