ONE-DIMENSIONAL NUMERICAL-SIMULATION OF PRIMARY PRODUCTION - LAGRANGIAN AND EULERIAN FORMULATIONS

It has been argued (Wolf and Woods, in Toward a Theory On Biological-P hysical Interactions in the World Ocean, Rothschild, (ed.), 1988) (WW8 8) that phytoplankton growth models are sensitive to Lagrangian effect s because populations at a given depth and time contain a wide distrib ution of photoadaptive properties. On the other hand, Lande and Lewis (Deep-Sea Research, 36, 1161-1175, 1989) (LL89) have claimed that for a different photosynthetic model, this distribution of properties can be adequately represented by a mean value in a much simpler and more e fficient Eulerian formulation. This study compares Lagrangian and Eule rian integrations of these two different models of photosynthesis unde r two mixing regimes. For relatively weak mixing, the growth rate pred icted by the different formulations of the two models is small (less t han or equal to 5%). In vigorously mixed conditions, Lagrangian effect s cause a significant (similar to 20%) reduction in the mean growth ra te of the WW88 model, while the differences in the two integrations of the LL89 model differ only slightly (similar to 3%). The apparent dis crepancy in the comparisons between Lagrangian and Eulerian integratio ns of the two different photosynthesis models is a result of different parameterizations of photoadaptive reaction kinetics.