[MITgcm-support] Backtrace error while implementing NOBCS

[Martin Losch]

not much simpler:
 OB_Jnorth = 549*0, 2*-100,-99,2*-98,6*-97,2*-96,4*-95,2*-94,

but wouldn’t that also require some open points in east-west direction? see here: <https://mitgcm.readthedocs.io/en/latest/phys_pkgs/obcs.html#a-more-complex-example>


M




> On 19. Aug 2021, at 16:15, kunal madkaiker <kunal.madkaiker02 at gmail.com> wrote:
> 
> Thank you Gus. Martin, rightly pointed out, the error was caused in the NOBC boundary file as I had 1 open point (1x48x2), but it was not in the required 660x48x2 format. I added zeros for every other point and it worked! Thanks a lot Martin.
> 
> I am trying to keep 19 open points in NOBC boundary through data.obcs:
>  OB_Jnorth(550)=-100,
>  OB_Jnorth(551)=-100,
>  OB_Jnorth(552)=-99,
>  OB_Jnorth(553)=-98,
>  OB_Jnorth(554)=-98,
>  OB_Jnorth(555)=-97,
>  OB_Jnorth(556)=-97,
>  OB_Jnorth(557)=-97,
>  OB_Jnorth(558)=-97,
>  OB_Jnorth(559)=-97,
>  OB_Jnorth(560)=-97,
>  OB_Jnorth(561)=-96,
>  OB_Jnorth(562)=-96,
>  OB_Jnorth(563)=-95,
>  OB_Jnorth(564)=-95,
>  OB_Jnorth(565)=-95,
>  OB_Jnorth(566)=-95,
>  OB_Jnorth(567)=-94,
>  OB_Jnorth(568)=-94,
>  OB_Jsouth=660*1,
>  OB_Iwest=480*1,
>  OB_Ieast=480*-1,
> 
> Is there a simpler way to feed it? I referred to the OBCS section in the manual and tried a few things but it didn't work out. Any suggestions?
> 
> Regards,
> Kunal
> 
> On Thu, Aug 19, 2021 at 7:32 AM Martin Losch <Martin.Losch at awi.de> wrote:
> Kunal,
> 
> the error message (as usual) means that there are not enough records in your input file (‘OBNu.seaice_obcs’)
> you domain dimensions are (according to STDOUT.0000):
> (PID.TID 0000.0001)      nPx =   10 ; /* No. processes in X */
> (PID.TID 0000.0001)      nPy =    6 ; /* No. processes in Y */
> (PID.TID 0000.0001)      nSx =    1 ; /* No. tiles in X per process */
> (PID.TID 0000.0001)      nSy =    1 ; /* No. tiles in Y per process */
> (PID.TID 0000.0001)      sNx =   66 ; /* Tile size in X */
> (PID.TID 0000.0001)      sNy =   80 ; /* Tile size in Y */
> (PID.TID 0000.0001)      OLx =    4 ; /* Tile overlap distance in X */
> (PID.TID 0000.0001)      OLy =    4 ; /* Tile overlap distance in Y */
> (PID.TID 0000.0001)      nTx =    1 ; /* No. threads in X per process */
> (PID.TID 0000.0001)      nTy =    1 ; /* No. threads in Y per process */
> (PID.TID 0000.0001)       Nr =   48 ; /* No. levels in the vertical   */
> (PID.TID 0000.0001)       Nx =  660 ; /* Total domain size in X ( = nPx*nSx*sNx ) */
> (PID.TID 0000.0001)       Ny =  480 ; /* Total domain size in Y ( = nPy*nSy*sNy ) */
> 
> So your input file for the OBCS pkg for the northern or southern boundary for a 3D field like temperature needs to have a field with the dimensions (t,z,x) = (nrec,48,660) and for the eastern/western boundaries (nrec,48,480). nrec needs to be at least 1 (for constant obcs forcing). This is independent of the number of actual boundary points. I.e. if you have only one open boundary point (OB_Jnorth(550)=-100,) your file still need the entire array, it can be zero everywhere except for the point i=550 (for i starting at 1, for i starting a 0 as in python, it should be at 549).
> 
> For a 2D field like sea ice velocity you drop the z-dimension (but I guess you only give you files these names, and don’t use sea ice).
> 
> does that make sense?
> 
> Martin
> > On 18. Aug 2021, at 15:44, kunal madkaiker <kunal.madkaiker02 at gmail.com> wrote:
> > 
> > Dear All,
> > 
> > I am using MITgcm for regional analysis. I have kept a single OB point on the northern boundary. But I keep getting backtrace error and model blows.
> > 
> > Error termination. Backtrace:
> > At line 1946 of file mdsio_read_section.f (unit = 9, file = 'OBNu.seaice_obcs')
> > Fortran runtime error: Non-existing record number
> > 
> > I have gone through similar asked questions on the support group and checked accordingly. The dimensions for my NOBCS pt is 1x48x2 (nx x nz x nt). I have prepared the T,S,U and V data and written as real*8. But still error persists.
> > Attaching my data, data.exf, data.obcs files. Kindly assist.
> > 
> > Regards,
> > Kunal
> > <data><data.obcs><data.exf><STDOUT.0000>_______________________________________________
> > MITgcm-support mailing list
> > MITgcm-support at mitgcm.org
> > http://mailman.mitgcm.org/mailman/listinfo/mitgcm-support
> 
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