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Ionospheric evidence is presented to show that oxygen at ionospheric heights is dissociated much more in the winter hemisphere than in the summer. The pattern of atmospheric composition is interpreted by a model based on three factors: the dissociation of oxygen, horizontal transport by meridional flow in the upper atmosphere, and vertical transport by diffusion. The second factor introduces large scale meteorology as a major influence in the ionosphere.
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G.A.M. King (1964) studied this question.
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