Total column and surface densities of atmospheric carbon monoxide in Alaska, 1995

The results of correlated investigations of atmospheric carbon monoxide in Alaska during the spring-summer of 1995 using three different techniques are presented. CO total column abundance was measured in Fairbanks using IR spectroscopy with the Sun as a light source. A new computer retrieval code was developed and compared with the previously used technique. Surface mixing ratios were determined in situ by gas filter correlation and by gas chromatography with a mercuric oxide reduction detector. Surface measurements were made at two uncontaminated sites: Poker Flat Research Range in interior Alaska and the National Oceanic and Atmospheric Administration Point Barrow Observatory. In spring, the measurements revealed considerably more CO in the surface layer as compared with the tropospheric mean values determined by spectroscopy. This suggests an accumulation of anthropogenic CO in the boundary atmospheric layer over vast areas of the northern hemisphere during the winter. Beginning in mid-April, the CO concentration in the troposphere decreases, but the rate of decrease in the surface layer was 2-2.5 times greater than that for the troposphere as a whole. By June the surface mixing ratios and mean tropospheric values nearly converged, and the CO mixing ratio seemed to be almost constant with altitude. The July measurements revealed days with enhanced CO total column burden; these are most likely associated with lifted layers of air, polluted by forest fires.