SEPTEMBER 2002: Particulate Matter Controls Could Increase Surface Ozone over Europe and Other Industrial Regions

The above figure shows the sensitivity of lower tropospheric (~600 m) OH and O₃ in August to photochemical effects of aerosols not usually included in global models: (1) aerosol scattering and absorption of ultraviolet radiation, and (2) reactive uptake of HO₂, NO₂, and NO₃. We calculate this effect by coupling a global 3D model of tropospheric chemistry (GEOS-CHEM) with aerosol fields from a global 3D aerosol model (GOCART). Annual mean OH concentrations decrease by 9% globally and by 5-35% in the boundary layer over the Northern Hemisphere. Simulated CO increases by 5-15 ppbv in the remote Northern Hemisphere, improving agreement with observations. Simulated boundary-layer O₃ decreases by 15-45 ppbv over India during the biomass burning season in March, and by 5-9 ppbv over northern Europe in August, again improving comparison with observations. This work was led by Randall Martin. A full account is given in our recently accepted manuscript Martin et al. [2002].