Dear Nan and Lars
What I said is what I've understood this name to mean, since I wrote it in the
first edition of the standard name table. However, unfortunately we have never
defined what we mean by "precipitation"! I believe it means water which falls
at the time specified or during the time interval specified, not the water
which has previously fallen.
If it is a total since the last time the gauge was emptied, as Lars suggests,
you could still use this name, if you specified a time interval which begins
when the gauge reads zero. That would be the same for all of the later times of
measurement until it is next emptied, so each of these time intervals would
overlap, each one being longer than the one before. That's fine, though - it's
OK for cell bounds to overlap.
Best wishes
Jonathan
----- Forwarded message from B?rring Lars <Lars.Barring at smhi.se> -----
> Date: Thu, 24 Jan 2019 20:36:58 +0000
> From: B?rring Lars <Lars.Barring at smhi.se>
> To: "ngalbraith at whoi.edu" <ngalbraith at whoi.edu>, "cf-metadata at cgd.ucar.edu"
> <cf-metadata at cgd.ucar.edu>
> Subject: Re: [CF-metadata] Two [simple] questions
>
> Nan ---
>
> Just to better understand your setup: the data you are referring to comes from a totalizer rain gauge, where the data may look like
>
> day i, 321 mm
> day j, 321 mm
> day k, 333 mm
> day l, 333 mm
> day k, 399 mm
>
> and this is what you record , and store?
>
> /Lars
>
> ________________________________________
> Fr?n: CF-metadata [cf-metadata-bounces at cgd.ucar.edu] för Nan Galbraith [ngalbraith at whoi.edu]
> Skickat: den 24 januari 2019 19:42
> Till: cf-metadata at cgd.ucar.edu
> ?mne: Re: [CF-metadata] Two [simple] questions
>
> I sincerely hope you're wrong about these standard names, Jonathan!
>
> We include precip in our met files, and use the
> lwe_thickness_of_precipitation_amount
> standard name to report the actual level of water in a rain gauge.
>
> It is NOT a rate of precip, which is calculated (roughly, for rain
> gauges) by a first difference.
>
> If the values in this variable were interpreted as a rate, it would be
> completely incorrect; values
> that are unchanging convert to a rate of 0, no matter how high they may be.
>
> Maybe I've been mis-using this standard name?
>
> Thanks - Nan
>
>
>
>
> On 1/24/19 9:34 AM, Jonathan Gregory wrote:
> > Dear Lars
> >
> >> 1. If I have (observed) daily precipitation with unit mm/day and want to store this in a CF compliant file, should I use standard name
> >> --- "lwe_thickness_of_precipitation_amount" with canonical unit metre and the "per day" part is inferred from the time bounds, or
> >> --- "lwe_precipitation_rate" having canonical unit "m s-1",
> >> --- if both are acceptable, is one to be preferred?
> > You can use whichever you prefer. They would also be distinguished by
> > cell_methods. The first is extensive in time, so it has cell_methods of sum,
> > the second is intensive and has cell_methods of mean.
> >
> >> 2. The long_name is free, but should be descriptive. I am thinking of this as a succinct plot title, so the question is what practical limitation there might be in relation to different software. Is it advisable to use ASCII spaces (from
> >> Github issue #141 indicates that only standard ASCII character set should be used) ?
> > I expect others have something useful to say about that.
> >
> > Best wishes
> >
> > Jonathan
> > _______________________________________________
> > CF-metadata mailing list
> > CF-metadata at cgd.ucar.edu
> > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
> >
>
>
> --
> *******************************************************
> * Nan Galbraith Information Systems Specialist *
> * Upper Ocean Processes Group Mail Stop 29 *
> * Woods Hole Oceanographic Institution *
> * Woods Hole, MA 02543 (508) 289-2444 *
> *******************************************************
>
>
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----- End forwarded message -----
Received on Thu Jan 24 2019 - 15:09:45 GMT
