|Dispersion of dissolved matter in the North Sea|
van Dam, G.C. (1989). Dispersion of dissolved matter in the North Sea. CM Documents - ICES, CM 1989. International Council for the Exploration of the Sea, ICES: Copenhagen. 12 + figures pp.
Part of: ICES CM Documents - ICES. ICES: Copenhagen. ISSN 1015-4744, more
A good understanding of the main physical processes responsible for the dispersion of dissolved matter in the North Sea has been obtained from the combination of measurements (currents, and distributions of natural and artificial tracers) and mathematical modelling.The mathematical models are a great help in the understanding of the results of the measurements, while the field data provide the necessary parameter values for the mathematical models. Variation of parameter values in the models gives insight in the relative importance of the various mechanisms and in the requirements for data and accuracy when the models are to be used for prediction purposes.The parameters needed for proper modelling of dispersion can be derived from measurements and simulation on relatively small scales, say up to 40 kilometers, due to the possibility of modelling water movements on larger scales in a deterministic way. The necessary smaller scale information includes the mixing rates and the velocity structure in the vertical. The latter can in principle be derived from a deterministic three-dimensional flow model or even some kind of "2-D" flow model.The influence of vertical velocity structures, as induced by friction, wind and Coriolis forces, can be investigated separately by using various analytical approximations of vertical velocity structures, without deriving these directly from 2 1/2 - or 3-D flow models. This has been done by using particle simulation techniques. The examples to be shown demonstrate the relative importance of the 3-D effects up to horizontal scales of several kilometers. From the rather large number of tracer experiments in the North Sea, a fair estimate of the spectral distribution of the energy of the horizontal water movements can be made, when taking into account the part that is taken in the total dispersion process by the effects in the vertical.