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how to change time format in a nc file e.g. 1981-01-01 to 1981-01-01 00:00 -1981-01-01 23:00

Added by Subhra Sekhar Maity 6 months ago

Hi everyone
I have a nc file with 13879 daily time steps starting from 1981-01-01. I want to convert the time steps to 1981-01-01 00:00-1981-01-01 23:00 format. How to do that with cdo? I am attaching two nc files one of which needs this conversion and other one contains the required time steps.
The one which required conversion is named as
1) imd_pr_1981_2018_clipped.nc

The other one which is in correct format is

2) pr_1981_2018_clipped_mm.nc

Please help me converting the time steps as stated above

Data.rar (140 MB) Data.rar

Replies (5)

RE: how to change time format in a nc file e.g. 1981-01-01 to 1981-01-01 00:00 -1981-01-01 23:00 - Added by Subhra Sekhar Maity 6 months ago

I want to correct my question. My question is how should I incorporate the time_bnds in the nc file?

RE: how to change time format in a nc file e.g. 1981-01-01 to 1981-01-01 00:00 -1981-01-01 23:00 - Added by Karin Meier-Fleischer 6 months ago

If you want to change the time values then you can use CDO settaxis to set the time from 00:00:00 to 12:00:00. This won't change the variable data.

Set time to same time values as in pr_1981_2018_clipped_mm.nc:

cdo -setreftime,1900-01-01,00:00:00,1day \
    -settaxis,1981-01-01,12:00:00,1day \
     imd_pr_1981_2018_clipped.nc tmp.nc

Generate the time bounds and add it to the file with NCO's ncap2 routine:

ncap2 -O -s 'defdim("bnds",2);time_bnds=make_bounds(TIME,$bnds,"time_bnds");' \
         tmp.nc imd_pr_1981_2018_clipped_changed.nc

Btw, for the first time step in imd_pr_1981_2018_clipped.nc all values of the variable RAINFALL are 0.

RE: how to change time format in a nc file e.g. 1981-01-01 to 1981-01-01 00:00 -1981-01-01 23:00 - Added by Subhra Sekhar Maity 6 months ago

Thank you very much Sir for the answer. It worked. Can you please suggest me from where I can learn such codes for CDO and NCO?

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