Coherens model results

Before releasing the program to a more extended user group a series of test simulations is performed and intercompared by the partners using a broad range of computing platforms. The aim of this exercise is to:

• test the portability of the COHERENS code
• verify the model results against exact or approximate analytical solutions (test cases cones, front, seich and pycno) or to validate the model against measured data (test case csnsp)
• show how model results are affected by different choices of model switches and parameters
• illustrate how model applications are set up
• present an overview of the different processes which can be simulated with COHERENS

A series of idealised test cases has been developed for this study. Their source code and input data are available on the CD-ROM. The first intention is to compare the performance of the different numerical schemes for the advection of currents and scalars, and the different turbulence closure schemes, which are implemented in the program. Secondly, they show the ability of the model to simulate the strong density fronts in coastal areas, including river plume salinity fronts and thermal fronts, and seasonal thermal stratification in shelf seas. One test case illustrates the performance of the biological and sediment components of the program. Simplified initial and forcing conditions are considered in each test case allowing a clear interpretation of the results.

Test case nspbio

 
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The test case nspbio simulates the seasonal cycle of temperature and of microbiological and resuspension processes at 55°30'N, 0°55'E in the central part of the North Sea. The figures are depth-time contour plots of chlorophyll and sediment concentration. The spring bloom is clearly observed. Resuspension into the surface layer is inhibited during the summer due to the thermocline located at a depth of 20m. An autumn bloom occurs after erosion of the thermocline