"cdo remapbil" command leads to missing values.

When I try to change the horizontal resolution, I get the error of missing values near the South Pole. Although 'org.nc' file does not contain any missing value, the newly generated 'new.nc' file does.

cdo remapbil,r480x241 -selname,ht org.nc new.nc

Thanks,

Junsu

Here is the cdo environment of mine.
---
jkim@ngate6% cdo --version
Climate Data Operators version 1.8.1rc1 (http://mpimet.mpg.de/cdo)
Compiled: by jkim on ngate6 (x86_64-unknown-linux-gnu) Mar 28 2017 06:25:53
Compiler: gcc -std=gnu99 -fPIC -fopenmp
version: gcc (GCC) 4.9.2 20141030 (Cray Inc.)
Features: DATA PTHREADS OpenMP4 HDF5 NC4/HDF5/threadsafe SZ UDUNITS2 PROJ.4 SSE2
Libraries: HDF5/1.8.14(1.8.13) proj/4.92
Filetypes: srv ext ieg grb1 grb2 nc1 nc2 nc4 nc4c
CDI library version : 1.8.1 of Mar 28 2017 06:25:00
CGRIBEX library version : 1.7.6 of Dec 20 2016 19:55:24
GRIB_API library version : 1.12.3
NetCDF library version : 4.3.2 of Mar 13 2015 07:43:45 $
HDF5 library version : 1.8.13 threadsafe
SERVICE library version : 1.4.0 of Mar 28 2017 06:24:53
EXTRA library version : 1.4.0 of Mar 28 2017 06:24:49
IEG library version : 1.4.0 of Mar 28 2017 06:24:51
FILE library version : 1.8.2 of Mar 28 2017 06:24:49

Download all files

new.nc (459 KB) new.nc
org.nc (6.76 MB) org.nc

Replies (4)

RE: "cdo remapbil" command leads to missing values. - Added by Ralf Mueller about 7 years ago

I can find missing values in org.nc. here is a plot of your data

% cdo remapbil,r480x241 -selname,ht org.nc new.nc                                                                                                                                         [Fri 2017-03-31|10:45:12]
cdo remapbil: Started child process "selname,ht org.nc (pipe1.1)".
cdo remapbil: SCRIP bilinear weights from lonlat (1536x1152) to lonlat (480x241) grid, with source mask (1762142)
cdo(2) selname: Processed 1769472 values from 1 variable over 1 timestep ( 0.17s )
cdo remapbil: Processed 1769472 values from 1 variable over 1 timestep ( 0.17s )
<ram@luthien:~/Downloads>
% cdo infov org.nc                                                                                                                                                                        [Fri 2017-03-31|10:45:14]
    -1 :       Date     Time   Level Gridsize    Miss :     Minimum        Mean     Maximum : Parameter name
     1 : 2016-07-07 00:00:00     500  1769472    7330 :      4838.0      5578.9      5966.0 : ht            
cdo infon: Processed 1769472 values from 1 variable over 1 timestep ( 0.02s )
<ram@luthien:~/Downloads>
% cdo infov new.nc                                                                                                                                                                        [Fri 2017-03-31|10:45:25]
    -1 :       Date     Time   Level Gridsize    Miss :     Minimum        Mean     Maximum : Parameter name
     1 : 2016-07-07 00:00:00     500   115680     506 :      4838.0      5577.5      5966.0 : ht            
cdo infon: Processed 115680 values from 1 variable over 1 timestep ( 0.00s )

I use cdo-1.8.0. IMO it's reasonable to have missing values in the output:

Download all files

ht-in-org.png (436 KB) ht-in-org.png
ht-in-new.png (435 KB) ht-in-new.png

RE: "cdo remapbil" command leads to missing values. - Added by Junsu Kim about 7 years ago

Hello Ralf, thank you for the work.

When I looked into the org.nc file with ncview, I could not find any missing value. Attached image file was what I saw before.

Junsu

capture.PNG (165 KB) capture.PNG

RE: "cdo remapbil" command leads to missing values. - Added by Ralf Mueller about 7 years ago

it looks the same with ncview on my machine. I usually use cdo for it

<ram@luthien:~/Downloads>
% cdo infov org.nc
    -1 :       Date     Time   Level Gridsize    Miss :     Minimum        Mean     Maximum : Parameter name
     1 : 2016-07-07 00:00:00     500  1769472    7330 :      4838.0      5578.9      5966.0 : ht            
cdo infon: Processed 1769472 values from 1 variable over 1 timestep ( 0.01s )
<ram@luthien:~/Downloads>

The point is: There are location with values outside the valid range. your variable ht has the attributes

                ht:valid_min = 4838.f ;
                ht:valid_max = 5970.f ;

but the overall minimum is 4829.0. Panoply (and CDO) seem to respect this CF-attribute while ncview only reacts on the _FillValue or missing_value attribute.

RE: "cdo remapbil" command leads to missing values. - Added by Junsu Kim about 7 years ago

I see your point. Thank you for the kind explanation. Junsu

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