Search publications of the members of the Royal Belgian institute of natural Sciences
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Variability in radiocarbon dates in Middle Pleniglacial wood from Kurtak (Central Siberia)
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Integrating field data to parameterize a larval transport model of sole and improve knowledge on recruitment in the North Sea.
- Inter-annual recruitment variability of sole (Solea solea) in the North Sea is high. Among many fish taxa, the early life stages are critical in determining recruitment. With a Lagrangian larval transport model, coupling a physical model with an Individual-Based Model (IBM), it has been shown that hydrodynamics explains part of this variability in sole (Lacroix et al. 2013). IBMs require a good knowledge of the biological processes governing larval dispersal. However, it is difficult to obtain observations of life history traits; their estimates may strongly influence larval connectivity / retention and successful migration as predicted by the model. Various assumptions about these traits can be tested by comparing simulation results with field data. Several datasets, from the literature and from a 2-year-long monthly sampling at 13 stations in the southern North Sea, will be used to identify the most plausible model parameterisation. It represents a first step towards the calibration and improvement of a larval dispersal model of sole in the North Sea and the development of a tool for fisheries management.
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Seaborne measurements of near infrared water-leaving reflectance: The similarity spectrum for turbid waters
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Atmospheric correction of SeaWiFS imagery for turbid coastal and inland waters
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A dual-nutrient-reduction strategy to control eutrophication in the southern North Sea continental waters.
- For decades the marine ecological models have sustained progressive developments and been subjected to an increasing degree of complexity in their processes, forcings and parameterization. In parallel, the validation techniques have evolved from visual to statistical comparisons, allowing fair estimates of the bias and correlations between model results and reference data. Still, it is difficult to estimate in advance what will be the uncertainty attached to any model prediction because of the complexity of the ecological models and the non linearity of their response to a change. Also, it is not trivial to determine the uncertainty of the model response due to one specific forcing, especially when this forcing is variable in time and space. The uncertainty in an ecological model response is somewhat linked to the model sensitivity to a perturbation. Since the non-linear model response to a perturbation may vary in a wide range of possibilities, we chose to base our assessment on the probability theory by applying a “light” Monte-Carlo experiment. It consists in a reduced number of randomly-perturbed simulations where knowledge of the system allows narrowing the range of perturbations. We applied the light Monte-Carlo experiment on a biogeochemical model in the English Channel and the southern North Sea (3D-MIRO&CO). The uncertainty on modelled chlorophyll a prediction was studied as a response, first, to random wind perturbations and, second, to random phytoplankton autolysis values. Statistical and probabilistic quantification of the results is being presented for the Belgian coastal and offshore zones.
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Optical teledetection of chlorophyll a in estuarine and coastal waters
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A chlorophyll-retrieval algorithm for satellite imagery (Medium Resolution Imaging Spectrometer) of inland and coastal waters
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Effect of a waveband shift on chlorophyll retrieval from MERIS imagery of inland and coastal waters
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Retrieval of oceanic constituents from ocean color using simulated annealing
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Presentation of a family of turbulence closure models for stratified shallow water flows and preliminary application to the Rhine outflow region
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Preface - 27th International Liege Colloquium on Ocean Hydrodynamics - Liege, May 8-12, 1995 - Processes in Regions of Freshwater Influence
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Model of remote-sensing reflectance including bidirectional effects for case 1 and case 2 waters
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Haline stratification in the Rhine-Meuse freshwater plume - a 3-dimensional model sensitivity analysis
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Optical remote sensing of chlorophyll a in case 2 waters by use of an adaptive two-band algorithm with optimal error properties
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Optical remote sensing in support of eutrophication monitoring in Belgian waters
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A coastal ocean model intercomparison study for a three-dimensional idealised test case
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The spectral reflectance and transparency of river plume waters
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On the signatures of river outflow fronts in radar imagery
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Development and application of an algorithm for detecting Phaeocystis globosa blooms in the Case 2 Southern North Sea waters
- While mapping algal blooms from space is now well-established, mapping undesirable algal blooms in eutrophicated coastal waters raises further challenge in detecting individual phytoplankton species. In this paper, an algorithm is developed and tested for detecting Phaeocystis globosa blooms in the Southern North Sea. For this purpose, we first measured the light absorption properties of two phytoplankton groups, P. globosa and diatoms, in laboratory-controlled experiments. The main spectral difference between both groups was observed at 467 nm due to the absorption of the pigment chlorophyll c3 only present in P. globosa, suggesting that the absorption at 467 nm can be used to detect this alga in the field. A Phaeocystis-detection algorithm is proposed to retrieve chlorophyll c3 using either total absorption or water-leaving reflectance field data. Application of this algorithm to absorption and reflectance data from Phaeocystis-dominated natural communities shows positive results. Comparison with pigment concentrations and cell counts suggests that the algorithm can flag the presence of P. globosa and provide quantitative information above a chlorophyll c3 threshold of 0.3 mg m(-3) equivalent to a P. globosa cell density of 3 x 10(6) cells L(-1). Finally, the possibility of extrapolating this information to remote sensing reflectance data in these turbid waters is evaluated.
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The COASTCOLOUR dataset
- The objective of the ESA DUE CoastColour project is to fully exploit the potential of the MERIS instrument for remote sensing of the coastal zone. The product requirements have been derived from a user consultation process. Users have provided in-situ data from many locations, which were used for algorithm development and validation. The MERIS data archive from 2005 onwards has been processed with the finally selected algorithms for 27 globally distributed coastal sites. The CoastColour dataset comprises an improved Level 1b product (L1P), a product that contains directional and normalised water leaving reflectances (L2R) and a product for water properties (L2W). The total data volume is 100TB. All data are online and available from the CoastColour Website. A near real time service was operated from October 2011 until end of the ENVISAT mission. Plans exist to continue the service with Sentinel data.
