A 3-DIMENSIONAL VERTICAL MIXING MODEL APPLIED TO LAKE KINNERET

The two-dimensional, two-layer Eulerian shallow water equations have b een coupled with a Lagrangian one-dimensional vertical mixed-layer tur bulence closure scheme. Integrated with the advection-diffusion equati on for heat, a new approach to a three-dimensional vertical mixing mod el is presented for Lake Kinneret. Previous Eulerian-Lagrangian models (SCHOPF & CANE 1983) explicitly incorporated the Lagrangian terms, ty pically the upwelling/downwelling velocities, into the hydrodynamic Eu lerian flow equations. In the present approach the equations are impli citly coupled, while still forming a closed system. Subsequently only the two-dimensional two-layer hydrodynamic equations are solved on a g rid covering the entire lake. The thermal structure on the other hand is not restricted by the two-layer momentum equations, but is independ ently defined by a system of layers according to the level of turbulen ce in the water column. Furthermore, the thermal structure can be solv ed for chosen transects, greatly alleviating the computational expendi ture for solving large lake systems. The model computes the vertical t hermal structure across the lake, and hence the depth of, and temperat ure and density jump across the thermocline, key variables in any wate r quality control model.