Hi Benno, Jonathan, Chris, Would you mind if I forward your email exchange to the MetOceans Domain Working Group of the OGC? They are grappling with similar time issues, but I don't think they have considered the relationship to trajectories that Benno has raised.
-- Ben On Tue, May 17, 2011 at 12:33 PM, Benno Blumenthal <[email protected]>wrote: > I think what Jonathan said > > > Therefore I think it would be sensible to add some more general names which >> you could use, such as reference_time and elapsed_time. You might say that >> a "time" is expressed by udunits as an elapsed_time since a >> reference_time. >> > > > is pretty much on the mark: I was using the word "period" because the > standard_name's grammar suggests using period for a time interval and saving > "time" for temporal with reference time, though "elapsed_period" sounds a > bit strange to my ears. > > As for my using "forecast_reference_time", I am willing to accept the > judgement that it is not what I want, but I can't say that it is all that > clear. Forecasts are integrations from initial conditions a.k.a the > analysis, which is precisely what happens in a trajectory -- the terms used > in defining forecast_reference_time are mostly ill-defined, particularly > what is the "time of the analysis" -- in practice it is the sampling time of > the most recent data in the forecast, plus the processing time it takes to > get the data to the forecast, which means essentially that the forecaster > gets to define it -- it does not have an absolute (standardized) meaning. > > Benno > > > On Tue, May 17, 2011 at 12:31 PM, Christopher Barker < > [email protected]> wrote: > > On 5/17/11 9:17 AM, Jonathan Gregory wrote: > >> > >> Dear Benno > >> > >>> CF has standard names forecast_reference_time, forecast_period and > >>> time which are interrelated in a particular way. > >>> > > > > note, from the standard name table: > > > > """ > > The forecast reference time in NWP is the "data time", the time of the > > analysis from which the forecast was made. It is not the time for which > the > > forecast is valid; the standard name of time should be used for that > time. > > """ > > > > So this really is a concept specific to forecasts, and not at all what > you > > want. Similarly for forecast_period. > > > >>> I have a trajectory dataset which also has reference_time, period, > >>> and time which are interrelated in the same way, but forecast is not > >>> an appropriate descriptor: > > > > I think you have the really standard time here, usually simply the "time" > > array (expressed in time-since-a-reference-datetime). What does "period" > > mean in your case? > > > > -Chris > > > > > > -- > > Christopher Barker, Ph.D. > > Oceanographer > > > > Emergency Response Division > > NOAA/NOS/OR&R (206) 526-6959 voice > > 7600 Sand Point Way NE (206) 526-6329 fax > > Seattle, WA 98115 (206) 526-6317 main reception > > > > [email protected] > > _______________________________________________ > > CF-metadata mailing list > > [email protected] > > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > > > > > > -- > Dr. M. Benno Blumenthal [email protected] > International Research Institute for climate and society > The Earth Institute at Columbia University > Lamont Campus, Palisades NY 10964-8000 (845) 680-4450 > > > _______________________________________________ > CF-metadata mailing list > [email protected] > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > >
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