1 -- INTRODUCTION

1.1 Objectives

2 -- ASSESSMENT STUDIES: THE IMPORTANCE OF COMPUTER MODEL SIMULATIONS

2.1 Creating a Realistic Predictive Ozone Model

      2.1.1 Model extrapolations and impact assessments

      2.1.2 Ozone Hindcasting

2.2 Different Models For Different Tasks

3 -- MODEL ASSUMPTIONS AND TYPES

3.1 Physical and Chemical Processes

      3.1.1 Radiation and the Atmosphere

      3.1.2 Gas-phase chemistry

                    (1) Source gases

                    (2) Reservoir species

                    (3) Radical species

      3.1.3 Heterogeneous chemistry

      3.1.4 Dynamics

3.2 Three Stratospheric Ozone Photochemical Models

      3.2.1 The photochemical box model

               a) Description

                         1) Isolated parcel or "box" of air

                         2) Photochemical equilibrium inside the box

                         3) Diurnal cycles and photochemical equilibrium

               b) Uses

      3.2.2 The trajectory model

               a) Description

                         1) Mixing time scales and air parcel integrity

                         2) Spatial scales and air parcel integrity

               b) Uses

                         1) Back trajectories: history of an air parcel

                         2) Mixing and transport properties

                         3) Synoptic versus asynoptic maps

                         4) Transforming asynoptic maps into synoptic maps using trajectory models

      3.2.3 The zonal mean or 2-D model

               a) Description

                         1) Radiation and chemistry modules of a 2-D model

                         2) Dynamics module of a 2-D model

                         3) Representing eddy transport processes: diffusion versus advection

               b) Uses

                         1) Comparisons of observations to model-predicted CFC-12 distribution

                         2) Limitation of 2-D models: the ClO overprediction problem

                         3) Consequences of overprediction

                         4) Advantages of the 2-D model

4 -- THE FUTURE OF OZONE

4.1 CFC Production Phase-Out: the Political Process

4.2 Long-Term Ozone Trend Model Predictions

      4.2.1 World Meteorological Organization (WMO) assessments

      4.2.2 Trend predictions based on ensembles of models

               a) Predicting the past: hindcasting

               b) Predicting future trends by extrapolating hindcast trends

               c) Predicting future trends based on changing model inputs

               d) Limitations and uncertainties in predicting future trends

               e) Predicting Antarctic and Arctic ozone loss and recovery

      4.2.3 Jet travel and rocket launch impact on stratospheric ozone

REFERENCES