Hi Jonathan,
I had objected to mass_fraction earlier, but if it is immediately
followed, for example, by "of_rainfall" it won't get confused with the
mass_fraction used to describe a single species in a mixture.
I don't like "amount" because although it is a ratio, I think it
normally describes an extensive quantity, and the fractions we want to
report could be instantaneous.? I suppose rainfall_flux or rainfall_rate
would also be o.k.
Your suggestion to start with, for example, "mass_fraction_of_rainfall
..." would also be o.k. with me.
best regards,
Karl
On 6/25/18 6:38 AM, Jonathan Gregory wrote:
> Dear Alison et al.
>
> I still find myself tripping over rainfall_mass. Why not rainfall_amount,
> rainfall_flux or rainfall_rate? They would all be the same number, since it's
> a *fraction*. Another possibility would be a reordering to
> mass_fraction_of_rainfall_falling_onto_surface_snow (1)
> mass_fraction_of_solid_precipitation_falling_onto_surface_snow (1)
> We have many mass_fraction names, and consistency could be good.
>
> Best wishes
>
> Jonathan
>
> ----- Forwarded message from Alison Pamment - UKRI STFC <alison.pamment at stfc.ac.uk> -----
>
>> Date: Thu, 21 Jun 2018 11:34:45 +0000
>> From: Alison Pamment - UKRI STFC <alison.pamment at stfc.ac.uk>
>> To: 'Karl Taylor' <taylor13 at llnl.gov>, Martin Juckes - UKRI STFC
>> <martin.juckes at stfc.ac.uk>, "CF-metadata (cf-metadata at cgd.ucar.edu)"
>> <cf-metadata at cgd.ucar.edu>
>> Subject: Re: [CF-metadata] Precipitation fractions for LS3MIP
>>
>> Dear Martin, Jonathan, Karl,
>>
>> I have had another look at these two names and amended the definitions in the light of the discussion.
>>
>> fraction_of_rainfall_mass_falling_onto_surface_snow (1)
>> 'The quantity with standard name fraction_of_rainfall_mass_falling_onto_surface_snow is the mass of rainfall falling onto snow as a fraction of the mass of rainfall falling within the area of interest. The horizontal domain over which the quantity is calculated is described by the associated coordinate variables and coordinate bounds or by a coordinate variable or scalar coordinate variable with the standard name of "region" supplied according to section 6.1.1 of the CF conventions. The phrase "surface_snow" means snow lying on the surface.'
>>
>> fraction_of_solid_precipitation_mass_falling_onto_surface_snow (1)
>> 'Solid precipitation refers to the precipitation of water in the solid phase. Water in the atmosphere exists in one of three phases: solid, liquid or vapor. The solid phase can exist as snow, hail, graupel, cloud ice, or as a component of aerosol. The quantity with standard name fraction_of_solid_precipitation_mass_falling_onto_surface_snow is the mass of solid precipitation falling onto snow as a fraction of the mass of solid precipitation falling within the area of interest. The horizontal domain over which the quantity is calculated is described by the associated coordinate variables and coordinate bounds or by a coordinate variable or scalar coordinate variable with the standard name of "region" supplied according to section 6.1.1 of the CF conventions. The phrase "surface_snow" means snow lying on the surface.'
>>
>> Are these okay? If so I think they can be accepted.
>>
>> Best wishes,
>> Alison
>>
>> ------
>> Alison Pamment Tel: +44 1235 778065
>> NCAS/Centre for Environmental Data Archival Email: alison.pamment at stfc.ac.uk
>> STFC Rutherford Appleton Laboratory
>> R25, 2.22
>> Harwell Oxford, Didcot, OX11 0QX, U.K.
