Hi all -
I'm finally catching up with this discussion, after being at sea for the
past
month. I have to agree with Seth McGinnis; I vote no.
We're happy with the CF terms and their definitions. The last sentence
in the
definition of surface_downwelling_shortwave_flux_in_air (and probably
some of
the other flux terms) states:
In accordance with common usage in geophysical disciplines, "flux"
implies per
unit area, called "flux density" in physics.
This seems perfectly clear. If flux_density is technically more correct,
so be it; the
canonical units and the definitions clarify the meaning. We could make
*lots* of standard
names longer and more technically complete; in reading through the
threads on this
request, I just haven't seen a clear explanation of why the existing
flux terms now
need to change.
Cheers - Nan
On 5/19/15 6:25 PM, Seth McGinnis wrote:
> I vote no.
>
> As mentioned, using "flux" to refer to what is technically "flux
> density" is commonplace and normal in many geoscience fields, and it's
> clear by the lack of questions about it that this does not cause
> problems for users.
>
> Deprecating names and replacing them with an alias creates the
> opportunity for confusion, and given the number and popularity of the
> names that would be affected, I think this change would create a great
> deal of confusion. A reasonable alternative solution
> ("integrated_flux") has been suggested for handling "proper" fluxes, and
> as Karl says, we'd likely want to use that even if we did make the
> change to avoid confusion with the old names.
>
> So it seems to me that there's no real benefit to changing flux to
> flux_density, and the potential for a very large downside.
>
> Cheers,
>
> --Seth McGinnis
>
> On 5/19/15 3:23 PM, Jonathan Gregory wrote:
>> Dear all
>>
>> Like Karl, I thought that many people would have opinions, but so far there
>> are none. Please express your views! Shall we rename flux quantities in units
>> of something per m2 to flux_density in all existing standard names? Here are
>> the kinds of flux [density] we name:
>>
>> carbon energy evaporation graupel heat longwave mass melt mole momentum
>> photon precipitation radiative rainfall refreezing runoff salt shortwave
>> snowfall sublimation throughfall transpiration water_vapor water
>>
>> With regard to your point, Karl, I think we would not use plain "flux" in the
>> area-integral sense. We would avoid using it altogether. We already have ways
>> of working round it e.g. northward heat transport in W and there is no need
>> to change those names.
>>
>> Best wishes and thanks
>>
>> Jonathan
>>
>> ----- Forwarded message from Karl Taylor <taylor13 at llnl.gov-----
>>
>> Date: Thu, 14 May 2015 10:47:55 -0700
>> From: Karl Taylor <taylor13 at llnl.gov>
>> To: cf-metadata at cgd.ucar.edu
>> Subject: Re: [CF-metadata] flux
>> User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:31.0)
>> Gecko/20100101 Thunderbird/31.6.0
>>
>> Dear Jonathan,
>>
>> My oh my, this is bound to generate lots of opinions. I do recall
>> the original discussion conclusion that although "flux density" was
>> the proper name, we'd be lax in this case and go with common usage,
>> "flux". An argument against the common usage is that if we want to
>> define the flux density integrated over some surface, then we
>> couldn't call it "flux", which is what it is. Perhaps to
>> distinguish this from "flux" (W m-2), we would call this
>> "integrated_flux" (W). Do we have examples of having to do this
>> kind of thing in the current standard names?
>>
>> Even if we rename "flux" "flux density", we probably wouldn't want
>> to refer to the integrated flux as simply "flux" because so many
>> fields have already been written named "flux" when "flux density"
>> was meant.
>>
>> It's not going to be easy.
>>
>> Karl
>>
>> On 5/14/15 9:37 AM, Jonathan Gregory wrote:
>>> Dear all
>>>
>>> In connection with the radiative flux from the sun, the question has come up
>>> of whether we should use the phrase flux_density for a flux per unit area in
>>> all the standard names which currently have the word "flux". This would be
>>> correct in physical terminology, but years ago we chose to use "flux" because
>>> it's the normal terminology in many geosciences. There are more than 200
>>> standard names of "flux" - radiative fluxes, mass fluxes and mole fluxes. In
>>> some of them I don't think "flux density" is ever used e.g. I have never
>>> heard of an "ocean flux density adjustment", and Google finds one hit for
>>> "snowfall flux density". However we could rename them all and establish aliases
>>> to the present names, if that would be an advantage for users of standard
>>> names. Should this be done?
>>>
>>> Cheers
>>>
>>> Jonathan
>>>
--
*******************************************************
* 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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