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 <Chris.Barker at noaa.gov>
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
>
> Chris.Barker at noaa.gov
> _______________________________________________
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>
--
Dr. M. Benno Blumenthal benno at iri.columbia.edu
International Research Institute for climate and society
The Earth Institute at Columbia University
Lamont Campus, Palisades NY 10964-8000 (845) 680-4450
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