Distribution and flux of suspended matter in the Wadden Sea investigated with optical in situ and remote sensing methods

Nina Gemein, Thomas Badewien, Andrea Lübben, Rainer Reuter
Carl von Ossietzky Universität Oldenburg, Institute of Physics, D-26111 Oldenburg, Germany
nina.gemein@uni-oldenburg.de

Olaf Dellwig, Hans-Jürgen Brumsack
Carl von Ossietzky Universität Oldenburg, Microbiogeochemistry ICBM, D-26111 Oldenburg, Germany

ABSTRACT

The Wadden Sea is a highly dynamic tidal flat system in the south-eastern North Sea influenced by open marine and on-shore processes. Physical, biological and geo-chemical conditions in the water column differ with tide, day and season. One of the goals of our Wadden Sea Research project is to characterise and quantify the main water constituents in the tidal flats, and to investigate the processes, which control the flux of dissolved and particulate matter between the open sea and the back barrier tidal flats.

Besides seawater analysis with CTD measurements and water sampling and filtration we use optical methods to gain specific information on suspended matter:

• multispectral transmissometry, where an inverse model retrieves the amount of suspended mineral particles also in the presence of gelbstoff and phytoplankton,
• multispectral radiometry of the reflected daylight.
• level 2 satellite images from the imaging spectrometer MERIS on ENVISAT.

Suspended matter data from filtration are used to verify the transmissometer data. Furthermore, filtration data are used to examine algorithms based on multispectral radiometry with the goal to derive suspended matter concentrations from daylight reflectance spectra. Finally, these results serve to investigate the quality of TSM data in MERIS images of the Wadden Sea with TSM concentrations up to 72 mg/l, which is the validity range of the presently used MERIS algorithms.

Last Update: 2005-03-16