In 1997, i wrote a simple 1D mixing layer model with second order closure: Turbulent kinetic energy was prognostically computed. The model was representing correctly the seasonal cycle although the set of coefficients were chosen somewhat arbitrarily.

I studied the effect of the diurnal cycle on the depth of the mixing layer for a seasonal period. No noticable change were noticed.

Here is presented a seasonal cycle for the top 100m. Initally the gradient of temperature is 5 degrees C. On average, the depth of the Ekman layer is about 30 m. On top of the stable Ekman layer, there are seasonal variations directly due to primary unstability (cold water on top of warm water) that deepens the mixed layer. |

A five year seasonal simulation. The model reaches a climatic equilibrium after the second year. |