The North Sea is part of the north-west European Shelf of the North Atlantic. The circulation is counter clockwise and shows a strong dependency on the open boundaries. Nutrient inputs from the Atlantic, the rivers, the sediments and the Wadden Sea causes areas of high productivity. Observations show low production zones in the stratified regions and higher production in the well-mixed areas. Although there were big observational programms (Charnock et al., 1994; Sündermann 1994), the capacity of ship and man power is not enough to study the different regional primary production cycles. One way out is the use of a numerical model if all the necessary forcing is available. The "Ecological North Sea Model, Hamburg, Version 1 (ECOHAM1)" is such a model.

ECOHAM1 was developed in the frame of the German project KUSTOS (1994 - 1997) in the IfM working group ECOLOGICAL MODELLING. The focus was to merge a water column model of the phytoplankton-phosphate dynamics (Radach and Moll, 1993) with a transport model (Pohlmann, 1991) into a three-dimensional primary production model for the North Sea (Moll, 1995). The aim was to use the model as a tool to quantify the regional productivity on an annual basis.

• CHARNOCK, H., Dyer, K.R., Huthnance, J.M., Liss, P.S., Simpson, J.H. und Tett, P.B. (Eds.). (1994):
  Understanding the North Sea System. London: Chapman & Hall. 222pp.
• MOLL, A. (1995):
  Regionale Differenzierung der Primärproduktion in der Nordsee: Untersuchung mit einem drei-dimensionalen Modell. Berichte aus dem Zentrum für Meeres- und Klimaforschung; Reihe B: Ozeanographie, 19, 151pp.
• PÄTSCH, J. (1994):
  MOCADOB a Model Generating Synthetical Time Series of Solar Radiation for the North Sea. Berichte aus dem Zentrum für Meeres- und Klimaforschung; Reihe B: Ozeanographie, 16, 67pp.
• POHLMANN, T. (1991):
  Untersuchung hydro- und thermodynamischer Prozesse in der Nordsee mit einem dreidimensionalen numerischen Modell. Berichte aus dem Zentrum für Meeres- und Klimaforschung, 23, 116pp.
• RADACH, G. and MOLL, A. (1993):
  Estimation of the variability of production by simulating annual cycles of phytoplankton in the central North Sea. Prog. Oceanogr., 31, 339-419.
• SÜNDERMANN, J. (Ed.). (1994):
  Circulation and Contaminant Fluxes in the North Sea. Berlin: Springer-Verlag. 654pp.