Annual variation of the effects of diffuse radiation on the photodissociation of ozone |
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| Authors: | Paolo Petroncelli Giorgio Fiocco Alberto Mugnai |
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| Institution: | (1) Università, Istituto di Fisica, Roma, Italy;(2) Laboratorio Plasma Spazio, CNR, Frascati, Italy |
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| Abstract: | Previous work has shown the importance of the diffuse solar field in the photochemistry of atmospheric active species, the solar zenith angle being an effective parameter. In view of the diurnal and seasonal variability of this single quantity, in this paper estimates are presented of the daily-integrated values of the photodissociation coefficient of ozone throughout the year, for a purely molecular atmosphere in the absence of scattering and when the effects of molecular scattering are included, and for an absorbing-scattering turbid atmosphere characterized by two different aerosol loads. Also, different values of the ground albedo have been taken into account.Results are shown for a latitude of 45oN. The seasonal dependence is strong at altitudes below 20 km and less marked above 20 km. For an albedoA=0.3, the inclusion of molecular scattering increases the daily-integrated photodissociation coefficients approximately by 20% and 40% at 15 km and by 15% and 22% at 30 km, at the winter and summer solstice respectively. The presence of a heavy aerosol load modifies these results by a further factor which is approximately –5% and 10% at 15 km at the winter and summer solstice respectively, and is approximately constant at 8% throughout the year at 30 km. |
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| Keywords: | Ozone Diffuse radiation influence |
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