CoastColour Round Robin data sets: a database to evaluate the performance of algorithms for the retrieval of water quality parameters in coastal waters

摘要

The use of in situ measurements is essential in the validation and evaluation ofthe algorithms that provide coastal water quality data products from oceancolour satellite remote sensing. Over the past decade, various types ofocean colour algorithms have been developed to deal with the opticalcomplexity of coastal waters. Yet there is a lack of a comprehensiveintercomparison due to the availability of quality checked in situ databases. TheCoastColour Round Robin (CCRR) project, funded by the European Space Agency(ESA), was designed to bring together three reference data sets using these totest algorithms and to assess their accuracy for retrieving water qualityparameters. This paper provides a detailed description of these referencedata sets, which include the Medium ResolutionImaging Spectrometer (MERIS) level 2 match-ups, in situ reflectancemeasurements, and synthetic data generated by a radiative transfer model (HydroLight).These data sets, representing mainly coastal waters, are available from href="http://dx.doi.org/10.1594/PANGAEA.841950">doi:10.1594/PANGAEA.841950.The data sets mainly consist of 6484 marine reflectance (eithermultispectral or hyperspectral) associated with various geometrical (sensorviewing and solar angles) and sky conditions and water constituents: totalsuspended matter (TSM) and chlorophyll a (CHL) concentrations, and theabsorption of coloured dissolved organic matter (CDOM). Inherent opticalproperties are also provided in the simulated data sets (5000 simulations)and from 3054 match-up locations. The distributions of reflectance atselected MERIS bands and band ratios, CHL and TSM as a function ofreflectance, from the three data sets are compared. Match-up and in situ sites wheredeviations occur are identified. The distributions of the three reflectancedata sets are also compared to the simulated and in situ reflectances usedpreviously by the International Ocean Colour Coordinating Group (IOCCG,2006) for algorithm testing, showing a clear extension of the CCRR datawhich covers more turbid waters.