A two-dimensional model with input parameters from a general circulation model - Ozone sensitivity to different formulations for the longitudinal temperature variation

Net heating and temperature derived from the middle atmospheric version of the NCAR's Community Climate Model (MA CCM2) history tapes are used to evaluate three different approaches to account for zonal temperature asymmetries in the calculation of gas phase and heterogeneous chemical reaction rate constants and polar stratospheric cloud (PSC) surface area in a 2D chemistry transport model (2D CTM). The first method uses the daily (and monthly) averaged 3D temperature distribution derived from the MA CCM2 to calculate chemical and heterogeneous reaction rates at each 3D grid point, followed by zonal averaging (pseudo-3D method). The second method uses 3D daily temperature statistics from the MA CCM2 to calculate the monthly averaged probability function (stochastic approach). The third method is based on a planetary wave superposition on the zonally averaged temperature (wave approach). The sensitivity of the gas phase reactions to the longitudinal temperature asymmetry is small, while the sensitivity of the heterogeneous reaction rates is comparable to the ozone response to aircraft emissions. All three methods of accounting for longitude temperature asymmetry give similar PSC morphologies in the Southern Hemisphere, in good agreement with climatological data and independent model calculations. (Author)