[ncl-talk] Clarifcation and repost: masks from shapefile; problem at 90N and 180E

[Denise Worthen - NOAA Affiliate]

Hi All,

In my attempt to create a lightweight test case for posting, I made it
clear as mud what I am attempting to do. Mary suggested I repost my query
with more explanation of what I am trying to accomplish and the problem I
am seeing.

I am using NCL's shapefile mask function to create a file containing a
single mask for the Arctic Ocean. The mask will have different values for
each of the Arctic Ocean's marginal seas. Once I create the mask, I can
regrid it using ESMF weights to the tripole grid that the model is on. Then
I can use the tripole mask to calculate various quantities for the marginal
seas of the Arctic from the model. The regridding and statistics are done
in F90 routines outside of NCL.

The script make_arcticregs.ncl creates a file with a mask for each Arctic
region and a "total" mask which is the sum of all the individual masks. It
does a lot of what it does using NCO. There is probably a simpler NCL-way
of doing it though.

The script plot_arcticregions.ncl makes a polar plot of the "total" mask
using the file produced by the 'make' script. The attached figure shows the
result. There is a missing wedge along 180E and at 90N. The figure shows
the case with a reduced number of regions (3) and a second figure shows all
10 regions.

The only problem I have is the missing wedge. I can actually fix it fairly
easy outside of NCL but I wasn't sure why the mask creation inside of NCL
was resulting in the missing wedge.

Thanks,
Denise.
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