[ncl-talk] plotting two very similar datasets with very different outcomes

[Adam Phillips]

Hi all,
Just to update everyone on this issue: Adam and I communicated offline.
Debugging efforts on both of our parts were unsuccessful. My best guess is
that a graphics bug is triggered due to the specific grid chosen and the
gradients within the regridded data, and there is seemingly no way around
it.
Adam

On Mon, Jul 20, 2020 at 8:44 PM Adam Herrington via ncl-talk <
ncl-talk at mailman.ucar.edu> wrote:

> I've a 2D field ("bar") that has dimensions (ilat,ilon) which is on a
> regional curvilinear grid [30S,30N],[30E,30W]. I created this field through
> using ESMF remapping from a global grid to the regional rectilinear grid.
> Attached are two plots in which the only difference is the method of
> remapping "bilinear" v. "conservative":
>
> When I plot using the default cnFillMode = "AreaFill" it gives me the
> correct field for bilin, but nothing for conservative remapping.
>
> [image: temp_contours.areafill.png]
>
> When I plot using cnFillMode = "CellFill" and supply the vertices from the
> SCRIP file:
>
>      res at sfXCellBounds = vf->grid_corner_lon
>      res at sfYCellBounds = vf->grid_corner_lat
>
> it gives me a weird red strip through the central meridian of the conserve
> case.
>
> [image: temp_contours.cellfill.png]
>
> When I sift through the data, there are no extreme values that pertain to
> that red mark. There are no missing values! I've tried translating the
> reference grid away from the prime-meridian and it still is there at the
> center of the composite. Here's the PDF of values for sanity:
>
> [image: temp_pdf.png]
>
> I'm including the two netcdf files here in case someone is interested in
> helping me track down this odd behavior. I'm also including the ncl script
> I'm using to plot these two datasets.
>
> Adam
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-- 
Adam Phillips
Associate Scientist,  Climate and Global Dynamics Laboratory, NCAR
www.cgd.ucar.edu/staff/asphilli/   303-497-1726

<http://www.cgd.ucar.edu/staff/asphilli>
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