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

The use of in situ measurements is essential in the validation and evaluation of the algorithms that provide coastal water quality data products from ocean colour satellite remote sensing. Over the past decade, various types of ocean colour algorithms have been developed to deal with the optical complexity of coastal waters. Yet there is a lack of a comprehensive intercomparison due to the availability of quality checked in situ databases. The CoastColour Round Robin (CCRR) project, funded by the European Space Agency (ESA), was designed to bring together three reference data sets using these to test algorithms and to assess their accuracy for retrieving water quality parameters. This paper provides a detailed description of these reference data sets, which include the Medium Resolution Imaging Spectrometer (MERIS) level 2 match-ups, in situ reflectance measurements, and synthetic data generated by a radiative transfer model (HydroLight). These data sets, representing mainly coastal waters, are available from doi:10.1594/PANGAEA.841950. The data sets mainly consist of 6484 marine reflectance (either multispectral or hyperspectral) associated with various geometrical (sensor viewing and solar angles) and sky conditions and water constituents: total suspended matter (TSM) and chlorophyll a (CHL) concentrations, and the absorption of coloured dissolved organic matter (CDOM). Inherent optical properties are also provided in the simulated data sets (5000 simulations) and from 3054 match-up locations. The distributions of reflectance at selected MERIS bands and band ratios, CHL and TSM as a function of reflectance, from the three data sets are compared. Match-up and in situ sites where deviations occur are identified. The distributions of the three reflectance data sets are also compared to the simulated and in situ reflectances used previously by the International Ocean Colour Coordinating Group (IOCCG, 2006) for algorithm testing, showing a clear extension of the CCRR data which covers more turbid waters

Analysis of IRS-P4 OCM data for estimating the suspended sediment concentrations along the Mangalore Coast, India

Information on Suspended Sediment Concentration (SSC) in coastal waters is necessary for the understanding and management of the coastal environment. In the present study, estimation of SSC has been carried out along the Mangalore Coast, West coast of India, using both in-situ and Indian Remote sensing Satellite (IRS) – P4 Ocean Color Monitor (OCM) data. The OCM Data Analysis Software (OCMDAS) developed by Space Applications Centre (SAC), Ahmedabad, India, which is based Tassan’s algorithm was used to estimate the SSC and validated through sea-truth data collected along the Mangalore Coast. Eighty six surface water samples were collected during the post-monsoon (21.11.1999) and pre-monsoon (07.05.2000) period, near synchronized with IRS-P4-satellite overpass, and SSC was measured using 0.47µm Whatman filter papers with the help of Millipore filter assembly. Out of ninety water samples, eighty two were used to generate the SSC map of the study area and eight samples at few important locations (rivermouth with/without breakwater, man-made coastal structures, and open beaches) were selected to validate the algorithm. Measured SSC varied between 26mg/L and 48mg/L in pre-monsoon and between 16mg/L and 40mg/L during post-monsoon period. The estimated SSC varied between 11mg/L and 47mg/L in pre-monsoon and between 14mg/L and 33mg/L during post-monsoon period. The co-efficient of determination for the relationship developed between measured and estimated SSC is about 0.90 and root mean square error is 14 mg/L