CDO

Hi Sandro,

you can write a shell script and loop through time. Here is an example which extracts level 50, subtracts the fields of the timesteps n and n-1, and merge the temporary files to the output file outfile_daily_values_totprec_201710_075.nc.

#!/bin/ksh

#-- de-compute the single daily values of variable tp from cumulative data

infile=totprec_201710_075.nc
outfile=outfile_daily_values_totprec_201710_075.nc

#-- use -b 32 because tp is of type short

cdo -b 32 -select,level=50 $infile tmp_50.nc

#-- save first timestep

cdo -seltimestep,1 tmp_50.nc tmp_N_1.nc

#-- loop through the timestep and subtract field1 from field 2

for j in $(seq 2 215)
do
   i=$(expr $j - 1)
   cdo -seltimestep,$i tmp_50.nc tmp_$i.nc
   cdo -seltimestep,$j tmp_50.nc tmp_$j.nc
   cdo -sub tmp_$j.nc tmp_$i.nc tmp_N_$j.nc
done

cdo -O mergetime tmp_N_*.nc $outfile
rm -rf tmp_N_*.nc

exit

-Karin

Thank you Karin.

I was trying with a set of instructions using shift time.
It seems to work nicely.
Thanks for helping!

#Shift time axis and remove the first record
   cdo -delete,timestep=1 -shifttime,-1day $FILEIN $WDIR/${BASENAME}_B.nc

#Remove the last record
   cdo -delete,timestep=-1 $FILEIN $WDIR/${BASENAME}_A.nc

#Store the cumulated during first day in a separate file
   cdo -b 32 -shifttime,-1day -seltimestep,1 $FILEIN $WDIR/${BASENAME}_A1.nc

#Compute daily cumulated
   cdo -b 32 -sub $WDIR/${BASENAME}_B.nc $WDIR/${BASENAME}_A.nc ${WDIR}/${BASENAME}_C.nc

#Merge back the first day
   cdo -O -mergetime $WDIR/${BASENAME}_A1.nc ${WDIR}/${BASENAME}_C.nc ${WDIR}/${BASENAME}.nc

please checkout the operator deltat. it;s not documented, but computes differences between consecutive timesteps

hth
ralf

Thank you Ralf, this is what we where looking for.

Best!

S.

Ralf Mueller wrote:

please checkout the operator deltat. it;s not documented, but computes differences between consecutive timesteps

hth
ralf

Hi Ralf,

Thanks for you help, the operator deltat worked in a computer with the last version of Ubuntu (18.04), but in mine, which version is 16.04 the operator deltat doesn't work, and I see that the cdo version is 1.7.0. When I tried to upgrate to the last version, nothing happens, it stills in 1.7.0. So, this is due to the version of Ubuntu?? or there is another thing that I can do to upgrate cdo and use the operator?

Kind regards,

Silvana

Hi Silvana!

the debian package for the debian-based distros is usually outdated because of the long release cycle of debian.

Anaconda is an easy option to install cdo on your own. does this work for you?

hth
ralf