[MITgcm-support] errors in OB location vs Mask

[Stefano Querin]

Hi Kunal,

just a wild guess...
As far as I remember, imposing (northern OBCS) to points with both land and water neighbors (on the eastern and western side) can give problems when MITgcm checks the overall OBCS configuration. You should alternate N and W OBCS, but you cannot do it in your specific setup.
Try to start with a single northern OB point (with land on both the W and E side), check if it works (it should); then try to add more OB points, with different locations, and see what happens.

Good luck!

Cheers,

SQ

P.S.: at that resolution, surface runoff/fluxes is a sound (and much easier) alternative.
P.P.S.: I think it is better to mask out those shallow isolated points/areas ("ponds") in the NE corner of your figure: they don't communicate with your main basin and they can be prone to unrealistic "extreme" conditions (e.g., overheating in summer).


> On 25 Aug 2021, at 15:07:23, kunal madkaiker <kunal.madkaiker02 at gmail.com> wrote:
> 
> Dear All,
> 
> I have a complicated topography on the northern side (fig2.gif attached), which I need to keep open. I am forcing in XZT (660*48*31) direction, where the first 550 points are zeros. 
> 
> The error I get is:
> (PID.TID 0000.0001) *** ERROR *** OBCS_CHECK:    58 errors in OB location vs Mask
> (PID.TID 0000.0001) *** ERROR *** S/R ALL_PROC_DIE: ending the run
> 
> I have referred closely to https://mitgcm.readthedocs.io/en/latest/phys_pkgs/obcs.html#fig-obcsexample <https://mitgcm.readthedocs.io/en/latest/phys_pkgs/obcs.html#fig-obcsexample> but I am unable to prescribe NOBC properly. 
> As explained in the example, when I prescribe values on the LAST land point of bathymetry, model runs properly but I don't see the effect of the OB cascading on S,T,U,V (seems like no NOBC given). 
> When I force values on the immediate wet points below, I get the above error. 
> 
> If I change OBCSfixTopo=.TRUE., to FALSE, errors increase from 58 to 63. I am not understanding how/why the model is showing 58 errors out of the 111 boundary points.
> 
> Currently, I have commented the OBNFiles and prescribed ref values through obcs_calc.f (s=0, t=20, u=0, v=-1)
> Attaching my data.obcs, STDOUT.0000 files. Also, I have listed bathymetry values for (I=549:660) along the northern boundary which I am attaching (Bay.txt).
> Kindly assist.
> 
> Regards,
> Kunal
> <Bay.txt><fig2.gif><STDERR.0000><data.obcs><STDOUT.0000>_______________________________________________
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