Re: the term steady state as to the concentration of ozone in stratosphere

The "state" of the atmospheric ozone means the instantaneous 3-D distribution of ozone through the atmosphere. All of the sources and sinks have specific vertical and temporal profiles, for instance UV radiation from the sun creates ozone at the top of the stratosphere, while chemical reactions involving air pollution create ozone in the mid-troposphere.

Chemical destruction of ozone occurs at all levels, by a variety of mechanisms. A "steady state" is the state of the atmosphere when these processes of creation and destruction balance each other out. Note that in the case of ozone, many of the processes involved are sunlight-dependent and thus have a seasonal profile, so a true instantaneous "steady state" is never achieved. However, in this case the notion of "steady state" is expanded to include the full seasonal cycle: that is, in a "steady state" one would expect the state on 1 March 2010 to be identical to the state on 1 March 2009.