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A compiled set of in situ data is important to evaluate the quality of ocean-colour satellite-data records. Here we describe the data compiled for the validation of the ocean-colour products from the ESA Ocean Colour Climate Change Initiative (OC-CCI). The data were acquired from several sources (MOBY, BOUSSOLE, AERONET-OC, SeaBASS, NOMAD, MERMAID, AMT, ICES, HOT, GeP&CO), span between 1997 and 2012, and have a global distribution. Observations of the following variables were compiled: spectral remote-sensing reflectances, concentrations of chlorophyll a, spectral inherent optical properties and spectral diffuse attenuation coefficients. The data were from multi-project archives acquired via the open internet services or from individual projects, acquired directly from data providers. Methodologies were implemented for homogenisation, quality control and merging of all data. No changes were made to the original data, other than averaging of observations that were close in time and space, elimination of some points after quality control and conversion to a standard format. The final result is a merged table designed for validation of satellite-derived ocean-colour products and available in text format. Metadata of each in situ measurement (original source, cruise or experiment, principal investigator) were preserved throughout the work and made available in the final table. Using all the data in a validation exercise increases the number of matchups and enhances the representativeness of different marine regimes. By making available the metadata, it is also possible to analyse each set of data separately. The compiled data are available at doi:10.1594/PANGAEA.854832 (Valente et al., 2015).

A model of particle absorption coefficients is presented as a function of chlorophyll concentration. The model has been derived from remote sensing reflectance and chlorophyll concentration of CalCOFI bio-optical data set, using a radiance model. Variance in absorption coefficient for a given chlorophyll concentration can be reduced by introducing sitedependent particle backscattering coefficients, average of which is assumed to follow Morel's backscattering model. With an empirical algorithm for estimating the absorption by dissolved organic matter, we separate the absorption by particles from the total absorption. Through a simple quality control, statistical regression gives the parameterization of particle absorption. By applying the derived model to a semi-analytical inversion algorithm, we demonstrate the proposed model could be used to retrieve in-water parameters such as chlorophyll concentration, absorption by colored dissolved organic matter and particle backscattering coefficients.

Eddies along the Polar Front/Marginal Ice Zone (MIZ) in Fram Strait are thought to make important contributions to nutrient flux and stimulation of primary productivity. During the Coordinated Eastern Arctic Regional Experiment (CEAREX) helicopter-based measurements of upwelling radiance were made in four visible spectral bands and in the thermal IR across mesoscale features associated with the MIZ. These structures were mapped by flying a grid pattern over the ocean surface to define eddy boundaries. Subsequently, the area was also sampled vertically with CTD and spectral radiometer profilers. Data obtained from a single structure were integrated to construct a three dimensional picture of physical and optical properties. Volume modeling of temperature, salinity, and density fields obtained from CTD survey define the subsurface eddy structure and are in good agreement with infrared derived characteristics. Maximum temperature in the core was found to be four degrees higher than the surrounding water. Volume modeling further indicates that a subsurface layer of Arctic Intermediate Water is intrinsically associated with the surface expression of the eddy. The ratio of upwelling radiances, L(44l)/L(565), was found to be correlated to surface chlorophyll, particulate absorption coefficient, and in water determinations of L using the optical profiling system. The remote sensing reflectance ratio along with the IR sea surface temperature were found to be useful to detect the surface expression of the eddy and to indicate near surface biological and physical processes.

Particulates in aquatic environments dominate variability in inherent and apparent optical properties. Dilute concentrations have made the quantitative determination of particulate absorption a relatively difficult problem. A quantitative filter technique (QFT) has been described previously1 ,2 which allows determination of the particulate absorption coefficient (a(A)) for samples concentrated on filters by correcting for the pathlength amplification effect (,8). DetaiI of the generality, accuracy and precision of the procedure have not been reported previously. A spectrophotometer equipped with an integrating sphere accessory was used to study the optical density of phytoplankton suspensions and colored polystyrene beads, OD(A), and the optical density of the same suspensions on a variety of common filter types, OD(A). The ratio of OD(A)/OD5(A) confirms that multiple scattering in filters leads to variable 6, a non-linear function of OD.(A). Studies of OD(A) when the filters are mounted in different positions in a single spectrophotometer, and for standard and integrating sphere spectophotometers indicate that the procedures presented are of general applicability. With proper care in baseline correction and sample preparation, spectra of a(A) can be calculated from measurements of OD\) for aquatic particles of diverse size and refractive index with an accuracy of better than i A comparison of filter types commonly used for aquatic research indicates that different algorithms are required for estimation of a(A) from OD(A) measurements using different filter types.