A zonally averaged time dependent primitive equation model has been used to simulate the dispersion of both a carbon 14 injection and the volcanic aerosol from the 1974 Fuego eruption. Both injections occurred at low latitudes to mid-latitudes in the northern hemisphere. The eddy flux terms, which provide the major portion of the transport in lower stratosphere of this model, are specified in a manner similar to Harwood and Pyle. Comparisons with data emphasize the ability of the model to simulate the vertical character of the tracer, while maintaining reasonable meridional transport times. For the aerosol study, the simulated 1/e decay time at 37¿ N and for the 16-to 21-km altitude region is 9 months, whereas lidar measuremtns at the same latitude yield a decay time of 8 months. The simulated vertical width at half-maximum for the aerosol tracer at 37¿ N and 19¿ N and for 6 months after the event has values of 5.0 km and 3.6 km, respectively, whereas the observed lidar values were 4.4 km and 3.0 km, respectively. Tracer transport to the southern hemisphere also agrees qualitatively with the limited data that are available. Comparisons of our model results with those published using other zonally averaged models indicate that there are major differences in the transport in parameterized zonally averaged models. For the present model, inclusion of a realistic aerosol sedimentation rate moves the vertical position of the model layer peak onto the observed one. The close agreement between data and our model results show that one does not have to invoke aerosol chemical growth processes in order to model the dispersion of this aerosol tracer from 2 months to 1 year after the event.