Quantifying the contributions of natural emissions to ozone and total fine PM concentrations in the Northern Hemisphere 1Department of Environmental Science, Aarhus University, Aarhus, Denmark
17 Mar 2014
2Institute of Geophysics, University of Tehran, Tehran, Iran
3AU Herning, Aarhus University, Aarhus, Denmark
4Department of Chemistry and iNANO, Aarhus University, Aarhus, Denmark
Received: 13 May 2013 – Published in Atmos. Chem. Phys. Discuss.: 21 Jun 2013Abstract. Accurate estimates of emissions from natural sources are needed for reliable
predictions of ozone and fine particulate matter (PM2.5) using air
quality models. In this study, the large-scale atmospheric chemistry
transport model, DEHM (the Danish Eulerian Hemispheric Model) is further
developed, evaluated and applied to study and quantify the contributions of
natural emissions of VOCs, NOx, NH3, SO2, CH4, PM, CO
and sea salt to the concentration of ozone and formation of PM2.5 for
the year 2006. Natural source categories adopted in the recent model are
vegetation, lightning, soils, wild animals and oceans. In this study, the
model has been further developed to include more Biogenic Volatile Organic
Compounds (BVOCs) and to implement a scheme for secondary organic aerosols
as well as an updated description of sea-salt emissions. Our simulations
indicate that in the Northern Hemisphere the contribution from natural emissions
to the average annual ozone mixing ratios over land is between 4–30 ppbV.
Among the natural emissions, BVOCs are found to be the most significant
contributors to ozone formation in 2006, enhancing the average ozone mixing
ratio by about 11% over the land areas of the Northern Hemisphere. The
relative contribution of all the natural emissions to ozone is found to be
highest in the northern part of South America by about 42%. Similarly,
the highest contribution of all the natural sources to total fine particles
over land is found to be in South America by about 74% and sea-salt
aerosols demonstrated to play the most important role. However, over the
rest of the regions in the model domain the largest contribution from the
natural sources to PM2.5 in the specific year 2006 is due to wildfires.
The contribution from natural emissions to the mean PM2.5 concentration
over the land areas in the model domain is about 34%.
Revised: 24 Jan 2014 – Accepted: 05 Feb 2014 – Published: 17 Mar 2014
Citation: Zare, A., Christensen, J. H., Gross, A., Irannejad, P., Glasius, M., and Brandt, J.: Quantifying the contributions of natural emissions to ozone and total fine PM concentrations in the Northern Hemisphere, Atmos. Chem. Phys., 14, 2735-2756, doi:10.5194/acp-14-2735-2014, 2014.