Extended Abstract (136K)P2.9
Impact of the cloud spatial distribution on solar UV radiation transfer
Didier Gillotay, Belgian Institute for Space Aeronomy, Brussels, Belgium; and T. Besnard and I. Labaye
Due to their effects on public health and to their potential increase linked to stratospheric ozone depletion mainly in the mid-latitude areas, solar UV radiations are intensively studied and monitored since more than ten years. Most studies show a good agreement between measurements and model-predicted values in clear sky or homogeneous cloud cover conditions. However in �broken clouds� situations the problem is largely more complex and the systematic disagreement between measurements and models appears.
We will show that it is possible to reproduce �real case measurements� by calculating, by means of a radiation transfer model, the total irradiance as the integral of elementary radiances on 2psr; each of the radiances being �corrected� for clouds effects by introducing neutral filters (assumed to represent clouds) positioned at various altitude. Sensitivity studies will also illustrate the impact of the �neutral filter� properties, optical density, positions, apparent surface� In addition to the other atmospheric properties, ozone, aerosols�, the importance of a realistic description of real cloud conditions is shown to be indispensable to obtain a correct agreement between experimental measurements and theoretical calculations.
Poster Session 2, Cloud Physics Poster Session II
Tuesday, 4 June 2002, 1:00 PM-4:00 PM
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