Is there an accepted convention for describing the units of a climatological time axis? e.g. monthly averages January, February etc.
The CF Conventions (Section 7.4) http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.4/cf-conventions.html#climatological-statistics note the COARDS recommendation of using year ZERO: "For compatibility with COARDS, time coordinates should also be recognised as climatological if they have a units attribute of time-units relative to midnight on 1 January in year 0 i.e. since 0-1-1 in udunits syntax" But the document goes on to discourage this: "We do not recommend this convention because (a) it does not provide any information about the intervals used to compute the climatology, and (b) there is no standard for how dates since year 1 will be encoded" Looking at how others have handled this there is a tendency to choose an arbitrary base date, e.g. the World Ocean Atlas at NODC http://data.nodc.noaa.gov/thredds/dodsC/woa09/temperature_monthly_1deg.nc.html uses "days since 2008-1-1" when there is no actual relevance to year 2008 at all. All the climatologies at ERDDAP use "seconds since 1970-01-01". Thanks, John. -- John L Wilkin | [email protected] | ph: +1-609-630-0559 web: marine.rutgers.edu/~wilkin | cal: tinyurl.com/jwilkincalendar _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
