NOAA-GFDL/pace

rename 'ks' variable in Pace

Opened this issue · 3 comments

The ks variable in Pace and FV3 is supposed to designate the topmost layer in which the bk of the eta pair becomes zero. That layer and above is known as the sponge layer. It makes sense to rename the variable in Pace to be more descriptive as it does not have the same meaning as is and js.

This variable may not be necessary for our current purposes; any model component that needs it can easily re-compute it from the ak/bk coefficients. So we could just remove it.

Minor correction: above ks is where the reference coordinate becomes a pure-pressure coordinate and surface pressure has no influence. It is not necessarily the sponge layer, in which additional damping is applied near the upper boundary.

@lharris4 - thanks for the clarifications! BTW, @oelbert and I chatted about the need for this variable and maybe removing it before deciding to open a discussion and get your input.