Optical properties of Black Sea case 2 waters
Capet, A.; Beckers, J.-M.; Grégoire, M. (2012). Optical properties of Black Sea case 2 waters, in: 44th international Liège colloquium on ocean dynamics "Remote sensing of colour, temperature and salinity – new challenges and opportunities" - May 7-11, 2012. pp. 1 In: (2012). 44th international Liège colloquium on ocean dynamics "Remote sensing of colour, temperature and salinity – new challenges and opportunities" - May 7-11, 2012. GHER, Université de Liège: Liège. 126 pp., more |
| Abstract | Ocean color observation by satellite provide the data needed to quantify optically active constituents of sea water (living algae, particulate organic/mineral material, colored dissolved matter) but the general empiric algorithms used to derive these quantities are usually poorly adapted to specific coastal water in which the different components does not covariate, as it is the case in the Black Sea, and particularly on the North Western Shelf (NWS).In order to provide additional material to understand the imperfections of the satellite algorithms and to study the dynamics of optically active material in the BS-NWS, we address the penetration of light in the Black Sea by setting up a specific optional model included in the 3D biogeochemical GHER model.While relying on state-of-the art literature [Neukermans, 2012; Stramsky, 2007; Vaillancourt, 2004] for the parameterization of absorption and backscattering by the modeled phytoplankton and particulate matter components, the set-up also makes use of in-situ photosynthetically active radiation (PAR) profiles to assess the effect of unrepresented and optically relevant water constituent, such as the colored dissolved matter.By computing absorption and backscattering coefficients to derive diffuse attenuation, the model allows derivation of diffuse attenuation coefficients, more easily comparable with satellite measured quantities. In this way, the effectiveness of case II specific algorithms used to derive concentrations from satellite products can be directly assessed for this region.In-situ chlorophyll measurements then comes as a third-party additional point of view, completing by triangulation the comparison of model results and satellite observations (Seawifs) and the study of the Black Sea NWS photosynthesis dynamics.The importance of light penetration scheme in the biogeochemical model is finally illustrated by evidencing its impact on the resolution of bottom oxygen concentration, which constitutes a major issue of the Black Sea NWS environmental status [Mamaev, 1997]. |
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