Trace Gases Other than Ozone

Additional chemical losses due to water radical reactions 9.3 9.0 

Nitric oxide is quite rapidly oxidized to N02 by reaction with ozone. Nitrogen dioxide, in turn, is subject to photolysis whereby NO is regenerated. This leads to the following reaction sequence 

The situation has been discussed by Strobel (1971), Brasseur and Nicolet (1973), Frederick and Hudson (1979b), and Jackman et al. (1980). It appears that the flux of NO at the stratopause, either into or out of the mesosphere, is essentially negligible compared with the stratospheric NO production rate. 

The significance of NO to stratospheric ozone is due to the competition between N02 and 03 for oxygen atoms  

In these reactions NO is not consumed while it destroys ozone. Rather, NO acts as a catalyst to ozone destruction in a pure oxygen atmosphere. Because it is faster, the catalytic cycle proceeds several times during the same time interval in which the 03 loss reaction of the Chapman mechanism occurs once. 

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Ozone is an essential atmospheric trace substance. This gas plays an important role in the control of the radiation and heat balance of the stratosphere since it absorbs solar radiation with wavelengths shorter than about 0.3 jun. An important consequence of this absorption is that U V radiation lethal to living species does not reach the lower layers of the atmosphere. Because of the importance of atmospheric 03, its study started rather early. Junge (1963) mentions that Dobson and his associates measured total ozone (see later) beginning in the twenties by a European network consisting of six stations. Later, this network became world-wide and even the determination of the vertical distribution of 03 is now a routine measurement. Owing to these studies our knowledge of atmospheric ozone is rather substantial compared to that of other trace constituents. 

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