Welcome to the Harvard Atmospheric Chemistry Modeling Group!

Our goal is to understand the chemical composition of the atmosphere, its perturbation by human activity, and the implications for climate change and life on Earth. We address this goal through global modeling of atmospheric chemistry and climate, aircraft measurement campaigns, satellite data retrievals, and analyses of atmospheric observations.

GROUP LEADERS: Daniel J. Jacob, Jennifer A. Logan, Loretta J. Mickley, Elsie Sunderland

January 2012: Intercontinental enhancement of particulate matter from NO_x and CO emissions

We show that anthropogenic emissions of nitrogen oxides (NO_x = NO + NO₂) and carbon monoxide (CO) affect particulate matter (PM) air quality on an intercontinental scale by changing background concentrations of oxidants (OH, ozone, H₂O₂) and thus increasing the oxidation rate of sulfur dioxide (SO₂) to sulfate and NO_x to nitrate. In fact, the intercontinental influences of NO_x and CO emissions on PM can be greater than those from SO₂ emissions (a direct PM precursor). The intercontinental impact of oxidant precursors is greatest in receptor regions with high domestic SO₂, NO_x, and ammonia emissions and hence already high levels of PM. US NO_x and CO emissions increase annual mean PM in northern Europe and eastern China by up to 0.25 μg m^-3. The increase in Europe is mostly as sulfate, whereas in China it is mostly as nitrate. East Asian NO_x and CO emissions have a weaker intercontinental influence (~0.2 μg m^-3 in northern Europe, ~0.1 μg m^-3 in the eastern US). For more information, see Leibensperger et al. [2011].

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