Three dimensionalization of stratified shear instability in the cabbeling regime

In this talk I will discuss direct numerical simulations of shear instability in the cold water regime, or in other words the regime in which the range of temperatures includes the temperature of the density maximum (around 4 degrees Centigrade). In this regime, the mixing of two fluid parcels can lead to a child fluid parcel with a larger density than either parent parcel. This phenomenon is called cabbeling. I will demonstrate that cabbeling fundamentally alters the three dimensionalization of shear instability. I will subsequently show various properties of the fully three-dimensionalized state, which has many hallmarks of turbulence, but does not have a well developed inertial subrange. I will discuss how entrainment can drive continuing instabilities in the three-dimensionalized region, as well as how the vertical transport of both scalars and momentum is modified from the classical picture of natural waters. Time permitting I will present some new ideas of how parametrizations for this regime may be constructed for basin scale lake models.