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Brockmann
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Environmental Informatics • Geo -Information products
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THE WADDEN SEA IN ONE PERSPECTIVE
- MOSAICING SATELLITE IMAGES In contract with the Common Wadden Sea Secretariat (CWSS) a satellite mosaic was produced
showing the whole Wadden Sea ranging from Denmark over Germany to The Netherlands. The aim
was to display the tidal flats of the Wadden Sea at once . This is not a realistic view, because the tidal
wave moves from north to south radially along the coast and covers always parts of the intertidal
flats. This mosaic enables the one-off chance to look at the total area of the trilateral Wadden Sea.
But not only this view is fascinating. Beside this, the sediment transport into the North Sea can be
detected very well. The suspended matter is transported from the rivers and the tidal flats along the
coast and into the North Sea. The northern part of the mosaic, west of Blåvands Huk and Fanø a huge
algal bloom can be seen. Or regarding the embankment of the Lake IJssel, different water bodies
show different structure and colour depending on different water constituents.
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THE WADDEN SEA IN ONE PERSPECTIVE
Such an image can only be produced by combining different satellite images from different acquisition
dates. The satellite system was the Landsat 7 ETM, which has a spatial resolution of 30 x 30 m. This
means that each pixel of the image represents an area of 30 x 30 m at the surface. Landsat detects
the surface of the earth with 7 bands, sensible for different wavelength ranges of the spectrum of
light. In order to produce an image wit h realistic colours, the 3 bands detecting the visible light (red green - blue) are combined to an RGB image. The satellite images had to be chosen in that way that
the cloud conditions and tidal stage allow the view on the land, tidal flats and the North Sea. This
reduced the potential images very much, so that the images date from 3 different years and from
different seasons. This causes phenological differences and therefore differences in the colours of the
images. The 5 images which were acquired in April 2003, Mai 2000 and 2001 and Juli 2002 had to be
adjusted geographically and colour wise. The spatial extension of the Mosaic come to ca. 340 km in
from North to South and ca. 460 km from West to East.
Original Data
© Landsat 7 ETM
2000-2003 Eurimage
Brockmann
Consult
Environmental Informatics • Geo -Information Products
Contact Person
Kerstin Stelzer
Geographer
[email protected]
Telefon:+49 (0) 4152-889-307