35.2.1.4 Summary of namelist parameters

In summary, the namelist parameters for the Held and Larichev scheme, which are set in the namelist /ncdiff/, are the following:

1.

D_b = depthbot is the maximum depth over which the vertically averaged Richardson number is computed. The default is depthbot = 1000m. In regions shallower than depthbot, the lower limit on the vertical average defaults to the local model depth.

2.

D_t = depthtop is the minimum depth over which the vertically averaged Richardson number is computed. The default is depthtop = 100m. In regions where the depth is shallower than depthtop, the scheme returns a diffusivity equal to the value athkdf input to the namelist.

3.

diffmin is the minimum diffusivity returned from the scheme. The default is diffmin = 10⁶ cm²/sec.

4.

diffmax is the maximum diffusivity returned from the scheme. The default is $diffmax = 2 \times 10^{7} cm^{2}/sec$. Note that the effective value of the maximum diffusivity employed is constrained by the steep slope conditions discussed in Section 34.1.9.

5.

diffint sets the frequency, in model time steps, on which the nonconstant diffusivity will be updated. The default is diffint = 5.