[ncl-talk] Regridding from OSGB spatial coordinate to Latitude-longitude in rotated pole coordinates

[Dave Allured - NOAA Affiliate]

Does your file contain its own lat and lon coordinate arrays?  You will
need to check this yourself with ncdump or NCL plus print commands.

If the file has its own coordinate arrays, then do not regrid or
reproject.  Doing that will lose detail and reduce the quality of the
plotted image.  NCL is quite capable of directly displaying any data with
attached coordinate arrays, and it does not need to know anything about the
projection of the data.  Please see documentation for "Plotting data on a
map" for much more information about aligning data on a map plot.

    https://www.ncl.ucar.edu/Applications/plot_data_on_map.shtml

If the coordinate arrays in the file are two dimensional, then see example
3, "Curvilinear grid".  When you have 2-D coordinates, they must be passed
to the NCL plot routine with special attributes *lat2d* and *lon2d*, or
alternatively *sfXArray* and *sfYArray* attached to the plot resource
variable.  Note that 1-D coordinates do not need this special treatment
because they are normally attached directly to the data variable to plot.


On Thu, Feb 25, 2021 at 8:24 AM S Br via ncl-talk <ncl-talk at mailman.ucar.edu>
wrote:

> Hi All,
> I have a set of regional gridded data in the British National Grid (OSGB)
> spatial coordinate system. I am looking to use this data in NCL but the
> projection is not correctly displayed? Could it be possible to regrid this
> data to Latitude-longitude in rotated pole coordinates or to a regular
> lat/lon grid.
>
> I would like to mention that these data sets are generated using the Iris
> package in Python. The data is correctly displayed in Python but not in NCL.
>
> For your convenience I have attached here a sample NetCDF file.
>
> Thank you.
> SBR
>
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