Remapping from UTM32 to lon-lat

Hi,

The attached netcdf dataset is derived from an observational product here at DMI that is on a regular UTM32 grid. I would like to regrid this to some other grid, using a regular 1x1 degree grid as an example in this case. The command that I have used is:

cdo remapnn,global_1 sample.nc foo.nc

cdo    remapnn (Abort): Unsupported projection coordinates (Variable: tas)!

What is going on here? Does CDO not support regridding with UTM? Is there anything I can do to make this work?

Note - I have made the metadata myself, with an attempt to follow CF conventions, with a lot of help from Chat. I (we) may be missing some key elements that are causing the problem.

Best wishes,

Mark

sample.nc (3.69 MB) sample.nc

Replies (7)

RE: Remapping from UTM32 to lon-lat - Added by Karin Meier-Fleischer 18 days ago

With version 2.4.4 it works good.

RE: Remapping from UTM32 to lon-lat - Added by Mark Payne 17 days ago

<blush> You're right. I was flipping back and forth between 1.99 rc1 and 2.4.4 without realising it, which created the bug. Apologies.

RE: Remapping from UTM32 to lon-lat - Added by Lina Neunhäuserer 4 days ago

I just experienced the same problem as Mark above. Using

cdo remapnn,lonlat_grid O3_utm32_hour01_day01_mon01.nc O3_lonlat_hour01_day01_mon01.nc

resulted in

cdo remapnn (Abort): Unsupported projection coordinates (Variable: O3)!

As I am using cdo version 2.5 (ubuntu) I cannot figure out what is going wrong here. Any support would be highly appreciated.
Best regards, Lina

Download all files

lonlat_grid (136 Bytes) lonlat_grid
O3_utm32_hour01_day01_mon01.nc (2.19 MB) O3_utm32_hour01_day01_mon01.nc

RE: Remapping from UTM32 to lon-lat - Added by Karin Meier-Fleischer 4 days ago

The used projection is UTM32 so you have to add the proj string to the grid description as follows.

First get the grid description from O3_utm32_hour01_day01_mon01.nc:

cdo griddes O3_utm32_hour01_day01_mon01.nc > gridfile_UTM32.txt

Add the proj_params string to gridfile_UTM32.txt:

gridtype  = projection
gridsize  = 570500
xsize     = 652
ysize     = 875
xname     = x
xunits    = "meter " 
yname     = y
yunits    = "meter " 
xfirst    = 275500
xinc      = 1000
yfirst    = 5231500
yinc      = 1000
grid_mapping = crs
grid_mapping_name = transverse_mercator
semi_major_axis = 6378137.
inverse_flattening = 298.257223563
scale_factor_at_central_meridian = 0.9996
longitude_of_central_meridian = 9.
latitude_of_projection_origin = 0.
false_easting = 500000.
false_northing = 0.
proj_params = "+proj=utm +zone=32 +north +datum=WGS84 +ellps=GRS80 +lat_0=0 +lon_0=9 +k_0=0.9996 +x_0=500000 +y_0=0 +units=m"

Then you can remap the data to your lonlat_grid:

cdo -remapnn,lonlat_grid -setgrid,gridfile_UTM32.txt O3_utm32_hour01_day01_mon01.nc outfile.nc

This works with CDO 2.4.4

RE: Remapping from UTM32 to lon-lat - Added by Lina Neunhäuserer 3 days ago

Thanks a lot! Adding the proj_params was the missing point, with them it works fine, even with cdo 1.9.10.

Best regards, Lina

RE: Remapping from UTM32 to lon-lat - Added by Uwe Schulzweida 3 days ago

You can set the proj_params attribute directly with setprojparams since CDO release 2.4.0:

cdo setprojparams,"+proj=utm +zone=32 +north +datum=WGS84 +ellps=GRS80 +lat_0=0 +lon_0=9 +k_0=0.9996 +x_0=500000 +y_0=0 +units=m" infile outfile
or
cdo -remapnn,lonlat_grid \
    -setprojparams,"+proj=utm +zone=32 +north +datum=WGS84 +ellps=GRS80 +lat_0=0 +lon_0=9 +k_0=0.9996 +x_0=500000 +y_0=0 +units=m" \
     infile outfile

RE: Remapping from UTM32 to lon-lat - Added by Karin Meier-Fleischer 3 days ago

@Uwe: Thanks for the hint

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