© 1998 by ICES/CIEM International Council for the Exploration of the Sea/Conseil International pour l'Exploration de la Mer
Data needs for ecosystem modelling
Ecological Modelling Centre, Joint Department of VKI and DHI Agern Allé 5, DK-2970, Hørsholm, Denmark
Netherlands Institute for Sea Research PO Box 59, NL-1790 AB Den Burg, Texel, The Netherlands
Correspondence to J. W. Baretta: tel. +45 4517 9124, fax. +45 4517 9200, e-mail: baretta{at}dhi.dk
To test, verify, and improve marine ecosystem models there is an urgent need for time series of those variables that reflect the state of the system in terms of productivity, nutrient cycling, and oxygen dynamics. Not only time series of verification data are needed, but also time series for the forcing functions (wind, irradiance, river inflows, and nutrient loads), as well as for the boundary conditions. Especially in open systems like the North Sea, where nutrient imports across the boundaries by far exceed river inputs, the boundary conditions are of crucial importance. The existing data coverage of the open boundaries is so sketchy that inter-annual variability has to be ignored and only climatological time series can be constructed for all variables. Model results are presented to demonstrate the linkage between realistic forcing and realistic system response, indicating that coupled hydrodynamical ecosystem models can reproduce and explain the observed variability in aquatic systems when provided with forcing conditions at appropriate time scales. The paper presents arguments for measuring fluxes and rates rather than standing stocks as a means for verifying ecosystem models.
Keywords: coupled hydrodynamical/ecological models, ecosystem modelling, long-term time series, mathematical models, model verification, nutrient dynamics simulation models