CDO

Hi Felix,

I tried to reproduce the problem but if I use a 0.5 degree grid as input and remap it to a 0.05 degree grid the values are ok.

Generate a 0.5 degrees file using the topo operator and remapbil

cdo -f nc -remapbil,r720x360 -topo topo_720x360.nc

 lon = 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 
    8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 
    16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5, 20, 20.5, 21, 21.5, 22, 22.5, 23, 
    23.5, 24, 24.5, 25, 25.5, 26, 26.5, 27, 27.5, 28, 28.5, 29, 29.5, 30, 
    30.5, 31, 31.5, 32, 32.5, 33, 33.5, 34, 34.5, 35, 35.5, 36, 36.5, 37, 
    37.5, 38, 38.5, 39, 39.5, 40, 40.5, 41, 41.5, 42, 42.5, 43, 43.5, 44, 
    44.5, 45, 45.5, 46, 46.5, 47, 47.5, 48, 48.5, 49, 49.5, 50, 50.5, 51, 
    51.5, 52, 52.5, 53, 53.5, 54, 54.5, 55, 55.5, 56, 56.5, 57, 57.5, 58, 
...

cdo -f nc -remapycon,r7200x3600 topo_720x360.nc topo_7200x3600.nc

 lon = 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 
    0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 1.05, 1.1, 1.15, 1.2, 1.25, 
    1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 
    1.95, 2, 2.05, 2.1, 2.15, 2.2, 2.25, 2.3, 2.35, 2.4, 2.45, 2.5, 2.55, 
    2.6, 2.65, 2.7, 2.75, 2.8, 2.85, 2.9, 2.95, 3, 3.05, 3.1, 3.15, 3.2, 
    3.25, 3.3, 3.35, 3.4, 3.45, 3.5, 3.55, 3.6, 3.65, 3.7, 3.75, 3.8, 3.85, 
    3.9, 3.95, 4, 4.05, 4.1, 4.15, 4.2, 4.25, 4.3, 4.35, 4.4, 4.45, 4.5, 
    4.55, 4.6, 4.65, 4.7, 4.75, 4.8, 4.85, 4.9, 4.95, 5, 5.05, 5.1, 5.15, 
    5.2, 5.25, 5.3, 5.35, 5.4, 5.45, 5.5, 5.55, 5.6, 5.65, 5.7, 5.75, 5.8, 
    5.85, 5.9, 5.95, 6, 6.05, 6.1, 6.15, 6.2, 6.25, 6.3, 6.35, 6.4, 6.45, 
    6.5, 6.55, 6.6, 6.65, 6.7, 6.75, 6.8, 6.85, 6.9, 6.95, 7, 7.05, 7.1, 
    7.15, 7.2, 7.25, 7.3, 7.35, 7.4, 7.45, 7.5, 7.55, 7.6, 7.65, 7.7, 7.75, 
...

-Karin

Hi Karin, see the lonlat description file attached. The 0.5° grid looks the same, but - as said - with 0.5° differences.

The grid description is not enough, please, upload the input data file and the CDO call you use for remapping.

Okay, here are the data, the command used was:

`cdo -z zip_9 -P 6 remapycon,r3.grid hoaps-g.r30.d01.wvpa.2011-07-01.nc hoaps-g.r3.d01.wvpa.2011-07-01.nc`

The default number of significant digits for double precision floats in ncdump is 15.
That means you will see only the first 15 significant digits in the output of ncdump.
If you increase this number to e.g. 20, you will see that nearly all values are not exact because most floating point number can't be represented exactly.
You have to decrease the number of significant digits to e.g. 9 if you want to see only 9 digits:

ncdump -v lat,lon -p 7,9  infile

great post. thnank