The Potential effects of increased methane on atmospheric ozone (original) (raw)

1982, Geophysical Research Letters

Using a one dimensional atmospheric Miller et al. (1981) and the references found model, we investigate the possible influence of an therein. For these calculations, 30 chemical increase in atmospheric methane on ozone. The species were active, including all those currently couplings between methane and the catalytic identified as important to methane and ozone destruction of ozone by NO., HOx, and C1X are chemistry in the troposphere and stratosphere. discussed. Our model calculations suggest that Recent updates to the model include the addition doubling the ground-level flux of methane, with of clouds in the troposphere (50% cloud cover at 6 fixed atmospheric temperatures and currently km altitude) and the calculation of UV penetration recommended chemical reaction rates, would in the Schumann-Runge bands of molecular oxygen increase the total ozone column by 3.5%. based on the formulation of Frederick and Hudson Calculations showing the very significant (1980). The chemical reaction rates and incident moderating effects of a methane increase on ozone solar fluxes are those recommended by recent NASA perturbations due to N20 and chlorofluorocarbons panels (WMO, 1982). are discussed. The "initial" atmosphere used as a basis for comparison is one with no chlorofluorocarbons through a "greenhouse effect" similar to that of tropospheric methane mixing ratio were to increase CO 2 (Wang et al., 1980). Such atmospheric at a rate of 1-2% per year, as recent measurements temperature changes, which we will not discuss suggest, this source strength would be reached in here, can also perturb stratospheric chemistry. 50-100 years. The methane concentration in the 2 x CH• atmosphere is a factor of 2.8 larger than the The Impact of Increased Methane on Atmospheric initial case at the ground and 2.2 in the upper Chemistry stratosphere. The one-dimensional atmospheric chemistry and The atmospheric chemistry of methane is transport model used here has been described in complex, particularly in the troposphere (see, eg., Ehhalt and Schmidt, 1978, Logan et al., 1981). A one-dimensional model cannot properly Copyright 1982 by the American Geophysical Union. simulate the latitudinal variations of species Paper number 2Ll122. like CO, NO, and OH that are important in 0094-8276/82/002L-112253.O0 tropospheric chemistry (Logan et al., 1981).