Deriving a Linearised Ozone Chemistry Scheme for a 3-D Chemical Transport Model of the Middle Atmosphere

Abstract

A simple but computer efficient parameterized ozone chemistry is developed to account for up-dates in reaction rate recommendations, and also completely assess the contributions of the indi-vidual catalytic cycles to the ozone budget in the entire stratosphere. Two conceptual ap-proaches, namely total time approach and rate limiting step approach, have been used to im-prove upon an existing comprehensive stratospheric chemistry model to calculate the coefficient of linearised ozone chemistry scheme. The total time approach is accurate in calculating for the coefficients of the ozone chemistry scheme whiles the rate limiting step approach is effective in assessing the contributions of the individual catalytic cycles to the ozone budget. The catalytic cycle with the rate limiting step of NO2/O is very prominent in altitudes between 15 and 48 km, and peaks at 30 km with ozone loss percentage contribution of about 75%. HO2/O rate limiting step dominates above 40 km and peaks around 58 km with about 90% loss contribution to the ozone budget. Rate limiting steps involving BrO were the least ozone loss reactions in the set at the chosen mid-latitude June condition, and they concentrate at the lower stratosphere.