Modelling Oxygen Depletion in Danish Waters
- assimilating interpolated 3D fields of oxygen, salinity and temperatures
The year 2002 resulted in the most severe incidence of oxygen depletion ever observed within Danish waters. This incidence was followed on-line with DHI's numerical 3D forecasting system The Waterforecast. The Danish National Environmental Institute (NERI) followed the incidence as well. NERIs approach was based on 3D interpolation of measured profiles of oxygen. With the purpose of combining the advantages of the two approaches a project called OPTIM has been set-up.
DHI's numerical biochemical model, called the EU model, developed at DHI through decades, has been applied in combination with DHI's hydrodynamic model, MIKE 3 HD, and has been included in The Waterforecast. The biochemical model includes mathematical descriptions of the governing processes influencing the oxygen concentrations, and hence potential oxygen depletion.
At the same time NERI receives information on oxygen depletion as well as measurements of oxygen carried out by the Danish Counties, the Environmental vessel, Gunnar Thorsen, and Swedish and German partners. These point measurements are interpolated to a 3D field (applying the Kriging technique).
The Waterforecast has a high degree of spatial information and a high resolution in time with data available on an hourly basis. However, The Waterforecast is not updated with measurements. On the other hand, the 3D field are based on measurements (using the Kriging technique), but are only available on a monthly basis.
During the OPTIM project, NERI will provide 3D interpolated fields of oxygen (and may also provide temperature and salinity) after each measurement campaign carried out by NERI in corporation with the Danish Counties. Subsequently, DHI will update the oxygen forecasts which will strengthen the results from The Waterforecast and give more reliable forecasts. The updates will be carried out at the end of August, September, October and November. An example of the first update is shown in the figures, where the figure above show oxygen concentrations before the update, while the figure to the right show oxygen concentrations after the update. All oxygen concentrations are at the seabed.
Information from NERI on oxygen depletion including the forecast is available at http://iltsvind.dmu.dk (only in Danish), while the forecast only is also available at The Waterforecast on http://www.waterforecast.com/iltsvind/iltsvind.asp .
For more information contact: Anders Christian Erichsen (aer@dhi.dk or +45 45 16 92 00)