Effects of Atmospheric Chemical and Climate Change on Tropospheric Ozone

Abstract

Abstract Changes in atmospheric levels of certain pollutants (CH4, CO, NOX, nonmethane hydrocarbons) have the potential to affect tropospheric O3 formation and the abundance of the free radical OH on a global scale. Perturbations to stratospheric O3 and climate (temperature and moisture) also can influence tropospheric O3 and OH. We have used a tropospheric photochemical model with projections of CO, NOX, and CH4 to predict tropospheric ozone and OH changes from 1980-2030. The calculations simulate the background chemistry of various global regions and assume that increases in CH4 and CO will continue at current rates. Predicted changes in tropospheric O3 and OH are different in urban and nonurban areas, and in marine and continental regions. Generally, increasing levels of CH4 and CO at constant NOX levels will increase O3 and suppress OH. A rough estimate of possible global changes shows tropospheric O3 increasing ˜10% from 1980 to 2030 and OH decreasing ˜10% during that period. When calculations are pe...