An analysis is made of the various reactions in which ozone and atomic oxygen are involved in the stratosphere. At the present time, hydrogen, nitrogen, and chlorine compounds in the ranges parts per million, parts per billion, and parts per trillion may have significant chemical effects. In the upper stratosphere, above the ozone peak, where there is no strong departure from photochemical equilibrium conditions, the action of hydroxyl and hydroperoxyl radicals of nitrogen dioxide and chlorine monoxide on atomic oxygen and of atomic chlorine on ozone can be introduced. A precise determination of their exact effects requires knowledge of (1) the vertical distribution of the H2O, CH4, and H2 dissociation by reaction of these molecules with electronically excited oxygen atom O(¹D); (2) the ratio of the OH and HO2 concentrations and their absolute values, which depend on insufficiently known rate coefficients; (3) the various origins of nitric oxide production, with their vertical distributions related to latitude and season; and (4) the various sources giving different chlorine compounds that may be dissociated in the stratosphere. In the lower stratosphere, below the ozone peak, there is no important photochemical production of O3, but there exist various possibilities of transport. The predictability of the action of chemical reactions depends strongly on important interactions between OH and HO2 radicals with CO and NO, respectively, which affect the ratio n(OH)/n(HO2) at the tropopause level; between OH and NO2, which lead to the formation of nitric acid with its downward transport toward the troposphere; between NO and HO2, which lead to NO2 and its subsequent photodissociation; between ClO and NO, which also lead to NO2 and become more important than the reaction of ClO with O; and between Cl and various molecules, such as CH4 and H2, which lead to HCl with its downward transport toward the troposphere. All these chemical processes are subject to many changes since they occur in the lower stratosphere where seasonal, latitudinal, and even day-to-day variations of the ozone concentrations are observed in association with advective and dynamic transports, which depend on meteorological conditions as indicated by variations of tropopause heights.

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Stratospheric Ozone: An Introduction to Its Study

The logical fundamentals of the theory of climate are outlined: (1) the climate system OLA (ocean–land–atmosphere) is defined; (2) analogously to the theory of turbulence, the notion of climate is defined as a multicomponent random function in the OLA space-time (or, equivalently, as a statistical ensemble of states the OLA system passes through in a period of several decades); (3) the solar climate, i.e. the distribution of solar radiation at the upper atmosphere boundary, is determined, to be employed as the boundary condition for the OLA system; (4) the 'horizontal' heat and mass transfer processes between the equatorial and polar zones are described; (5) the 'vertical' processes of radiative–convective heat and mass transfer, among them the greenhouse effect of water vapor and small gas admixtures, are discussed; (6) the 'vertical' radiative heat transfer processes in an aerosol-containing atmosphere is considered, including the anti-greenhouse effect of volcanic and smoke aerosols, and the 'nuclear night' and 'nuclear winter' scenarios.

Climate as a problem of physics

Possible existence and role of excited ozone precursors in the stratosphere

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5. Stratospheric Ozone: An Introduction to Its Study

Some of the problems and uncertainties of stratospheric–mesospheric modeling are discussed in terms of the variables which constitute the continuity equation. The status of one- and two-dimensional eddy coefficients, required in the evaluation of the flux equation, are briefly reviewed. The production and loss terms are discussed both generally and with respect to the particular uncertainties in the CH4, H2O–HOx, NOx, and O3 chemistries.

J. C. McConnell

Papers

Uncertainties in Stratospheric–Mesospheric Modeling