The correlation between anticyclone frequency and midlatitude ozone variability

Attribution and interpretation of ozone trends and variability requires knowledge of changes in stratospheric dynamics. One method commonly used to deduce the contributions of dynamical effects to ozone variability and trends is to separate ozone data based on sampled air mass type. Here we will analyze ozone distributions in three different air mass types-vortex, anticyclone, and ambient. This represents a significant improvement over previous work that considers only vortex and extra-vortex air masses, but fails to take into account the contribution of anticyclones to the extra-vortex air. This work will determine whether there is a correlation between stratospheric anticyclone frequency and observed ozone interannual variability. Data from EOS-MLS, as well as historical and ongoing data from occultation instruments, will be used in conjunction with simulations from the Whole Atmosphere Community Climate Model (WACCM). Taking advantage of the global sampling by the Aura instruments, we will provide an estimate of the extent to which anticyclones affect overall ozone variability. Global ozone distributions and the inferred dynamical contribution to ozone variability will then be compared to WACCM simulations. This will provide a valuable diagnostic check of both the model chemistry and dynamics. The information gained from the Aura investigation will be applied to analyses of the longer term, but geographically more sparse, occultation data, and to long-term WACCM simulations, to infer dynamical effects on ozone trends.