Documentation on Bottom Variables

[Sandra Slead]

Hello, 

Is there any formalized documentation available on how the _bottom variables are calculated/included in the output for the GOFS 3.1 Dataset (in particular, GLBy0.08 exp. 93.0)? 

I found this forum post, which is helpful for understanding the interpolation from GLBb0.08 to GLBy0.08, but I am wondering if there is additional documentation on what happens in the model between the last standard depth and the seafloor. 

Thank you very much,

Sandra

[Alan Wallcraft]

As the forum post you linked to says:

The GLBy0.08 41-layer archive file is SAMPLED at fixed depths (including 1500 m an d 10m above the GLBy0.08 bottom) using a specified profile type, the 41 layer velocities are first averaged from the cell edges to the cell center (where T & S is defined).

The bottom velocities are SAMPLED at 10 m above the bottom, using profile type PCHIP (piecewise cubic hermite interpolation between layer centers).

In shallow water (certainly shallower than 100n and probably shallower than 500 m) there will be multiple thin layers near the bottom and the velocity will represent 10 m above the bottom well.  We sample at bpttom+10m because our bottom boundary layer for quadratic bottom friction is 10 m.

In deep eater (certainly below 1500 m) HYCOM typically has a very thick bottom active layer and  bpttom+10m represents the average over that layer (e.g. over perhaps the bottom 1,000 m in some cases).

Alan.