1. General Model Information

Name: ECOHAM1 Ecological North Sea Model Hamburg

Acronym: ECOHAM1


Main medium: aquatic
Main subject: population dynamics, biogeochemistry
Organization level:
Type of model:
Main application:
Keywords: North Sea, primary production, plankton dynamics, phosphorus budget, German Bight, drift experiment,

Contact:

Dr. Andreas Moll
Institut für Meereskunde
Universität Hamburg
Troplowitzstr. 7
D-22529 Hamburg
Germany

Phone: +49 (0)40 4123 2526
Fax: +49 (0)40 560 57 24
email: moll@ifm.uni-hamburg.de
Homepage: http://www.ifm.uni-hamburg.de/~moll/index.html

Author(s):

Dr. Andreas Moll

Abstract:

Source of abstract: http://www.ifm.uni-hamburg.de/~moll/ECOHAM1/ecoham1.html

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. It was developed in the frame of the German project KUSTOS in the working group ECOLOGICAL MODELLING as the PhD thesis of Dr. A. Moll. The focus of my dissertation 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. Primary production is limited in the model by solar radiation, the triggering nutrient phosphate and zooplankton grazing due to prescribed monthly mean copepod biomass. The horizontal grid size of the numerical model is 20x20 square kilometer, the vertical resolution is 5 m for the upper 50 m and increasing layer thickness below 50 m up to maximal 19 layers.

The forcing for the model is as close as possible for an actual year (1985-1994), to include the physical short term variability, that determines the phytoplankton system. The probably most prominent feature of the North Sea dynamics for annual studies is the residual circulation (integration over the tidal cycle). A three-dimensional baroclinic circulation model (Pohlmann 1996) provided the daily mean velocities and eddy diffusivities that were used to advect and diffuse the compontens of the biological model. Phosphate regeneration occured in the pelagic and through a simple parameterization at the bottom via a benthic detritus pool. Solar radiation was calculated every 30 minutes for each grid point by an octa-model using daily cloud data (Pätsch 1994). The under water light is modified by self-shading.

The three-dimensional model ECOHAM1 is the simplest model for the analysis of the phytoplankton dynamics, the phosphorus transports, and the primary productivity in the North Sea. The model based on a simple phosphorus cycle, took only two pelagic variables as phytoplankton and phosphate into account, used the simplest parameterization for pelagic and benthic regeneration, and prescribed the copepod biomass for the trophic edge of zooplankton. The model impresses by the results despite its simplicity. A full description of the simulation of 1986 is given in Moll (1995,1997) and a model animation is available in the World Wide Web under http://ifmaix7.ifm.uni-hamburg.de/kino.html, described by Luff et al. (1996).


II. Technical Information

II.1 Executables:

Operating System(s):

II.2 Source-code:

Programming Language(s):

II.3 Manuals:

The implementation and running of the model is described by Moll (1997) as an User Guide to ECOHAM1

II.4 Data:



III. Mathematical Information


III.1 Mathematics


III.2 Quantities


III.2.1 Input

III.2.2 Output


IV. References

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.
LUFF, R., MOLL, A. & POHLMANN, T. 1997. Animation of three-dimensional model results of the North Sea. EOS, 77, 529.
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.
MOLL, A. 1996. ECOHAM - User Guide. Technical Reports of the Institut für Meereskunde Hamburg, 39pp.
MOLL, A. 1997. Modelling primary production in the North Sea. Oceanography, 10(1), 24-26.
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.
POHLMANN, T. 1996: Calculating the annual cycle of the vertical eddy viscosity in the North Sea with a three-dimensional baroclinic shelf sea circulation model. Continent. Shelf Res., 16, 147-161.
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.
MOLL, A. (1998): Regional distribution of primary production in the North Sea simulated by a three-dimensional model, J. Mar. Syst., Vol. 16(1-2).
MOLL, A. (1997): Phosphate and plankton dynamics during a drift experiment in the German Bight: simulation of phosphorus-related plankton production, Mar. Ecol.-Prog. Ser., Vol. 156.
MOLL, A. (1995): Regional Distribution of Primary Production in the North Sea Simulated by a Three-Dimensional Model, PhD Thesis, in the DIALOG II Program.


V. Further information in the World-Wide-Web

Homepage of Andreas Moll at IFM HH: http://www.ifm.uni-hamburg.de/~moll/index.html

VI. Additional remarks


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last modified by Tobias Gabele Wed Aug 21 21:44:42 CEST 2002

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