Average concentrations of OH in the troposphere, and the budgets of CH 4, CO, H 2 and CH 3CCl 3

Abstract

An average tropospheric OH concentration in the Northern Hemisphere of about 3 × 10 5 cm −3 is not in disagreement with present photokinetic information. This has important implications for the tropospheric budgets of CH 4, CO, H 2 and CH 3CCl 3. Present concentrations of CH 4 and H 2 in the atmosphere may be substantially larger than those prevailing during the pre‐industrial era, implying also an increase in H 2O concentrations and a decrease in ozone concentrations in the upper stratosphere. Accepting this estimate of an OH concentration and an important CO sink at the ground ( Seiler , 1974), there must be additional sources of CO than considered in presently evaluated budgets.