Some aspects of the coupling between radiation, chemistry, and dynamics in the stratosphere

<jats:p>A number of mechanisms involving interaction between radiation, photochemistry, and dynamics that may affect the thermal compositional or dynamical structure of the stratosphere are discussed. The effect of coupling between radiative transfer, photochemistry, and advection of ozone by stratospheric winds on the effective relaxation rate of temperature perturbations is illustrated through the use of four examples. It is shown that for the vertical structure typical of planetary waves, ozone fluctuations act to hasten the relaxation of temperature perturbations in the upper stratosphere and to slow the relaxation in the lower half of the stratosphere. Next, the coupling between chemical sources and sinks of ozone and advection of air by motions is discussed. A simple Lagrangian model is employed and related to results from Eulerian model studies. Emphasis is placed upon the large eddy transports produced at the transition level between dynamical and photochemical control of ozone and also upon the mean ozone increases which eddies can produce in regions where there are sharp gradients in both the equilibrium ozone mixing ratio and the relaxation time scale for ozone perturbations. Finally, the variations of the effective relaxation rate of temperature perturbations are shown to be potentially important in determining the mean structure of the stratosphere during the winter season. These variations in the relaxation of temperature perturbations result from ozone variations produced both by chemistry and motions. In particular, a rapid increase in the effective damping rate of planetary waves between the middle and upper stratosphere leads to a rapid increase with height of eddy heat transports produced by the coupling between radiation and dynamics. This in turn can produce a significant modification of the zonal mean structure of the upper stratosphere.</jats:p>