Oxygenates upper troposphere

In the troposphere ozone is produced by photodissociation (equation 3) not of 02 but of N02, initiated with wavelengths <410 nm, followed by recombination (equation 2) with 02. In the upper troposphere and lower stratosphere the photolysis of ozone (equation 4) yields excited-state oxygen atoms which react with water to produce hydroxyl radicals (equation 5). These are crucial to the removal of organic compounds from the troposphere, since they readily abstract hydrogen atoms (equation 6) to yield organic radicals which subsequently undergo further oxidative degradation. 

The lifetime of odd oxygen in the middle and upper troposphere is much longer (one month or more) because the rate of removal via reaction (6) (O3 +hv 20H) depends on the availability of H2O. Typically, H2O mixing ratios in the middle and upper troposphere are lower than at ground level by a factor of 10 or more. 

If Reaction (5.53) is followed by N02 photolysis, N02 + hi/ —> NO + O, then the net effect is to produce odd oxygen. This reaction is an important source of ozone in the lower stratosphere and upper troposphere (see Crutzen, 1971). Methoxy is in turn destroyed by reaction with molecular oxygen ... 

Ozone forms in the upper stratosphere from molecular oxygen under the influence of UV solar radiation. In the lower stratosphere and troposphere, the source of ozone is the decomposition of nitrogen dioxide under the influence of UV and visible radiation. The formation of the vertical profile of ozone concentration is connected with its meridional and vertical transport. The general characteristic of this profile is the total amount of ozone measured by the thickness of its layer given in Dobson units (1 DU = 0.001 cm). 

Ozone is formed in both the upper (stratosphere) and lower (troposphere) sections of the earth atmosphere. Stratospheric O3 is generated by intensive ultraviolet light. The high energy of this radiation splits molecular O2 into oxygen atom radicals, O, which then react with oxygen molecules ... 

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