[CF-metadata] various "time" in CF
Hi Antonio,
thank you for your detailed answer. You answered some of my questions but completely misses one crucial point, i.e. how do I distinguish 2 very different usage of the same generic standard name ?
I give you few concrete examples.
Example 1:
dimensions:
i = 360 ;
j = 180 ;
t = 1 ;
variables:
double time(t) ;
time:units = "hours since 2010-01-01 00:00:00" ;
time:standard_name = "time" ;
time:calendar = "gregorian" ;
time:axis = "T" ;
.... lat/long here ....
float data(t, j, i) ;
...
data:standard_name = "temperature" ;
data:coordinates = "time lat lon" ;
...
data:
time = [ 00 ]
...
What is this? Is this an analysis? an observation? or something else?
Example 2:
dimensions:
i = 360 ;
j = 180 ;
t = 5 ;
variables:
double forecast_reference_time(t) ;
forecast_reference_time:units = "hours since 2010-01-01 00:00:00" ;
forecast_reference_time:standard_name = "forecast_reference_time" ;
double leadtime(t) ;
leadtime:units="hours" ;
leadtime:standard_name="forecast_period" ;
.... lat/long ....
float data(t, j, i) ;
...
data:standard_name = "temperature" ;
data:coordinates = "leadtime forecast_reference_time lat lon" ;
...
data:
forecast_reference_time = [ 00, 00, 00, 00, 00 ]
leadtime = [ 00, 06, 12, 18, 24 ]
...
What is this? is it the forecast done back on the 1st January 2010? or is it a hindcast done years later to test the model of today? or is it a forecast from a reanalysis dataset, for instance ERA5? or something else?
extra question for example 2: lets assume it is a hindcast. how will I be able to distinguish this hindcast done today from the hindcast I am going to do in 5 years time to test the model then? or from the hindcast I did 2 years ago for that date?
It is to clarify this sort of things that I would like to have extra standard name, something less generic than the 3 available standard names.
If I change the standard name in example 1 for "analysis_time", isn't it more clear what it is?
If I use hindcast_reference_time and hindcast_period in example 2 AND I include a mechanism to encode when the hindcast has been computed, isn't it clearer as well?
more comments are very welcome! :)
cheers,
/S?bastien
Received on Wed Oct 18 2017 - 10:19:03 BST
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