MODELING THE EFFECT OF PHYSICAL VARIABILITY ON THE MIDWATER CHLOROPHYLL MAXIMUM

A coupled model, employing turbulence closure physics and cell-quota t hreshold limitation biology, has been used to simulate the evolution o f the vertical distribution of phytoplankton in a seasonally stratifie d shelf sea. Predictions are compared with observations from the North Sea. Variations in surface wind stress, which episodically weaken the thermocline barrier to nutrient input to the photic zone, are shown t o make an important contribution to the formation of a midwater chloro phyll maximum in Summer.