Quasi-biennial oscillation and quasi-biennial oscillation–annual beat in the tropical total column ozone: A two-dimensional model simulation

The National Centers for Environmental Prediction–Department of Energy Reanalysis 2 data are used to calculate the monthly mean meridional circulation and eddy diffusivity from 1979 to 2002 for use in the California Institute of Technology–Jet Propulsion Laboratory two-dimensional (2-D) chemistry and transport model (CTM). This allows for an investigation of the impact of dynamics on the interannual variability of the tropical total column ozone for all years for which the Total Ozone Mapping Spectrometer and the Solar Backscatter Ultraviolet merged total ozone data are available. The first two empirical orthogonal functions (EOFs) of the deseasonalized and detrended stratospheric stream function capture 88% of the total variance on interannual timescales. The first EOF, accounting for over 70% of the interannual variance, is related to the quasi-biennial oscillation (QBO) and its interaction with annual cycles, the QBO-annual beat (QBO-AB). The 2-D CTM provides realistic simulations of the seasonal and interannual variability of ozone in the tropics. The equatorial ozone anomaly from the model is close to that derived from the observations. The phase and amplitude of the QBO are well captured by the model. The magnitude of the QBO signal is somewhat larger in the model than it is in the data. The QBO-AB found in the simulated ozone agrees well with that in the observed data.