EurOCEAN 2000 - Vlaams Instituut voor de Zee

characterized by coastal aerosol and Case-2 water. A ship ensures the collection of marine
measurements. The atmospheric measurements are taken from Rame Head .
An important objective of the project is the production of a large quantity of statistically
representative, high quality oceanic and atmospheric data. To satisfy this requirement
significant efforts are put in:
• the calibration and intercalibration of instruments, to ensure the highest possible accuracy
in the conversion of measurements to geo-physical units and to make data sets from
different sites fully comparable;
• the development of processing methods for data quality assurance to avoid archival of
measurements affected by errors.
Collected data are stored at local archives at each measurement site and successively processed
and archived at a central data base.
To satisfy the requirements of the COLORS objectives, the integrated program comprises a
combination of field and laboratory measurements carried out at frequencies ensuring seasonal
characterization of sites.
The field measurements are:
(d-i) Subsurface upwelling radiance and downwelling irradiance
(d-ii) Above water downward irradiance
(d-iii) Direct sun irradiance
(d-iv) Sky radiance
(d-v) Water attenuation and absorption
(d-vi) Water temperature and salinity
(d-vii) Atmospheric pressure, humidity and temperature
(d-iii) Wind speed and direction
The laboratory measurements, providing site-specific data complementary to the field
measurements, include:
(i-i) High Pressure Liquid Chromatography (HPLC) for phytoplankton-pigments
(i-ii) In-vivo absorption spectra for pigments
(i-iii) Absorption spectra of filtered water for dissolved material
(i-iv) Gravimetric filter analysis for total suspended matter and
organic/inorganic fractions.
All the measurement sites use almost identical instruments and measurement methodologies.
This ensures the compatibility and mutual comparability of the data-sets from the different
sites.
2.2 Bio-optical and atmospheric models and algorithms for coastal/shelf areas
The accuracy of water parameters obtained from the remote sensing of ocean colour is, to a
great extent, determined by:
- the accuracy of the data used in the atmospheric correction process (i.e. the removal of
atmospheric contribution from the remotely sensed radiance);
- the accuracy of relationships between water reflectance and, particulate and dissolved matter.
Although a basic parameterisation is available, simultaneous extended in-situ marine and
atmospheric optical and bio-geo-chemical measurements have been available only rare in
European coastal areas. Using the data collected at the three sites, the project is undertaking
the development and validation of atmospheric algorithms for the parameterisation of
atmospheric optical thickness and phase function, and the development and validation of biooptical
algorithms for water particulate and dissolved matter. The ultimate goal is to develop
atmospheric and marine algorithms applicable in European waters.
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