Based on the analysis of long-term measurements by bio-argo floats, characteristic features are described and quantitative characteristics of the distribution of the light backscattering coefficient by suspended particles in the upper 1000-meter layer of the Black Sea are obtained.
Based on the analysis of the Bio-Argo floats measurements for the backscattering coefficients by particles at 532 nm and 700 nm in the Black Sea waters and a regional ocean color product with the involvement of a physical model, the measurements of these parameters were corrected, the slope of the backscattering coefficients by particles was calculated, and its time function in the photic layer of the Black Sea was plotted.
Vertical diffuse attenuation coefficient, Kd(490), is one of the key parameter required for water quality modeling, hydrodynamic and biological processes in the sea. We showed that standard level-2 product of Kd(490) was underestimated in comparison with Kd(490) values simulated by the regional model during the diatom bloom in the Black Sea. Using data of SeaWiFS, MERIS and MODIS color scanners, a regional relationship between the model value of Kd(490) and the ratio of remote sensing reflectances has been obtained. Based on the bulgarian argo-bio-buoy dataset, the relationship between the attenuation coefficient of photosynthetically active radiation and attenuation coefficient at a wavelength of 490 nm is obtained. The simplified model, below as the S-model, of the diffuse attenuation coefficient spectrum for downwelling irradiance in the Black Sea upper layer is described. As a consequence of the S-model, the link between the depth of the euphotic zone and Kd(490) has been obtained. It is shown that the Kd(490) values, retrieved from ocean color data with using the regional link and from argo-bio-buoy measurements at depths between 6-20 m, are close to each other.
In this study, a regional algorithm for retrieving Inherent Optical Properties (IOPs) has been developed for the Black Sea using remote sensing reflectance at five wavelengths in the visible spectral range corresponding to the Sea-viewing Wide Field of View Sensor (SeaWiFS). The model retrieves a spectral signature of particle backscattering coefficient at 555 nm, bbp(λ), and its spectral slope, np, total absorption coefficient of colored detrital matter (sum of colored dissolved matter and non-algal particles, CDM) at 490 nm, aCDM(λ), spectral slope of CDM absorption coefficient, S, and chlorophyll a concentration, Ca. These satellite derived set of IOPs and bio-optical properties measured in situ in the western open Black Sea within period 1998-1999 have been analyzed. The result reveals four specific cases corresponding to 1) variation of spectral slope of CDM absorption coefficient, 2) coccolithophores blooms, 3) domination of micro-celled phytoplankton (diatoms and/or dinoflagellates) and 4) presences of the picoplankton in phytoplankton community. Examples of the spatial distribution and seasonal variability of the retrieved parameters in half-monthly composite maps are presented. A complete set of these maps for SeaWiFS lifetime is available on http://blackseacolor.com/.
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