ESTIMATION OF NET PHOTOSYNTHETICALLY AVAILABLE RADIATION OVER OCEANS FROM SATELLITE DATA - APPLICATION TO A DYNAMIC-MODEL OF A PLANKTON BLOOM IN THE ATLANTIC-OCEAN

A radiative transport model has been developed for the simulation of p hotosynthetically available radiation (PAR) flux density transfer in c lear and cloudy atmospheres. Vertical profiles of temperature, pressur e, and atmospheric constituents by globally distributed radiosonde mea surements with multiple cloud layers of different types and fractional coverages are used to represent the natural variability of clear and cloudy atmospheres. A multivariate analysis for the parametrization of (net) surface PAR flux densities as a function of the solar elevation and the system reflectivity measurable by satellite sensors was carri ed out. The resulting retrievals show standard errors less than 35 Wm- 2 for cloudy scenes and 5 Wm-2 for Clear skies. The regression algorit hms were applied to NOAA AVHRR satellite measurements and compared to simultaneously recorded shipborne data logs during a cruise of the UK research vessel Charles Darwin in May 1990 in the north Atlantic. The impact of the satellite net PAR maps on two-dimensional (2D) dynamical phytoplankton modeling is described