Hi.
It seems to me that you would want a coordinate variable with the
standard name 'realization' (whether scalar or multi-valued) and give it
an attribute with the name 'ensemble_size'. You can store the
realization number in the variable and the ensemble size in the attribute.
Grace and peace,
Jim
On 7/23/15 6:11 AM, Hedley, Mark wrote:
> I use the
> 'coordinates'
> attribute on my data variable, referencing the scalar 'ensemble_size'
> variable, thus defining this ensemble_size as a scalar coordinate
> variable for the temperature dataset
>
> mark
>
> ------------------------------------------------------------------------
> *From:* CF-metadata [cf-metadata-bounces at cgd.ucar.edu] on behalf of
> Karl Taylor [taylor13 at llnl.gov]
> *Sent:* 22 July 2015 22:53
> *Cc:* CF Metadata List
> *Subject:* Re: [CF-metadata] original_ensemble_size
>
> Hi all,
>
> I'm still curious about something:
>
> Suppose we have the temperature field stored from one member of an
> ensemble of size 10. We want to make the size of the ensemble known
> to the user. We store 10 as a scalar variable with standard name
> "ensemble_size", but how does that scalar get associated with our
> temperature variable (other than it having being stored in the same file)?
>
> cheers,
> Karl
>
> On 7/22/15 1:59 AM, Hedley, Mark wrote:
>> Hello John, Karl et al
>>
>> I'm not sure I agree with John's last statement. I think that an
>> ensemble is a defined collection of members, so my need is the need
>> for ensemble size to be defined explicitly.
>> The distinction that not all members may be present characterises the
>> need for this metadata descriptor, rather than just using the
>> dimension size of realization, which does not meet my requirement.
>>
>> On reflection, I think that I prefer Karl's name of 'ensemble_size'
>>
>> To restate my use case, I have a data set from an ensemble, where
>> there is a coordinate variable called 'realization'. Let's say there
>> are 23 members, this dimension is size 23.
>>
>> I want to reference the number of members in the ensemble, whilst
>> sub-setting the data variable in various ways.
>>
>> The suggestion is to add a scalar coordinate to my original dataset,
>> which contains the number of members in the ensemble. Then any
>> sub-setting operation will retain this coordinate, and I will always
>> be able to state that this member is member 0 of 23, 5 of 23 etc
>>
>> One requirement I have is to slice this variable, to result in a 2D
>> data array, 2 1D coordinate variables: latitude and longitude; with
>> all other coordinates as scalars.
>>
>> If it is reasonable to talk about an ensemble as a defined collection
>> of members, then I agree with Karl, that a standard_name of
>> 'ensemble_size' fits the bill. The description fits my use case nicely
>>
>> many thanks
>> mark
>>
>>
>> ------------------------------------------------------------------------
>> *From:* CF-metadata [cf-metadata-bounces at cgd.ucar.edu] on behalf of
>> John Graybeal [jbgraybeal at mindspring.com]
>> *Sent:* 22 July 2015 05:52
>> *To:* Karl Taylor
>> *Cc:* CF Metadata List
>> *Subject:* Re: [CF-metadata] original_ensemble_size
>>
>> Karl,
>>
>> To my understanding (then and now), the use case is explicitly not
>> what your definition describes. The entire point of the request was
>> to provide a label that was clearly distinguished from the typical
>> concept of ensemble size.
>>
>> John
>>
>>
>>
>> On Jul 21, 2015, at 16:36, Karl Taylor <taylor13 at llnl.gov
>> <mailto:taylor13 at llnl.gov>> wrote:
>>
>>> Dear all,
>>>
>>> I wonder if the following might also meet requirements of the use case:
>>>
>>> name: *ensemble_size*
>>> *
>>> *
>>> description: The number of member realizations in an ensemble. This
>>> name provides context for any specific realization, which might not
>>> be co-located with the other members of the ensemble.
>>>
>>> Karl
>>>
>>> On 7/20/15 9:49 PM, John Graybeal wrote:
>>>> To save others the lookup, the use case phrasing that Mark signed
>>>> on to were these words: "In my use case, the whole ensemble is not
>>>> present, I only have a subset of the members. I have a metadata
>>>> element telling me how many members there were at the time the
>>>> ensemble was created, which I would like to encode." The entire
>>>> thread is titled 'realization | x of n', but it is pretty, umm,
>>>> rich with detail.
>>>>
>>>> The last email before discussion went silent appears to be mine:
>>>>
>>>>> Modified to fit Mark's use case, I think suitable text is:
>>>>>
>>>>> name: *original_ensemble_size*
>>>>> *
>>>>> *
>>>>> description: The number of member realizations in the originally
>>>>> constituted ensemble. This provides context for any specific
>>>>> realization, for example orienting a member relative to its
>>>>> original group (even if the group is no longer intact).
>>>>>
>>>>> This does not mention forecasting, preserves the origination
>>>>> concept, and gives a bit of context, without constraining the
>>>>> application. It could even be an ensemble of observations, or cat
>>>>> videos, or ... you get the idea.
>>>>
>>>> I will let someone else provide the example of how that is
>>>> associated with the variable, it will be more authoritative!
>>>>
>>>> John
>>>>
>>>>
>>>> On Jul 20, 2015, at 14:42, Karl Taylor <taylor13 at llnl.gov
>>>> <mailto:taylor13 at llnl.gov>> wrote:
>>>>
>>>>> Hi Mark,
>>>>>
>>>>> I didn't quite understand how the standard name gets associated
>>>>> with a variable (containing 1 or more realizations from the
>>>>> ensemble). Someone said it was through a scalar coordinate
>>>>> variable, but I don't see how the ensemble member is a function of
>>>>> the ensemble size, so why would this be appropriate?
>>>>>
>>>>> Could you supply an example?
>>>>>
>>>>> Also, I didn't follow why "original" was included in "original
>>>>> ensemble size". Surely, you wouldn't report this number unless you
>>>>> thought the ensemble size was pretty much set and wouldn't
>>>>> change. In that case there shouldn't be a need for a "modified
>>>>> ensemble size", so wouldn't "ensemble size" suffice?
>>>>>
>>>>> thanks,
>>>>> Karl
>>>>>
>>>>>
>>>>> On 7/20/15 9:24 AM, Hedley, Mark wrote:
>>>>>> Hello CF
>>>>>>
>>>>>> Late last year we had a discussion about storing
>>>>>> original_ensemble_size
>>>>>> in a CF file
>>>>>> http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2014/thread.html#57756
>>>>>>
>>>>>> There were a few options discussed, with John Graybeal making the
>>>>>> suggestion
>>>>>> original_ensemble_size
>>>>>> /description: The number of members constituting an ensemble./
>>>>>> for a new standard_name definition, which seemed to fit the case
>>>>>> very well
>>>>>>
>>>>>> It does not seem to have been adopted into the standard names
>>>>>> list as yet.
>>>>>>
>>>>>> Please may this name and definition be adopted, or reasons not to
>>>>>> detailed here?
>>>>>>
>>>>>> thank you
>>>>>> mark
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> CF-metadata mailing list
>>>>>> CF-metadata at cgd.ucar.edu
>>>>>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
>>>>>
>>>>> _______________________________________________
>>>>> CF-metadata mailing list
>>>>> CF-metadata at cgd.ucar.edu <mailto:CF-metadata at cgd.ucar.edu>
>>>>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
>>>>
>>>
>>
>
>
>
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Received on Thu Jul 23 2015 - 06:11:32 BST
