This model provides a dynamic simulation of the Sverdrup (1953) paper on the vernal blooming of phytoplankton.
The model simulates the dynamics of the mixed layer over the year, and illustrates how it's depth variation leads to conditions that trigger the spring bloom. In order for the bloom to occur, production of algae in the water column must exceed respiration.
This can only occur if vertical mixing cannot transport algae into deeper, darker water, for long periods, where they are unable to grow.
Sverdrup, H.U., 1953. On conditions for the vernal blooming of phytoplankton. J. Cons. Perm. Int. Exp. Mer, 18: 287-295