The Contribution of Global Transport on North American Carbon Monoxide Concentrations
Abstract
Carbon monoxide, CO, is produced by natural and anthropogenic
processes including biomass burning and fossil fuel usage and affects
atmospheric chemistry through its roles as a sink for the hydroxyl radical
(OH) and as a precursor to ozone. As the primary atmospheric sink for
OH, which is responsible for chemically destroying numerous air
pollutants, CO concentrations impact the concentrations of other such
pollutants. Here we use CO as a tracer for polluted air masses by
examining the transport of CO both to and from North America.
CO is an ideal tracer for atmospheric and climate modeling because
it is well understood and well captured due to its simple chemistry and
long lifespan. By employing MOZART, a numerical global tropospheric
chemistry model, we seek to address the nature of air pollutant transport
and establish the role of transport on regional North American CO
concentrations. We find that the greatest intercontinental transported CO
occurs on days when the overall carbon monoxide concentrations are low
to moderate. In addition, carbon monoxide concentrations increase
eastward, reflecting the different regional impacts of emissions.
We also define three main transport pathways of CO over North
America and identify specific episodic flux events by comparing model
results to INTEX-NA flight observations taken the summer of 2004 in
cooperation with NASA, NOAA, and the ICARn campaign. The main
pathways of CO transport over North America are eastward, aloft import
from Asia; northward, surface import from Africa, attributed to heavy
biomass burning in the summer; and eastward export from North
America, at the surface and aloft.
Understanding these pathways for CO transport and the regional
impacts is a key step towards understanding how polluted air masses
evolve and can provide insight into the extent to which local air quality is
influenced by intercontinental transport.
Subject
Carbon Monoxide
Permanent Link
http://digital.library.wisc.edu/1793/35928Type
Thesis
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