e. 445, 490, 555, 645 and 665 nm). Regardless of this evident limitation, it seems to be a significant and meaningful result that the formulas found here to be the most effective clearly demonstrate a potential for retrieving information on suspended matter in the Baltic Sea using the red part of the remote-sensing reflectance spectrum. This particular result is in agreement with the conclusion reported much earlier by Siegel and his collaborators (see e.g. Siegel et
al. (1994) and the list of works cited there). Those authors showed that for the case of the Baltic Sea one could achieve a distinct improvement in the accuracy of remote sensing algorithms for estimating suspended matter, chlorophyll, and click here also yellow substance and euphotic depth, with the use of red wavelengths in the reflectance ratios. They proposed various algorithms for the different satellite instruments of that time (i.e. for CZCS, SeaWiFS and (planned at that time) the MERIS instrument) using, among others, the 670 and 710 nm bands in the red part of the light spectrum.
Nevertheless, the possibility of using red band reflectance has also been reported for different coastal environments, especially for determining the suspended matter mass concentration. For Y-27632 in vivo example, Ahn et al. (2001) suggested using reflectance values in the 625 nm band as optimal for SPM concentration retrieval in coastal regions of the Korean peninsula (the equation they suggested was SPM = 647.8(Rrs(625))0.86). The possibility of estimating SPM using Band 1 of the MODIS sensor was also discussed Casein kinase 1 in a few other papers (we recall that MODIS Band 1 is a relatively broad spectral band (620–670 nm), with a nominal centre wavelength of 645 nm, originally not designed for ocean colour applications but rather for detecting land/cloud/aerosols boundaries, and providing data with a spatial resolution of up to 250 m, see e.g. the documentation available at http://oceancolor.gsfc.nasa.gov). Linear relationships for SPM as functions of values obtained
for that band were given by Miller & McKee (2004) for data from selected coastal environments of the Gulf of Mexico, by Rodriguez-Guzman & Gilbes-Santaella (2009) for a tropical open bay in western Puerto Rico, and by Wang et al. (2012) for the Bohai Sea of China. In another work, Wong et al. (2007) pointed out the possibility of using different combinations of MODIS sensor bands (among which there was also a Band 1) for data from coastal regions of Hong Kong. But in case of the Baltic Sea data analysed here, the formula (9) using a blue-to-red ratio (Rrs(490)/Rrs(645)) seems to be more effective than formula (8), which is based on the absolute reflectance value in the red band (Rrs(645)).
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