[MITgcm-support] using RBCS to generate flow

[Jean-Michel Campin]

Hi Caroline,

Could you send few parameter files that you are using when trying to
work with checkpoint64 code ?
it would be "data", "data.pkg" and "data.rbcs".

Cheers,
Jean-Michel

On Tue, Dec 24, 2013 at 01:54:37PM +0100, katsman wrote:
> Dear MITgcm developers,
> 
> Over the past years, I used the RBCS package to generate a flow in
> an (otherwise unforced) basin representing the Labrador Sea, by
> restoring the flow to a prescibed 3D-temperature and velocity field
> in a corner of the basin (T and velocity in geostrophic balance).
> This worked excellent in a (admittedly old) checkpoint58-version in
> which we manually added a restoring term on U and V analogous to the
> programmed T, S part.
> 
> When I got a new workstation I thought it time to upgrade to the
> most recent MITgcm version, but I cannot get the package to work in
> the same way (and I tried many things over the past months, so I am
> getting a bit desperate...).
> 
> The new checkpoint64 is supposed to be able to restore T,U and V,
> but I find that - when I prescribe my T,V fields again as before -
> in the sponge region defined by the mask, T is restored fine, while
> V is restored fine only during the first few timesteps of the
> simulation. Then a purely baroclinic U develops as well, while V
> becomes barotropic (despite RBCS acting on it). Intriguing, but not
> what I wanted.
> 
> A test that really makes me think there is a bug in the rbcs package
> rather than me doing something stupid is that when I only restore T
> with a gradient in x, I expect to see a purely baroclinic V develop
> in geostrophic balance with that. In stead, nothing happens (I can
> run it for a month, no flow develops at all).
> 
> One of the earlier versions (c62) has yet another version of the
> RBCS package. When I do a test with T-restore only (U,V is not
> standard in that one), a baroclinic flow does develop obeying
> geostrophy.
> 
> Any ideas what is wrong here? I checked - the  model does frequent
> the appropriate lines of code  in rbcs_add_tendency in the c64
> version  to change the gV parameter - I suspect somewhere in the
> code U and V are mixed up. Notably, the baroclinic flow that
> develops in the sponge region is roughly the same strength as the V
> I prescribe
> 
> Any ideas?? (if the description is unclear I can send pictures)
> 
> Thanks in advance & happy holidays
> Caroline
> 
> 
> 
> 
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