>>
>> -----Original Message-----
>> From: CF-metadata <cf-metadata-bounces at cgd.ucar.edu> On Behalf Of Alison Pamment - UKRI STFC
>> Sent: 11 June 2018 11:33
>> To: 'Karl Taylor' <taylor13 at llnl.gov>; Juckes, Martin (STFC,RAL,RALSP) <martin.juckes at stfc.ac.uk>; CF-metadata (cf-metadata at cgd.ucar.edu) <cf-metadata at cgd.ucar.edu>
>> Subject: Re: [CF-metadata] Precipitation fractions for LS3MIP
>>
>> Dear Martin, Karl and Steve,
>>
>> Thank you for the proposing these two names and the comments received so far.
>>
>> fraction_of_rainfall_mass_falling_onto_surface_snow (1) 'The phrase "surface_snow" means snow lying on the surface.'
>>
>> fraction_of_solid_precipitation_mass_falling_onto_surface_snow (1) 'The phrase "surface_snow" means snow lying on the surface. Solid precipitation refers to the precipitation of water in the solid phase. Water in the atmosphere exists in one of three phases: solid, liquid or vapor. The solid phase can exist as snow, hail, graupel, cloud ice, or as a component of aerosol.'
>>
>> The names and units look fine.
>>
>> Are these variables calculated over quite large areas? If so, would it be appropriate to add the following sentence to their definitions:
>> 'The horizontal domain over which the quantity is calculated is described by the associated coordinate variables and coordinate bounds or by a coordinate variable or scalar coordinate variable with the standard name of "region" supplied according to section 6.1.1 of the CF conventions'?
>>
>> This is what we do with names like land_ice_mass where the quantity might represent the mass of a whole ice sheet, rather than something calculated in a small lat-long grid box.
>>
>> Best wishes,
>> Alison
>>
>> ------
>> Alison Pamment Tel: +44 1235 778065
>> NCAS/Centre for Environmental Data Archival Email: alison.pamment at stfc.ac.uk
>> STFC Rutherford Appleton Laboratory
>> R25, 2.22
>> Harwell Oxford, Didcot, OX11 0QX, U.K.
>>
>> From: CF-metadata <cf-metadata-bounces at cgd.ucar.edu> On Behalf Of Karl Taylor
>> Sent: 05 June 2018 17:03
>> To: Steven Emmerson <emmerson at ucar.edu>; Juckes, Martin (STFC,RAL,RALSP) <martin.juckes at stfc.ac.uk>
>> Cc: cf-metadata at cgd.ucar.edu
>> Subject: Re: [CF-metadata] Precipitation fractions for LS3MIP
>>
>> Hi all,
>>
>> I think in common usage "mass fraction" is the ratio of the mass of a particular species to the total mass of all species combined (e.g., the mass fraction of oxygen molecules in air). For the variable considered here, the fraction refers to the ratio of the mass of as particular "species" (e.g., rain) that falls on a particular surface (e.g., surface snow). This is enough different from the standard usage that I think it would be wise to avoid "mass fraction" in the standard name; thus, the suggestion:
>>
>> fraction_of_rainfall_mass_falling_onto_surface_snow
>>
>> Using "mass_fraction" here might lead some to wrongly jump to an interpretation that this had something to do with the fraction of precipitation that was falling as rain.
>>
>> best regards,
>> Karl
>> On 6/5/18 7:55 AM, Steven Emmerson wrote:
>> Greetings,
>>
>> On Tue, Jun 5, 2018 at 3:31 AM, Martin Juckes - UKRI STFC <mailto:martin.juckes at stfc.ac.uk> wrote:
>> We don't want the mass per unit area on snow divided by the mass per unit area on the whole grid cell, but rather, as Jonathan has spelled out, the mass on snow divided by the mass on the whole grid cell. Hence, I support Karl's suggestion of using "mass" in the name, rather than "amount".
>>
>> I believe that's called a "mass fraction". See Table 12 of <https://www.nist.gov/pml/nist-guide-si-chapter-8-comments-some-quantities-and-their-units>.
>>
>> Regards,
>> Steve Emmerson
>>
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Received on Mon Jun 25 2018 - 11:05:34 BST
