I am working with NEMO 4.2.0 on a regional configuration of the Mediterranean Sea (≃ 7km; 75 z-vertical levels with partial steps). Based on the NEMO 4.2.0 reference manual (NEMO ocean engine | Zenodo), I almost finalized my namelist, but I am still unsure about some parameters. To be more specific:
Regarding the top friction (namdrg_top):
Since I represent tides but not waves, I wonder if I should set the background kinetic energy at the surface to zero (rn_ke0).
With the logarithmic boundary layer formulation (ln_loglayer=.true.), how much is the model solution sensitive to the surface drag coefficient? To be more specific, I have been doing some previous simulations using rn_Cd0 = 2.5e-3 instead of 1e-3 in the reference namelist. Is it worth decreasing this value to match the reference namelist, or is the difference negligible?
Regarding the bottom boundary layer scheme (nambbl): The NEMO documentation clearly describes the scheme and its added value in z-coordinate configurations. However, it is unclear to me whether I should choose only the diffusive, the advective scheme, or both.
Horizontal tracer advection and diffusion schemes: Based on the namelist of other NEMO simulations from my laboratory, I have selected the following:
For the advection (namtra_adv): the FCT scheme (ln_traadv_fct=.true.), with nn_fct_h=4 and nn_fct_v=2.
For the diffusion (namtra_ldf): a laplacian operator (ln_traldf_lap=.true.) applied in the iso-neutral direction (ln_traldf_iso=.true.).
However, it is unclear to me if this is the right choice. From what I understand from the reference manual, it depends on the configuration, but would you have some advice or references to make a sound choice?
Horizontal momentum advection and diffusion schemes: I wonder the same as for the tracers. So far, I have chosen the following:
For the advection (namdyn_adv): the vector form (ln_dynadv_vec=.true.), with the een scheme for the vorticity (ln_dynvor_een=.true. in namdyn_vor)
For the diffusion (namdyn_ldf): a bi-laplacian operator (ln_dynldf_blp=.true.) applied in the geopotential direction (ln_dynldf_hor=.true.)
If you have any advice or recommendation on these points, I would be very glad to read it.
Thank you in advance,