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A hydrographic time series station in the Wadden Sea (southern North Sea)
Rainer Reuter, Thomas H. Badewien, Alexander Bartholomä, Axel Braun, Andrea Lübben and Jürgen Rullkötter
Ocean Dynamics, Special Issue - WATT
Abstract
In the tidal inlet between the East Frisian islands of Langeoog and
Spiekeroog, southern North Sea, a time-series station was set up in autumn
2002 as part of the research programme BioGeoChemistry of Tidal Flats run
by the University of Oldenburg. The purpose of the station is to provide
continuous data on physical, biological and chemical parameters. In addition
to instruments recording basic hydrographic and meteorological parameters,
the time-series station is equipped with acoustic Doppler profilers for
measuring surface waves and current profiles. Compact optical spectrometers
are being used for spectral measurements of seawater transmission and for
daylight reflectance. Additional sensors were installed for measuring oxygen,
nutrients and methane in the seawater. The data shall help to quantify the
flux of dissolved and suspended matter between the backbarrier tidal flat and
the open sea and to characterise the material transformation in the tidal flat
area by biogeochemical processes over the tidal cycle. Due to its novel
design, operation of the station is also possible during winter and under
extreme weather conditions (gales, storm surges, and sea ice) when data
sampling with conventional platforms such as research vessels, buoys, or
smaller poles could not be performed in the past. In this way, time series of
data are obtained, which include events that are most relevant to the
evolution of this coastal area. The performance of the station and its
equipment are presented with data covering 6 years of operation. Time series
of air and water temperature as well as seawater salinity demonstrate the
multiyear dynamics of these parameters in the East Frisian Wadden Sea.
Hydrographic data collected under specific meteorological conditions such as
gales and storm surges exemplify the all-weather capabilities of the station
and its value for studying hydrographic processes in the Wadden Sea.
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