An Eulerian model of phytoplankton photosynthetic response in the upper mixed layer

An Eulenan model of an upper mixed layer forced by dynamic andconvective processes is combined with a temporally responsivephotoadaptation model of photosynthesis. Incident radiationis divided into photosyntheticalJy active and inactive componentsto distinguish between biological and physical forcing. Thephysical model is initialized to simulate conditions in LakeTiticaca on August 12, 1982 Model output provides the time courseof water column temperature, phytoplankton photoinhibition andrelative phytoplankton carbon fixation as depth contours forcomparison with published observations. The predicted and observedtemperature profiles generally agree; diurnal changes in specifichumidity are required to more accurately specify heat loss.The predicted photoinhibition resembles the observed photosyntheticstate of the natural community based on fluorescence, but themodeled recovery from photoinhibition is too rapid. This discrepancyalso affects the comparison between predicted and observed bottledeterminations of carbon fixation. The basic formulations inthe model provide approximate fits to field observations. Ifmore complete information on physical and biological initializationsand on temporal forcing were available, the basic formulationscould be refined