The Photochemically-Controlled Upper Stratosphere and Mesosphere 25-75 km

Observations have provided important support for much of the key chemistry controlling upper stratospheric and mesospheric ozone, not only in terms of measurements of, for example, the abundance and distribution of OH, CIO, NO2, and other trace gases as discussed in Chapter 5 (e.g., Conway et al, 2000 Waters et al, 1983 Anderson et al, 1977 Russell et al, 1996), but also through some direct and dramatic responses to perturbations, detailed in following sections. 

It is well known that the primary source of heat in the stratosphere and mesosphere is the absorption of solar ultraviolet radiation by ozone 

Such a description can serve as a useful guide, but its applicability is limited by several factors. Ozone plays some role in the emission of infrared radiation as well as in absorbing ultraviolet radiation, so that the relaxation rate in the above equation is also linked to ozone change. 

Further, a change in temperature will modify all temperature-dependent photochemical rates and hence will feed back to the ozone chemistry. This renders the temperature-ozone relation into a tightly coupled and non-linear system that can be better understood with the aid of some simple chemical arguments. If a pure oxygen atmosphere is assumed (see Chapter 5), the interaction between ozone density and temperature dependent rates is expressed by  

Based upon the known temperature dependencies of reactions k2 and k , we can write  

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