[ncl-talk] Question about PopLatLon: reamp regular lat-lon grid to POP grid

[Dave Allured - NOAA Affiliate]

It looks like this data set uses a special code value over land, and that
is distorting adjacent grid points through PopLatLon.  Examine the input
file, find out what the special code is, and set those values to the data
set missing value (x at _FillValue) in NCL memory, before calling PopLatLon.

I can not answer your second question about a file location.  You will not
need that other file if you can solve the special code problem above.


On Wed, Jun 17, 2020 at 4:50 PM Yuntao BAO via ncl-talk <
ncl-talk at mailman.ucar.edu> wrote:

> Dear NCL-talk,
>
> I use PopLatLon function to remap SST with a regular 1x1 lat/lon grid to a
> POP grid. To perform the remapping, I use the POP weight file "*map_1x1d_to_gx1v6_bilin_da_100716.nc
> <http://map_1x1d_to_gx1v6_bilin_da_100716.nc>" downloaded from *
>
> https://svn-ccsm-inputdata.cgd.ucar.edu/trunk/ncl/
>
>
>
>
>
> I successfully get the result, the new SST with a gx1v6 POP grid. But the
> problem is that* the new SST data has many unrealistic values in most of
> the continental margin (shown in Fig. b), these values are much less than
> it should be. *
>
> I don't know what may cause this problem. Do you have any idea about what
> may cause this problem? I think maybe the POP weight file accounts.
>
>
>
> The remapping results of the example *lat2pop_1.ncl *on NCL webpage has
> no such problem. This example used a different POP weight file *"map_1x1d_to_gx1v3_bilin_da_010808.nc
> <http://map_1x1d_to_gx1v3_bilin_da_010808.nc>". I tried to download this
> weight file, but I can't find it anywhere. Could you please guide me to the
> location of this former POP weight
> file "map_1x1d_to_gx1v3_bilin_da_010808.nc
> <http://map_1x1d_to_gx1v3_bilin_da_010808.nc>" ?*
>
>
>
> I would appreciate if you can help! Looking forward to your reply!
>
> Best regards,
>
> *Yuntao Bao*
>
>
> *Appendix:*
>
> *This is the link of the example lat2pop_1.ncl:*
>
> https://www.ncl.ucar.edu/Applications/Scripts/lat2pop_1.ncl
>
>
>
> *These are the plots before and after remapping:*
>
> <snip>
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