e. the backscattering and absorption coefficients of light by seawater at certain light wavelengths). In the second approach, theoretical radiative transfer modelling was additionally incorporated, which enabled the existing empirical dataset to be supplemented with modelled spectra of remote-sensing reflectance. Based on the extended dataset, including both empirical and modelling

results, another set of statistical formulas, of a semi-empirical nature, were then found. This enabled the biogeochemical properties of suspended particulate matter to be estimated directly from remote-sensing reflectance values at certain light wavelengths or from reflectance ratios. The IDH inhibitor methodological details of these procedures are given below. The empirical dataset on the biogeochemical properties and IOPs of surface seawater available for the purpose of the current work is mostly a selection from the results of field measurements and laboratory analyses of discrete water samples already

described in an earlier work (S. B. Woźniak et al. 2011). In the current work, therefore, where appropriate, the empirical methods used are described only briefly; the interested reader will find comprehensive information on the subject in that earlier paper. The empirical data utilised in this work were gathered at 294 sampling stations during 16 short cruises on board r/v ‘Oceania’ between August 2006 and September 2009. selleck inhibitor The study area covered the open waters of the southern Baltic Sea as well as the coastal regions of the Gulf of Gdańsk and the Szczecin Lagoon (the area located roughly between 12°38′E and 19°30′E, and 53°42′N and 55°38′N, see Figure 2). At each station the seawater IOPs were measured in situ in the surface layer of seawater (in practice, depending on the sea state, the depth of this layer varied between 1 to 1.5 m), and water samples Thiamet G from that layer were also collected with 20 L Niskin bottles for the laboratory analysis of different biogeochemical properties of suspended matter. The Secchi depth at the sampling

stations varied from 1 m to 12 m. The biogeochemical properties of suspended matter in the surface water samples were characterised in terms of suspended particulate matter concentration (SPM) [g m− 3] using a standard gravimetric technique, the particulate organic matter concentration (POM) [g m− 3] using the loss on ignition technique, the particulate organic carbon concentration (POC) [g m− 3] using a high temperature combustion technique, and the total concentration of chlorophyll a (Chl a) [mg m− 3] (defined as the sum of chlorophyll a, allomer and epimer, chlorophyllide a and phaeophytin a) with aid of high performance liquid chromatography (HPLC) (as already mentioned, for more methodological details, see an earlier work by S.B. Woźniak et al. (2011)).