Attribution of direct ozone radiative forcing to spatially resolved emissions

[1] Quantifying the dependence of ozone direct radiative forcing (DRF) on the mixture and spatial distribution of precursor emissions is a key step towards understanding the impact of air quality standards on climate. We use here a combination of satellite observations of ozone and its radiative effect in conjunction with an adjoint chemical transport model to determine the ozone DRF due to global, anthropogenic NOx, CO, and non-methane hydrocarbons (NMHC) emissions regionally at 2 2.5 regions resolution. We show that 8% of the ozone DRF from the sum of all these emissions can be attributed to 15 regions, which are predominantly located in China and the United States (US). To achieve an equivalent reduction in ozone DRF, necessary emission reductions for each precursor vary intra-continentally by a factor of 3–10 and globally by over an order of magnitude. The contribution of NOx emissions to ozone DRF relative to CO and NMHC emissions within individual regions varies globally by nearly a factor of two. Citation: Bowman, K., and D. K. Henze (2012), Attribution of direct ozone radiative forcing to spatially resolved emissions, Geophys. Res. Lett., 39, L22704, doi:10.1029/2012GL053274.