A coupled one‐dimensional radiative‐convective, chemistry‐transport model of the atmosphere: 1. Model structure and steady state perturbation calculations

Abstract

An atmosphere model composed of a narrow band radiative‐convective (RC) code coupled with a one‐dimensional chemistry and transport code is described. The RC model, formulated in log‐pressure coordinates, includes accurate solar absorption calculations for O 3 , O 2 , H 2 O, and CO 2 . Infrared heating and cooling by CO 2 , O 3 , and H 2 O are calculated with a narrow band formulation, while broader band formulations are used for CH 4 , N 2 O, CFC 11, and CFC 12. The atmospheric chemistry and transport model uses photochemical reaction rate data from Jet Propulsion Laboratory publication 82–57. The calculated steady state atmospheric response to several potential perturbations is discussed. Doubling the atmospheric CO 2 level yields a change in total ozone of +2.9% and a surface temperature increase of 1.7 K. The continued release of chlorofluorocarbons (CFC's) alone at nominal rates gives a calculated column ozone change of −5.7% at steady state, while for a combined 2×CO 2 +CFC perturbation the result is −3.5%. Ozone perturbations due to increases in N 2 O, CH 4 , and aircraft are also discussed. Two coupled scenarios including projected changes that may occur in about 100 years due to all these identified man‐made perturbations are discussed. The calculated ozone column changes are −4.5% and +1.5%, assuming fixed and doubled methane source strengths, respectively.