Coastal observatories

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This article describes how fixed automated measurement stations can be used to collect hydrographic and/or meteorological data. There are several of these stations located in German coastal waters. The Coastal Observatory In Liverpool Bay UK, comprises monitoring plus operational models to provide (near) real-time information via internet. The measuring station Fino (located in the Baltic Sea) is used in this article as an example to explain the functioning of coastal observatories.

Introduction

Figure 1: Fino measuring station

A Coastal Observatory is an extensive monitoring system set up in coastal waters in order to provide comprehensive data on multiple parameters necessary to understand the important physical, chemical and biological processes taking place in the coastal waters. Data is generally measured at a high frequency (several times per day, even several times per hour), often at multiple depth levels. Most coastal observatories provide data in (near) real-time, by using telemetry to transfer measurements back to land. Coastal observatories generally have one or more fixed platforms and/or buoys with a number of instruments and sensors to measure a range of parameters such as temperature and salinity, current profiles, waves and meteorological conditions.

Additional components of a coastal observatory can include:

  • Sensors to measure turbidity, chlorophyll and nutrients;
  • Drifters, measuring surface currents and properties such as temperature and salinity;
  • Tide gauges, with sensors for meteorology, waves, temperature and salinity;
  • Shore-base HF radar measuring waves and surface currents;
  • Satellite data - infra-red (for sea surface temperature) and visible (for chlorophyll and suspended sediment);
  • Instrumented ferries (ferry boxes or ships of opportunity), including data for near surface temperature, salinity, turbidity, chlorophyll and/or nutrient values;
  • Meteorological data from local met stations;
  • Research Vessels, to service moorings and to conduct spatial surveys (in-situ data).
  • operational models which can integrate (near) real-time measurements into a (pre-)operational coastal prediction system whose results are displayed on a web site.

Fixed automated measuring stations are operational in many places of the North Sea and Baltic Sea.

German Coastal Observatories

In several areas of the German coastal area, automated hydrographic/meteorological measuring stations are operated by GKSS Research Centre (close to the island Langeoog, Jade Bay near Wilhelmshaven, Hörnum Deep south of Sylt), the University of Oldenburg (close to the island of Spiekeroog) and University of Kiel (close to Büsum). In the German Bight and the Baltic Sea, stations are operated by the Federal Maritime and Hydrographic Agency (BSH). Graphical time series are usually available on the web.

Most of these stations measure current velocity, wave height, water temperature and salinity (in several water depth levels), and meteorological parameters like air temperature and pressure, wind speed and direction and solar irradiation.

Measuring platform Fino

An example of a coastal observatory is the large measuring platform Fino (see also Figure 1). Fino is located in the Baltic Sea and is operated by BSH. It has a fairly good internet representation of time series dating back to September 2003. Graphs of current, salinity and temperature can be obtained in several depth levels down to 28 m water depth. Figure 2 shows an example of a temperature graph. These temperature measurements provide information on the stratification of the water body. In spring and summer, the warm (and sometimes fresher) surface water is separated from the colder water in the depth by permanent stratification. This breaks down in the North Sea usually in early autumn when decreasing temperatures and storms cause a better mixing of the water body.

Figure 3 shows a graph with information about salinity. Due to high river run-off and precipitation, a half-enclosed sea like the Baltic or the Black Sea are less saline than open oceans. In the Western part of the Baltic Sea, the salinity decreases from the west-side to the east-side. Along with the decrease of salinity, a higher variability of salinity is also recognized. This results from the higher inflow of (relatively) freshwater from the North Sea after severe north-western storms. This freshwater causes the regeneration of oxigen at the often anoxic bottom of the Baltic Sea. The decrease of salinity is also shown in Figure 3. The diagram in this figure shows the monthly average salinity values at five measuring stations in the Western part of the Baltic Sea.

Figure 2: Temperature measured on Fino in 2001
Figure 3: Monthly average salinity values for five stations in the western Baltic Sea


Coastal Observatory at Liverpool Bay

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The objective of the Coastal Observatory at Liverpool Bay (CoastObs) is to understand a coastal sea's response both to natural forcing and to the consequences of human activity. The Observatory integrates (near) real-time measurements with coupled models into a pre-operational coastal prediction system whose results are displayed on the CoastObs web site.

The concept is founded on obtaining data in (near) real-time, using telemetry, from underwater to the sea surface to land to POL to the web site ('armchair oceanography'). It will grow and evolve as resources and technology allow, all the while building up a long time series. The foci are the impacts of storms, variations in river discharge (especially the Mersey), seasonality, and blooms in Liverpool Bay.

Biofouling

A common problem which all these stations have to face is biofouling. The stations must be maintained on a regular basis, depending on the season, location and the type of used sensors. In the Wadden Sea, e.g., the GKSS measuring stations are cleaned every 4-5 days in summer.

See also

Internal links

External links

References


The main author of this article is Schroeder, Friedhelm
Please note that others may also have edited the contents of this article.

Citation: Schroeder, Friedhelm (2008): Coastal observatories. Available from http://www.coastalwiki.org/wiki/Coastal_observatories [accessed on 23-10-2019]