The primary production module in the marine ecosystem model ERSEM II, with emphasis on the light forcing

New elements in the primary production module of ERSEM II relative to ERSEM I are described. The main changes are the inclusion of picoalgae and dinoflagellates as additional functional groups, the decoupling of carbon-and nutrient-uptake kinetics and the refining of the light dependency of the primary producers, with emphasis on the last. The results of a reference run are compared with measurements. The consequences of using production-irradiance (p/l) relations assuming a different degree of photoinhibition in calculating net annual primary production are shown in a sensitivity analysis, and it is concluded that a p/I relation with a high degree of photoinhibition leads to clear underestimates of primary production in turbid coastal waters. (C) 1997 Elsevier Science B.V. All rights reserved.