Source-receptor relationships between East Asian sulfur dioxide emissions and Northern Hemisphere sulfate concentrations

J. Liu (1) , D. L. Mauzerall (1) , L. W. Horowitz (2)

1 Woodrow Wilson School of Public and Int. Affairs
2 GFDL - NOAA Geophysical Fluid Dynamics Laboratory

We analyze the effect of varying East Asian (EA) sulfur emissions on sulfate concentrations in the Northern Hemisphere, using a global coupled oxidant-aerosol model (MOZART-2). We conduct a base and five sensitivity simulations, in which sulfur emissions from each continent are tagged, to establish the source-receptor (S-R) relationship between EA sulfur emissions and sulfate concentrations over source and downwind regions. We find that from west to east across the North Pacific, EA sulfate contributes approximately 80%?20% of sulfate at the surface, but at least 50% at 500 hPa. In addition, EA SO₂ emissions account for approximately 30%?50% and 10%?20% of North American background sulfate over the western and eastern US, respectively. The contribution of EA sulfate to the western US at the surface is highest in MAM and JJA, but is lowest in DJF. Reducing EA SO₂ emissions will significantly decrease the spatial extent of the EA sulfate influence over the North Pacific both at the surface and at 500 mb in all seasons, but the extent of influence is insensitive to emission increases, particularly in DJF and JJA. We find that EA sulfate concentrations over most downwind regions respond nearly linearly to changes in EA SO₂ emissions, but sulfate concentrations over the EA source region increase more slowly than SO₂ emissions, particularly at the surface and in winter, due to limited availability of oxidants (mostly H₂O₂). We find that similar estimates of the S-R relationship for trans-Pacific transport of EA sulfate would be obtained using either sensitivity or tagging techniques. Our findings suggest that future changes in EA sulfur emissions may cause little change in the sulfate induced health impact over downwind continents but SO₂ emission reductions may significantly reduce the sulfate related climate cooling over the North Pacific and the United States.

Domaines: Océan, Atmosphère

J. Liu, D. L. Mauzerall, L. W. Horowitz. Source-receptor relationships between East Asian sulfur dioxide emissions and Northern Hemisphere sulfate concentrations. Atmospheric Chemistry and Physics Discussions, 2008, 8 (2), pp.5537-5561. ⟨hal-00304041⟩