netcdf time (cf-standard) and cdo
Hello,
so a new cclm version and a new cdo seem to be incompatable.
First: Can anyone please confirm this problem?
use cdo 1.9.6 (or later) and do a “cdo info lffdYYYYMMDDHH.nc” on a file with a simulation start of
NOT
00:00:00
UTC
(and a new cclm version)
this should show the wrong time.
in our case we have an old cclm output file with:
[netcdf] time:units = “seconds since 2015-12-31 18:00:00Z“
[cdo] processes time correctly
and a new cclm (clm16) output with:
[netcdf] time:units = “seconds since 2015-12-31T18:00:00Z“
[cdo] from 1.9.6 (and later)all times shown are -18h; cdo seems to break at the T and igore the 18:00:00 / assume 00:00:00
———————
I posted it as a bug in the cdo forum, but Uwe Schulzweide said that the NetCDF CF-Standard only allows for a space between date and time.
I tried to check the CF-Standard but have not found a clear statement on this…
(Assuming someone else can confirm this incompatability) Any netcdf cf-standard experts out there? Is this a bug/old-cf-convention in cclm?
[the http://cfconventions.org/compliance-checker.html doesn´t seem to help… no errors show up for “time” even if I put in a file with “seconds since 2015-12-31ABC18:00:00Z”]
Cheers
Rolf
“seconds since 2015-12-31 18:00:00Z” follows the
ISO
8601 standard for time formatting.
https://de.wikipedia.org/wiki/ISO_8601
The CF-Conventions does not provide a mandatory format. Actually, in https://cfconventions.org/Data/cf-conventions/cf-conventions-1.8/cf-conventions.html you can find also an example that follows the
ISO
8601 standard:
Example 5.7. Lambert conformal projection
time:units = “hours since 2004-06-23T22:00:00Z”;
Therefore it is a problem in
CDO
.
Since we start climate simulations generally at 00UTC, this does not harm.
If you really want to start at 18
UTC
, the only work around is to replace the T by a blank in netcdf_io.f90 at about line 1900 and create a new executable.
“seconds since 2015-12-31 18:00:00Z” follows the ISO 8601 standard for time formatting.
https://de.wikipedia.org/wiki/ISO_8601The CF-Conventions does not provide a mandatory format. Actually, in https://cfconventions.org/Data/cf-conventions/cf-conventions-1.8/cf-conventions.html you can find also an example that follows the ISO 8601 standard:
Example 5.7. Lambert conformal projection time:units = “hours since 2004-06-23T22:00:00Z”;Therefore it is a problem in CDO .
Since we start climate simulations generally at 00UTC, this does not harm.
If you really want to start at 18 UTC , the only work around is to replace the T by a blank in netcdf_io.f90 at about line 1900 and create a new executable.
“seconds since 2015-12-31 18:00:00Z” follows the
ISO
8601 standard for time formatting.
https://de.wikipedia.org/wiki/ISO_8601
The CF-Conventions does not provide a mandatory format. Actually, in https://cfconventions.org/Data/cf-conventions/cf-conventions-1.8/cf-conventions.html you can find also an example that follows the
ISO
8601 standard:
Example 5.7. Lambert conformal projection
time:units = “hours since 2004-06-23T22:00:00Z”;
Therefore it is a problem in
CDO
.
Since we start climate simulations generally at 00UTC, this does not harm.
If you really want to start at 18
UTC
, the only work around is to replace the T by a blank in netcdf_io.f90 at about line 1900 and create a new executable.
Hello,
so a new cclm version and a new cdo seem to be incompatable.
First: Can anyone please confirm this problem?
use cdo 1.9.6 (or later) and do a “cdo info lffdYYYYMMDDHH.nc” on a file with a simulation start of NOT 00:00:00 UTC (and a new cclm version)
this should show the wrong time.
in our case we have an old cclm output file with:
[netcdf] time:units = “seconds since 2015-12-31 18:00:00Z“
[cdo] processes time correctly
and a new cclm (clm16) output with:
[netcdf] time:units = “seconds since 2015-12-31T18:00:00Z“
[cdo] from 1.9.6 (and later)all times shown are -18h; cdo seems to break at the T and igore the 18:00:00 / assume 00:00:00
———————
I posted it as a bug in the cdo forum, but Uwe Schulzweide said that the NetCDF CF-Standard only allows for a space between date and time.
I tried to check the CF-Standard but have not found a clear statement on this…
(Assuming someone else can confirm this incompatability) Any netcdf cf-standard experts out there? Is this a bug/old-cf-convention in cclm?
[the http://cfconventions.org/compliance-checker.html doesn´t seem to help… no errors show up for “time” even if I put in a file with “seconds since 2015-12-31ABC18:00:00Z”]
Cheers
Rolf