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.