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DLR-P5: MERIS Application and Regional Products Project МАРР 
Objectives 
development of algorithms to generate regional products (concentration of suspended 
particulate matter, phytoplankton and pigment, and yellow substances in coastal and inland 
bodies of water) from the data of MERIS imaging spectrometer flown on the ESA satellite 
ENYISAT (launched in 1999) 
validation of MERIS products 
supporting users of MERIS data products 
Present scientific knowledge 
In the optical spectrum of visible and near-infrared light (VIS/NIR) from 400 nm to about 
1000 nm wave length, it is possible to measure the spectral characteristics of sunlight scattered 
from the water body and draw conclusions as to the type and concentration of substances in 
the water. 
The evaluation is relatively simple if only the concentration of a particular substance changes. 
In remote sensing of phytoplankton concentrations in offshore areas of the ocean, it is 
assumed that only this concentration changes. Assuming that the specific optical properties of 
phytoplankton are constant, it is possible to determine its concentration from the ratio of two 
radiance values in the blue-green part of the spectrum or from the natural fluorescence of 
plankton. 
In coastal waters where the reflection spectrum is changed by several waterborne substances 
(phytoplankton, suspended particulates, yellow substances) having different optical properties, 
an evaluation by colour ratios is not normally possible, even if the data have been obtained by 
measurements with a high spectral resolution. Their concentrations can only be determined by 
inverse radiative transfer modelling. 
The optical properties of water-borne substances in coastal waters are temporally and spatially 
variable due to, e.g., different species composition of the phytoplankton. This necessitates use 
of regionally adjusted methods in coastal waters. 
The MERIS data, with a large number of narrow-band channels, coupled to medium-size 
bottom pixels, open up novel applications, especially in the coastal zone, facilitating the 
development of advanced correction and interpretation methods, in particular: 
- improved methods for atmospheric correction 
- improved inversion algorithms for the determination of chlorophyll-a and other pigments by 
using several spectral channels and evaluating the natural fluorescence of chlorophyll-a at 
685 nm 
- algorithms enabling different pigments (separation of algae species) to be distinguished. 
Waterborne substances are also computed by ESA from the MERIS data but it uses a global 
algorithm with constant IOPs. In preliminary studies, users at monitoring authorities and 
research facilities, inter alia, were of the opinion that the accuracy of those algorithms was not 
sufficient for their purposes. The accuracy will be increased by improving the evaluation 
algorithms and, particularly, introducing regional and possibly seasonal IOPs. 
Observation and investigation methods 
In future satellite missions for remote sensing of the biosphere (land/water) and atmosphere, 
imaging spectrometers will be increasingly used. ESA is developing the Medium Resolution