ZOOPLANKTON FIELD HETEROGENEITY FORMATION ON THE MESOSCALE - ELEMENTSOF THE THEORY AND EMPIRICAL CHARACTERISTICS

The continuous records of mesozooplankton biomass (with the spatial av eraging of pump track every 20 km) were carried out from the surface l ayer (2-6 m depth) over 5 transects in the western part of the Indian Ocean during the end of the north-east monsoon period. The spatial aut ocorrelation functions have shown that the average size of zooplankton heterogeneities on the mesoscale is close to 40 km. To model the fiel d of zooplankton biomass b(t, x) the model based on the equation of no n-conservative substance diffusion was applied: db/bt + u(db/dx) = k(d (2)b/dx(2)) + nb + a(t, x), where t is the time; x the horizontal coor dinate; u the velocity of mass transport by a current; k the coefficie nt of horizontal turbulent diffusion and n the normalised velocity of zooplankton growth. The field a(t, x) characterises the rest of the lo cal fluctuations of zooplankton biomass not associated with the mentio ned processes. The techniques of solving the equation based on the spe ctral theory of the random fields was solved by means of the evaluatio n of the field autocovariation functions. (C) 1997 Elsevier Science B. V.