1.4 Model Simulating the Volumetric Distribution of Elements 



The transition to three-dimensional models is a natural development 

 of the models discussed above. This transition is particularly 

 necessary upon analysis of upwelling zones or areas of the ocean with 

 strong subsurface countercurrents. Let us study the ecosystem of the 

 eastern portion of the equatorial Pacific, where we encounter a complex 

 and unique structure of the field of currents. To represent the 

 situation which has developed there as a plane model would be an 

 unjustified simplification. On the other hand, v/e do not have 

 sufficiently complete information concerning the field of currents and 

 coefficients of turbulent diffusion in this region of the ocean. 

 Therefore, we must, for now limit ourselves to a very simplified, 

 approximate plan, which is more qualitative than quantitative in nature. 



Figure 8 shows a block diagram of an elementary cell of the model 

 and the location of the cells in space. Keeping in mind the qualitative 

 nature of the model, the structure of the trophic network of a cell has 

 been greatly simplified and includes nutrient salts (n), detritus (d), 

 phytoplankton (P), bacterioplankton (b), herbivores (f), and carnivores 

 (s). 



XM f 



Fig. 8. Block diagram of 3-dimensional model of pelagic ecosystem and 

 3-dimensional placement of cells of the model. Arrows show transfer by 

 currents. In the box, we show the relationship between concentration of 

 nutrient salts (n), phytoplankton (P), bacterioplankton (d), detritus 

 (d), herbivores (f), and carnivores (s). 



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