I have a netCDF file and would like to convert it to LAT-LON coordinates. 1) I do not know the projection in the file but from the website of the data provider, the data is on a polar-stereographic (PS) grid covering North America and adjacent waters with a 10 km resolution at 60 degrees north. 2) How can I project to latlon using a suitable coordinate system for the north pole?

Here is my sample file:


  • Any chance of something smaller than 750Mb to download? Maybe just a few coordinate points in the given coordinate system?
    – Spacedman
    Commented Feb 5, 2016 at 16:35
  • @Spacedman I just added a smaller file size `3MB
    – code123
    Commented Feb 5, 2016 at 18:54
  • Unfortunately, GDAL 2.1.0 can not read the reduced file.
    – AndreJ
    Commented Aug 16, 2016 at 9:07

2 Answers 2


The projection looks like it matches this custom entry in http://spatialreference.org:

    GEOGCS["GCS_Coordinate System imported from GRIB file",


Depending on the software you have at hand, that should be usable in one format or another.

If you want to transform a shapefile in lat-long to this grid system, then try this:

target = "+proj=stere +lat_0=90 +lat_ts=60 +lon_0=249 +k=1 +x_0=0 +y_0=0 +a=6371229 +b=6371229 +units=m +no_defs"
shgrid = spTransform(shlatlong, CRS(target))

plot the shgrid object to make sure. You might get problems if the shapefile crosses the dateline or rounds the pole...

Not knowing how you've loaded your netCDF into R, I can't be sure how to crop it, but if its a raster then mask from the raster package probably does the trick.

  • it is true that It might not be a good idea to transform a grid over the pole to lat-long but I have a shapefile in latlong which I would like to use in cropping the netcdf file. Here are the bbox coordinates of the shapefile: xmin -141.01807 xmax -52.61941 ymin 41.68144 ymax 83.13550 Can you show me how to use these coordinates to crop the file attached here? I can also include the shapefile in the attachment if you need it.
    – code123
    Commented Feb 5, 2016 at 17:41
  • Do you have QGIS, ArcGIS, R, something else, or do you want to do all this with GDAL command-line tools?
    – Spacedman
    Commented Feb 5, 2016 at 18:03
  • I have R. I can use raster and rasterVis packages for doing it if you give me directions. gdaltransform -s_srs SR-ORG:8237 -t_srs epsg:5937 2013_000_CaPA_continental_v2.3-analyse_final_10km_6h_APCP.nc 2013.tif gdal does not recognize SR-ORG:8237. It issues an error.
    – code123
    Commented Feb 5, 2016 at 18:12
  • target flips my map upside down. It is a map of Canada
    – code123
    Commented Feb 5, 2016 at 18:33
  • Ooh. Possibly because the grid system reference has Y increasing southwards (on the Canadian side of the pole anyway). Sorry, but I can't download a 750Mb file to play with this.
    – Spacedman
    Commented Feb 5, 2016 at 18:38

To reproject raster into another spatial reference the gdalwarp utility can be used. The command can be looks like:

gdalwarp -t_srs 'EPSG:4326' -overwrite \
NETCDF:"your file.nc":your_subdataset subdataset_4326.tif

Choose another projection if you wish.

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