The PIs will determine whether the observed quasi-decadal oscillation (QDO) in ozone is a result of interannual changes in dynamical transport of ozone resulting from the observed QDO in stratospheric circulation. This would help develop a self-consistent theoretical model of the QDO. Using a series of updated data records, they will first determine the QDO in stratospheric ozone, temperature, geopotential height, and zonal wind. They will apply observationally derived regression coefficients for vertical/meridional temperature gradients and geopotential heights to construct zonal wind and temperature gradient anomalies for each phase of the quasi-biennial oscillation (QBO) and QDO. Then, they will modify the NCAR two-dimensional chemical transport model for zonal mean circulation and temperature gradient field specification for each month and phase of the QBO and QDO. Resulting mean meridional circulation and ozone distributions will be calculated as a function of month, latitude and pressure level. Finally, the differences between calculated ozone distributions will produce an effective model-predicted ozone QDO's construction for comparison to observed ozone QDO.
