The impact of interannual variability on multi-decadal total ozone simulations

We have used a two-dimensional chemistry and transport model to study the effects of interannual dynamical variability on global total ozone for 1979-2006. Long term meteorological data from the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) reanalysis-2 project, and the European Center for Medium Range Weather Forecasts (ECMWF) reanalyses (ERA-40) are used to construct yearly dynamical fields for use in the model. The simulations qualitatively resolve much of the seasonal and interannual variability observed in long term global total ozone data,including fluctuations related to the quasi-biennial oscillation. We performed a series of model experiments to examine the sensitivity of the interannual variability, changes in halogen and volcanic aerosol loading, and the 11-year solar cycle in UV in controlling the muti-decadal ozone changes. Statistical regression is then used to isolate these signals in the observed and simulated time series. We will discuss the relative roles of these processes, and how the model compares with the observations in simulating these features.