[CF-metadata] various "time" in CF

Sebastien Villaume sebastien.villaume at ecmwf.int
Wed Oct 18 08:03:57 MDT 2017

Hi all,

I am trying to find a consistent way to describe Time in CF-netCDF, so far without success. :(

The main reason is that there are only 3 standard names to describe Time (unless I missed something in the official CF standard name list):

 - time
 - forecast_reference_time
 - forecast_period

I would like to describe properly (and without relying at all on the file names):
 - a forecast
 - several forecasts in the same file
 - an analysis
 - several analyses in the same file
 - a reforecast/hindcast
 - several reforecasts/hindcasts in the same file
 - observations
 - data assimilation/acquisition 
 - distinguish if the data variable is associated with an analysis time or a forecast reference time (some data variables do differ between analysis and forecast step 0!)
 - etc.

of course, I could use the generic "time" standard name and put all the required informations in the "long_name" attribute but I don't want to do that: long_name is a free text attribute, I need controlled vocabulary which is exactly the purpose of the standard_name attribute. 

I also need to be able to reference these "kinds" of time coordinates in the cell_method attribute of my data variables to describe statistical processing like sums/accumulations, min/max, means, standard deviations, etc. 

The simplest solution that comes to my mind would be to add new standard names for these kinds of time coordinates but it seems to be such a common issue that I can't believe nobody proposed before. Hence, I am wondering if I am missing something here or if someone tried and it was not very well received/rejected...  

Is it worth spending time drafting a proposal to define new standard names for time coordinates?


Dr. Sébastien Villaume

M.A.R.S administrator
DATA Governance facilitator

Shinfield Park,
Reading RG2 9AX, UK
+44 7825 521592
sebastien.villaume at ecmwf.int

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