[MITgcm-devel] exf: u/v-wind interpolation and cubed sphere

[Martin Losch]

Hi Dimitris,

for benchmarking I successfully run the high_res cubed sphere on our  
XD1 with 27 cpus (its the ss216t_85x85 configuration), with monthly  
forcing, (the *194_92_12.bin files). We have moved the entire  
configuration to an IBM p690 and reran the identical experiment and  
get this:
> STOP in S/R exf_check_range
> STOP in S/R exf_check_range
> ERROR: 0032-184 MPI was not finalized  in routine unknown, task 10
> ERROR: 0032-184 MPI was not finalized  in routine unknown, task 11
We didn't save the output in STDOUT.0021 and STDOUT.0023, but  
appearently the u/vwinds are wrong (order 10e11) at i=85,j=1 for one  
tile (I think it was tile 96), and consequently wrong at i=85,j=86  
for another tile because of exchanges, also at i=0,j=1 and i=1,j=1 at  
different tiles, and this is reproducible (on the p690 in Hannover).  
Task 10 owns tiles 81-88 task 11 tiles 89-96; I cannot be sure, but I  
suspect that the grid points that cause the problem are the four  
points around the north pole?

[BTW, should i change exf_check_range, so that the STOP command is  
executed *after* the bi,bj-i,j-loops have finished? That way we would  
get the numbers of more than one grid point before the system stops.  
Works nicely for me.

When we do not read uwind/vwind (that is, when these fields are  
zero), the problem goes away.

I suspect a problem in the interpolation routines, in particular  
lines such as
>                     if ( yC(i,j,bi,bj) .gt.
>      &                  (90-dyC(i,j,bi,bj)*8.9946e-06) )
>      &                  offset=2
But that just a wild guess. Do you have any ideas?

Martin

PS: Unfortunately I cannot reprdouce this with a simpler cs-setup.