Trace gases in the middle atmosphere are subject to chemical transformations as well as to transport. A study of these processes occurring simultaneously in the atmosphere is performed using a three-dimensional hemispheric model based on the primitive equations to which a chemical scheme is added. The model results exhibit the gross features seen in the real atmosphere during a simulated wave number 1 warming, including the transport of chemically active trace species such as ozone, nitric acid, and nitrogen oxides. The model simulation suggests that the polar vortex behaves as a material entity during the planetary wave disturbance. At the same time, poleward transport is accomplished through tongues of tracers originating in the subtropics. Finally, scale interaction leads to mixing into even smaller scales, flattening gradients of tracer mixing ratios at mid-latitudes, while steepening them at the edge of the vortex. The relative influences of chemistry and dynamics on the distribution of these gases are investigated. The effect of nonlinearity on the transport is addressed. ¿ American Geophysical Union 1989