The Contribution of Global Transport on North American Carbon Monoxide Concentrations

Carbon Monoxide

Ehlers, Susanna

University of Wisconsin

关键词: Carbon Monoxide;   

Others  :  https://minds.wisconsin.edu/bitstream/handle/1793/35928/license_rdf?sequence=4&isAllowed=y

瑞士|英语

来源: University of Wisconsin

【 摘 要 】

Carbon monoxide, CO, is produced by natural and anthropogenicprocesses including biomass burning and fossil fuel usage and affectsatmospheric chemistry through its roles as a sink for the hydroxyl radical(OH) and as a precursor to ozone. As the primary atmospheric sink forOH, which is responsible for chemically destroying numerous airpollutants, CO concentrations impact the concentrations of other suchpollutants. Here we use CO as a tracer for polluted air masses byexamining the transport of CO both to and from North America.CO is an ideal tracer for atmospheric and climate modeling becauseit is well understood and well captured due to its simple chemistry andlong lifespan. By employing MOZART, a numerical global troposphericchemistry model, we seek to address the nature of air pollutant transportand establish the role of transport on regional North American COconcentrations. We find that the greatest intercontinental transported COoccurs on days when the overall carbon monoxide concentrations are lowto moderate. In addition, carbon monoxide concentrations increaseeastward, reflecting the different regional impacts of emissions.We also define three main transport pathways of CO over NorthAmerica and identify specific episodic flux events by comparing modelresults to INTEX-NA flight observations taken the summer of 2004 incooperation with NASA, NOAA, and the ICARn campaign. The mainpathways of CO transport over North America are eastward, aloft importfrom Asia; northward, surface import from Africa, attributed to heavybiomass burning in the summer; and eastward export from NorthAmerica, at the surface and aloft.Understanding these pathways for CO transport and the regionalimpacts is a key step towards understanding how polluted air massesevolve and can provide insight into the extent to which local air quality isinfluenced by intercontinental transport.