[MITgcm-support] Backtrace error while implementing NOBCS

Fri Aug 20 07:29:03 EDT 2021

Hi Kunal,

I think that specifying a second western open boundary is not possible with the current code (you’d need a second input file), so what you are doing is probably the best you can do. (if you don’t want to add you boundary values as surface fluxes).

Martin

> On 20. Aug 2021, at 11:53, kunal madkaiker <kunal.madkaiker02 at gmail.com> wrote:
> 
> I am attaching 2 plots. I have 3 open boundaries in south, west and east (fig1.gif). I am trying to force S,T,U and V from NOBC throughout in head bay of Bay of Bengal (fig2.gif, bathymetry in head bay, dark blue line resembles current OB_Jnorth).
> 
> For now I am only forcing in XZ direction. If I include YZ (east-west), then it'll get a bit complicated. I am not able to figure that out.
> 
> Regards,
> Kunal
> 
> On Fri, Aug 20, 2021 at 10:07 AM Martin Losch <Martin.Losch at awi.de> wrote:
> 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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