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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 112, D10312, doi:10.1029/2006JD007826, 2007

Sensitivity of global sulphate aerosol production to changes in oxidant concentrations and climate

J. G. L. Rae

Met Office, Hadley Centre for Climate Change, Exeter, Devon, UK


C. E. Johnson

Met Office, Hadley Centre for Climate Change, Exeter, Devon, UK


N. Bellouin

Met Office, Hadley Centre for Climate Change, Exeter, Devon, UK


O. Boucher

Met Office, Hadley Centre for Climate Change, Exeter, Devon, UK


J. M. Haywood

Met Office, Hadley Centre for Climate Change, Exeter, Devon, UK


A. Jones

Met Office, Hadley Centre for Climate Change, Exeter, Devon, UK


Abstract

The oxidation of SO2 to sulphate aerosol is an important process to include in climate models, and uncertainties caused by ignoring feedback mechanisms affecting the oxidants concerned need to be investigated. Here we present the results of an investigation into the sensitivity of sulphate concentrations to oxidant changes (from changes in climate and in emissions of oxidant precursors) and to changes in climate, in a version of HadGAM1 (the atmosphere-only version of HadGEM1) with an improved sulphur cycle scheme. We find that, when oxidants alone are changed, the global total sulphate burden decreases by approximately 3%, due mainly to a reduction in the OH burden. When climate alone is changed, our results show that the global total sulphate burden increases by approximately 9%; we conclude that this is probably attributable to reduced precipitation in regions of high sulphate abundance. When both oxidants and climate are changed simultaneously, we find that the effects of the two changes combine approximately linearly.

Received 2 August 2006; accepted 26 February 2007; published 25 May 2007.

Keywords: Sulphate aerosol; sulphur cycle.

Index Terms: 0325 Atmospheric Composition and Structure: Evolution of the atmosphere (1610, 8125); 0365 Atmospheric Composition and Structure: Troposphere: composition and chemistry; 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801, 4906).

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Citation: Rae, J. G. L., C. E. Johnson, N. Bellouin, O. Boucher, J. M. Haywood, and A. Jones (2007), Sensitivity of global sulphate aerosol production to changes in oxidant concentrations and climate, J. Geophys. Res., 112, D10312, doi:10.1029/2006JD007826.