observing -32767 values after remaping

Good day,

I used the remabil function to regrid a 90th percentile temp file derived from ERA5 temperature data from its native resolution to 0.5,1, and 2.5 degrees resolution and I noticed the -32767 values on some specific lon/lat throughout the time-series. Is this a bug or an error from my side? the version of my cdo is 1.9.4. I used the code remapbil,0.5grid.txt for the 0.5 degrees. I used this area sellonlatbox,4.4,12.08,8.34,12.7 to create the template.nc file for the remap. attached is my 90thtemp file, and the 3 .txt files and a sample of the error I observed.
thank you for you time.

Download all files

temp90thdegC-daily_ERA5_with_timesteps1981-2010.nc (25 MB) temp90thdegC-daily_ERA5_with_timesteps1981-2010.nc	90th percentile temp file
2.5by2.5_grid.txt (270 Bytes) 2.5by2.5_grid.txt	2.5 grid file
1by1_grid.txt (267 Bytes) 1by1_grid.txt	1.0 grid.txt
0.5grid.txt (275 Bytes) 0.5grid.txt	0.5.txt
temp90th-timeseries-remap100.txt (11.5 MB) temp90th-timeseries-remap100.txt	output.txt sample error

Replies (2)

RE: observing -32767 values after remaping - Added by Karin Meier-Fleischer over 3 years ago

Hi Idris,

its not a bug. The value -32767 is the _FillValue (missing value) of the variable t2m.

ncdump -h temp90thdegC-daily_ERA5_with_timesteps1981-2010.nc

netcdf temp90thdegC-daily_ERA5_with_timesteps1981-2010 {
dimensions:
    time = UNLIMITED ; // (10950 currently)
    bnds = 2 ;
    longitude = 37 ;
    latitude = 16 ;
variables:
    double time(time) ;
        time:standard_name = "time" ;
        time:long_name = "time" ;
        time:bounds = "time_bnds" ;
        time:units = "hours since 1900-01-01 00:00:00.0" ;
        time:calendar = "365_day" ;
        time:axis = "T" ;
    double time_bnds(time, bnds) ;
    float longitude(longitude) ;
        longitude:standard_name = "longitude" ;
        longitude:long_name = "longitude" ;
        longitude:units = "degrees_east" ;
        longitude:axis = "X" ;
    float latitude(latitude) ;
        latitude:standard_name = "latitude" ;
        latitude:long_name = "latitude" ;
        latitude:units = "degrees_north" ;
        latitude:axis = "Y" ;
    float t2m(time, latitude, longitude) ;
        t2m:long_name = "2 metre temperature" ;
        t2m:units = "K" ;
        t2m:_FillValue = -32767.f ;
        t2m:missing_value = -32767.f ;

cdo sinfon temp90thdegC-daily_ERA5_with_timesteps1981-2010.nc
   File format : NetCDF2
    -1 : Institut Source   T Steptype Levels Num    Points Num Dtype : Parameter name
     1 : unknown  unknown  v instant       1   1       592   1  F32  : t2m           
   Grid coordinates :
     1 : lonlat                   : points=592 (37x16)
                        longitude : 4 to 13 by 0.25 degrees_east
                         latitude : 13.25 to 9.5 by -0.25 degrees_north
   Vertical coordinates :
     1 : surface                  : levels=1
   Time coordinate :  10950 steps
     RefTime =  1900-01-01 00:00:00  Units = hours  Calendar = 365_day  Bounds = true
  YYYY-MM-DD hh:mm:ss  YYYY-MM-DD hh:mm:ss  YYYY-MM-DD hh:mm:ss  YYYY-MM-DD hh:mm:ss
  1981-01-01 11:30:00  1981-01-02 11:30:00  1981-01-03 11:30:00  1981-01-04 11:30:00
  1981-01-05 11:30:00  1981-01-06 11:30:00  1981-01-07 11:30:00  1981-01-08 11:30:00
  1981-01-09 11:30:00  1981-01-10 11:30:00  1981-01-11 11:30:00  1981-01-12 11:30:00
  ...

The minimum latitude is 9.5 while the grid descriptor files start already at minimum latitude 8.5 respectively 8.75. Exactly for this reason you get missing values when you do remap.

-Karin

compare.png (155 KB) compare.png

RE: observing -32767 values after remaping - Added by Idris Wada over 3 years ago

thank you foryour response, i really appraciate.

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