I’m trying to set up a new regional configuration with open boundaries, using release 4.0.5. (Probably switching to 4.2_RC as soon as available.)
After quite some testing there are remaining questions, for which I hope to get some input from the community. In the following, I try to summarize, what I did so far, what works and what doesn’t.
- First of all, installing the code and reproducing the test configuration AMM12 works!
- The new configuration has three straight open boundaries (N,W,S - coast in the east) that I define using the nambdy_index option with automatic definition of the boundary locations by setting nbdyind = -1 in all three nambdy_index. From ocean.output, I see that these boundaries are correctly identified.
- Running with closed boundaries works.
My aim is to prescribe temporally varying boundary conditions for 3D velocities, temperature, salinity and SSH (tides might follow at a later stage - I leave them out for now).
The core question I am struggling with is: What is the correct structure of the boundary conditions to be provided?
I tried several options from boundary data provided on the native model grid to using all the (seemingly) available options of interpolation from the original grid of the boundary data (weights, land/sea mask and vertical interpolation), and everything in between, all failing at some (different) point.
Additionally, I came across two particular problems:
- The velocities are full velocities, so I set ln_full_vel = .true. . Doing so leads to segmentation faults. This seems to be connected to undefined
dta_alias%v2din subroutine bdy_dta
IF( bf_alias(jp_bdyu3d)%ltotvel ). I can overcome this by setting cn_dyn2d to something else than ‘none’ (although ‘none’ would be the logical choice) and nn_dyn2d_dta = 0 . Is this a bug or am I misunderstanding something here? [I saw similar things being done in older configurations in NEMO3.6]
- I’d also like to prescribe SSH but this is not possible with full velocities - correct?
I’ve been using NEMO for quite a while now but am new to BDY and appreciate any input that might help to get me through this process.