Perturbation to global tropospheric oxidizing capacity due to latitudinal redistribution of surface sources of NOx, CH4 and CO

Economic and social projections indicate that during next several decades there will be major geographical redistribution of surface emissions of O-3 precursors, such as NOx, CH4 and CO. A net decrease in their emissions from northern hemispheric mid-latitudes will be accompanied by substantial increases from the tropics. We have investigated a hypothetical scenario of currently underway transition of such emission patterns using a global two-dimensional photochemical model. With overall O-3 precursor releases held constant, a simultaneous transfer of their emissions by 25% from the latitude belt 75 degrees N-35 degrees N to 5 degrees S-35 degrees N increases tropospheric oxidizing capacity Such that the methane global lifetime and concentrations fall by more than 3%. Seasonally dependent changes in surface O-3 concentrations are also calculated. In influencing OH concentration, redistribution of surface NOx emissions is 2-3 orders of magnitude more efficient per unit mass than CO emissions. Shifts in methane sources have insignificant effects on global photochemistry, but lead to a decrease in its interhemispheric gradient.