Mellor–Yamada parameterization

A parameterization of a complex model for turbulent flows in the planetary boundary layer.

A series of simplifications of the full turbulence model to remove complex terms and form a closed set of equations leads to a hierarchy of so-called closure models of decreasing complexity labeled level 4 through level 1. The level 2.5 model is widely used; it incorporates only one additional equation and produces conventional turbulent fluxes.