MODELING THE EFFECT OF SEA-WATER OPTICAL- PROPERTIES ON THE ULTRAVIOLET RADIANT FLUXES IN THE OCEAN

A theoretical model of solar ultraviolet (UV) radiation transfer in th e atmosphere-ocean system is developed. The model involves (a) a numer ical algorithm of radiative transfer in a stratified atmosphere-flat s ea surface-homogeneous ocean system and (b) spectral models of atmosph ere and ocean optical properties in the UV region. The model allows th e calculation of the spectral fluxes and biological doses of UV radiat ion depending on a number of parameters: the total ozone, the aerosol optical thickness, the sun's zenith angle, and the depth and optical p roperties of sea water. The model is checked integrally by correlating the calculation results with the data of onsite biodose measurements, The effect of the parameters determining the optical properties of se a water on the UV spectral fluxes and biodoses, as well as on the radi ative enhancement of the influence of ozone depletion on biodoses, is discussed Quantitative assessments of this effect are given. The key r ole of the absorption of sea-water dissolved organic matter and its sp ectral dependence in the attenuation of UV radiation in the ocean is s hown. It is found that, when estimating UV attenuation from sea-water absorption measured at a fixed wavelength, it is important to choose t his reference wavelength in the short-wavelength range of UV spectrum.