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odd missing values when using convert_mpas for limited area MPAS


New member

I was trying to interpolate a 3km regional limited area MPAS atmosphere forecast to a lat-lon grids with convert_mpas. The 3km meshes is a relatively large domain covering the whole US CONUS. I noticed there are some odd missing values (straight white lines in attached figures) close to the north boundary when interpolating to 1/8 degree or 1/16 degree lat-lon grids. convert_mpas was running on 1 node with 40 cores as:

srun ./convert_mpas

I am wondering if this is from incorrect set up or a potential bug?

This is a known issue with the convert_mpas tool when processing limited-area domains. See, for example, section 4.5 of the online tutorial (MPAS Tutorial — Practice Session Guide) with this text:
As mentioned in the lectures, the convert_mpas program may produce some interpolation artifacts as of the time of this tutorial. We expect to have this fixed in the near future, but for now, we can ignore any interpolation artifacts and animate through all time slices of several model diagnostic fields in ncview to gain confidence that our regional simulation is producing plausible results.
Apologies for not doing a better job of making this known!

We do know how to fix this issue, and it's just a matter of getting the time to implement the changes -- essentially, changing the way that we identify the MPAS mesh cell that contains a target (lat,lon) location.