Optical model for use in oceanic ecosystem models

Modeling the plankton ecosystem requires a code for simulating the profile of irradiance from the chlorophyll profile at each time step of the integra tion. We have compared two existing codes with data from the Biogeochemical Ocean Flux Study: the Hydrolight radiative transfer model is accurate but too slow to use interactively in ecological models; Morel's [J. Geophys. Re s. 93, 10,749 (1988)] empirical model is much faster but produces substanti al error. We have developed a streamlined version of the Hydrolight radiati ve transfer model that is 20 times faster than the full Hydrolight code, wh ile limiting errors to less than 12% within the euphotic zone. This new cod e is both fast and accurate and is, therefore, suitable for use interactive ly in oceanic ecosystem models. (C) 1999 Optical Society of America. OCIS c odes: 010.0010, 010.4450.