Assessing Effects of Rate Parameter Changes on Ozone Models Using Sensitivity Analysis

Abstract

Effects of recommended rate parameter changes in the NASA JPL-2000 evaluation from JPL-94 values on local ozone concentrations in a 2-D model are predicted using local sensitivity analysis results from the LLNL 2-D diurnally averaged model. Ozone decreases of 5% in the middle stratosphere and 10% increases near the tropopause and upper troposphere are indicated. Altered NOx kinetics are largely responsible for these changes, and increased model NOx levels and ozone depletion from stratospheric aircraft are also expected according to sensitivity analysis. Effects of specific changes, such as the nitric acid formation rate, are examined. New error bars on rate parameters in the evaluation are propagated by the sensitivity coefficients to derive revised kinetics uncertainties for the model ozone calculations at several altitudes, latitudes, and seasons. Middle-upper stratospheric ozone uncertainties of 12% from the catalytic photochemistry are indicated, increasing in the lower stratosphere.