34.5 bryan_lewis_horizontal

This is a hybrid mixing scheme in the sense that it affects only tracers and not velocity. It specifies the horizontal tracer diffusivity A_h to be a function of depth given by the Bryan and Lewis (1979) form

$$\diff\_cet_k = \diff\_cnt_k = (ahb + (ahs-ahb)\exp(-\frac{zt_k}{50000.0}))\cdot 1.0 \mbox{x} 10^4,$$ (34.70)

with $ahs=5.0\mbox{x}10^3\; m^2/sec$ and $ahb=1.0\mbox{x}10^3\; m^2/sec$. The diffusivities $diff\_cet_k$ and $diff\_cnt_k$ are functions of k. It should be noted that the functional relationship can easily be changed to whatever vertical dependence is desired. Values required for this option can be changed through namelist. Refer to Section 14.4 for information on namelist variables.