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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 17, 14219-14237, 2017
https://doi.org/10.5194/acp-17-14219-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
30 Nov 2017
Multi-model impacts of climate change on pollution transport from global emission source regions
Ruth M. Doherty1, Clara Orbe2, Guang Zeng3, David A. Plummer4, Michael J. Prather5, Oliver Wild6, Meiyun Lin7,8, Drew T. Shindell9, and Ian A. Mackenzie1 1School of GeoSciences, University of Edinburgh, Edinburgh, EH9 3FF, UK
2Goddard Earth Sciences Technology and Research (GESTAR), Johns Hopkins University, Baltimore, MD 21218, USA
3National Institute of Water and Atmospheric Research, Wellington 6021, New Zealand
4Canadian Centre for Climate Modelling and Analysis, Environment and Climate Change Canada, Montréal, QC, Canada
5Department of Earth System Science, University of California, Irvine, Irvine, CA 92697-3100, USA
6Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK
7Program in Atmospheric and Oceanic Sciences at Princeton University, Princeton, NJ 08540, USA
8NOAA Geophysical Fluid Dynamics Laboratory, Princeton, NJ 08540, USA
9Nicholas School of the Environment, Duke University, Durham, NC 27708, USA
Abstract. The impacts of climate change on tropospheric transport, diagnosed from a carbon monoxide (CO)-like tracer species emitted from global CO sources, are evaluated from an ensemble of four chemistry–climate models (CCMs) contributing to the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP). Model time-slice simulations for present-day and end-of-the-21st-century conditions were performed under the Representative Concentrations Pathway (RCP) climate scenario RCP 8.5. All simulations reveal a strong seasonality in transport, especially over the tropics. The highest CO-tracer mixing ratios aloft occur during boreal winter when strong vertical transport is co-located with biomass burning emission source regions. A consistent and robust decrease in future CO-tracer mixing ratios throughout most of the troposphere, especially in the tropics, and an increase around the tropopause is found across the four CCMs in both winter and summer. Decreases in CO-tracer mixing ratios in the tropical troposphere are associated with reduced convective mass fluxes in this region, which in turn may reflect a weaker Hadley cell circulation in the future climate. Increases in CO-tracer mixing ratios near the tropopause are largely attributable to a rise in tropopause height enabling lofting to higher altitudes, although a poleward shift in the mid-latitude jets may also play a minor role in the extratropical upper troposphere. An increase in CO-tracer mixing ratios also occurs near the Equator, centred over equatorial and Central Africa, extending from the surface to the mid-troposphere. This is most likely related to localised decreases in convection in the vicinity of the Intertropical Convergence Zone (ITCZ), resulting in larger CO-tracer mixing ratios over biomass burning regions and smaller mixing ratios downwind.

Citation: Doherty, R. M., Orbe, C., Zeng, G., Plummer, D. A., Prather, M. J., Wild, O., Lin, M., Shindell, D. T., and Mackenzie, I. A.: Multi-model impacts of climate change on pollution transport from global emission source regions, Atmos. Chem. Phys., 17, 14219-14237, https://doi.org/10.5194/acp-17-14219-2017, 2017.
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Short summary
We investigate how climate change impacts global air pollution transport. To study transport changes, we use a carbon monoxide (CO) tracer species emitted from global sources. We find robust and consistent changes in CO-tracer distributions in climate change simulations performed by four chemistry–climate models in different seasons. We highlight the importance of the co-location of emission source regions and controlling transport processes in determining future pollution transport.
We investigate how climate change impacts global air pollution transport. To study transport...
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