Dear Martin

I agree with you that frozen_precipitation_flux seems a bit more surprising in
some way than solid_precipitation_flux. If we put "solid" instead of "frozen",
should we change (by alias) the existing names that have "frozen", which are

frozen_water_content_of_soil_layer
lwe_thickness_of_frozen_water_content_of_soil_layer
mass_fraction_of_frozen_water_in_soil_moisture
mass_fraction_of_unfrozen_water_in_soil_moisture
soil_frozen_water_content
surface_frozen_carbon_dioxide_amount
volume_fraction_of_frozen_water_in_soil

I'm sure there must be others with useful comments to make about this.

Best wishes

Jonathan


----- Forwarded message from Martin Juckes - UKRI STFC 
<martin.juc...@stfc.ac.uk> -----

> Date: Fri, 6 Apr 2018 15:06:15 +0000
> From: Martin Juckes - UKRI STFC <martin.juc...@stfc.ac.uk>
> To: Jonathan Gregory <j.m.greg...@reading.ac.uk>
> Subject: Re: [CF-metadata] CMIP6 data request: Precipitation of solid phase
>       water
> 
> Dear Jonathan,
> 
> 
> It may be that the situation of interest in soil is a change brought about by 
> decreasing temperature, and that the nature of the resulting substance is 
> somewhat complex because of the matrix of soil that is carrying it. In the 
> atmosphere I feel that applying the term "frozen" is a bit of a stretch, 
> though I agree that it would be possible to state that as our intended 
> meaning within the CF convention. On the other hand, we already use "liquid" 
> (as in cloud_liquid_water) and "vapor" for the other two phases, so there is 
> an argument for sticking to the standard partition solid/liquid/vapor.
> 
> 
> Taking your other comments into account, the term would be either 
> "frozen_precipitation_flux" or "solid_precipitation_flux". 
> "frozen_precipitation" looks misleading to me, but perhaps that is a matter 
> of taste.
> 
> 
> As you say, it would be good to hear other opinions (I'll be on leave for the 
> next few days, and will pick up the discussion at the end of next week),
> 
> 
> regards,
> 
> Martin
> 
> 
> 
> ________________________________
> From: CF-metadata <cf-metadata-boun...@cgd.ucar.edu> on behalf of Jonathan 
> Gregory <j.m.greg...@reading.ac.uk>
> Sent: 06 April 2018 14:38
> To: cf-metadata@cgd.ucar.edu
> Subject: Re: [CF-metadata] CMIP6 data request: Precipitation of solid phase 
> water
> 
> Dear Martin
> 
> That's a good point about snow and ice. I think we should use modified help-
> text to make clear that "frozen water" means any form of solid water. I can't
> recall the reason for "frozen" rather than "solid" - I guess because it felt
> more obvious, if less systematic. I think I'm happy to understand "frozen
> water" as "water in the solid phase", however it got into that state. I wonder
> if others feel differently.
> 
> Best wishes
> 
> Jonathan
> 
> ----- Forwarded message from Martin Juckes - UKRI STFC 
> <martin.juc...@stfc.ac.uk> -----
> 
> > Date: Thu, 5 Apr 2018 17:29:08 +0000
> > From: Martin Juckes - UKRI STFC <martin.juc...@stfc.ac.uk>
> > To: "cf-metadata@cgd.ucar.edu" <cf-metadata@cgd.ucar.edu>,
> >        "j.m.greg...@reading.ac.uk" <j.m.greg...@reading.ac.uk>
> > Subject: Re: [CF-metadata] CMIP6 data request: Precipitation of solid phase
> >        water
> >
> > Dear Jonathan,
> >
> >
> > I hadn't spotted the existing usage of frozen_water. My only reservation is 
> > that for such names the help text says '"frozen_water" means ice', which 
> > would exclude snow. The existing usages of "frozen_water" are all soil 
> > quantities for which the subtlety of the distinction between ice and snow 
> > is irrelevant. We could modify the help text for atmospheric variables, but 
> > is the term "frozen" appropriate for all solid phase water in the 
> > atmosphere?  Freezing is a process of transforming to solid phase through a 
> > reduction in temperature, which might be considered inappropriate for some 
> > atmospheric ice and snow formation pathways ... I'm not sure about this, 
> > what do you think?
> >
> >
> > regards,
> >
> > Martin
> >
> >
> > ________________________________
> > From: CF-metadata <cf-metadata-boun...@cgd.ucar.edu> on behalf of Jonathan 
> > Gregory <j.m.greg...@reading.ac.uk>
> > Sent: 05 April 2018 18:18
> > To: cf-metadata@cgd.ucar.edu
> > Subject: [CF-metadata] CMIP6 data request: Precipitation of solid phase 
> > water
> >
> > Dear Martin
> >
> > I agree with the need, but I note that the guidelines propose the phrase
> > frozen_water for solid water, and this is already used in several standard
> > names.
> >
> > Although "precipitation" is used in the world at large for species other 
> > than
> > water, so far in CF standard names it's used only for water. Hence we can 
> > omit
> > "water" for consistency.
> >
> > In view of these two points, would frozen_precipitation_flux be OK?
> >
> > Best wishes
> >
> > Jonathan
> >
> > ----- Forwarded message from Martin Juckes - UKRI STFC 
> > <martin.juc...@stfc.ac.uk> -----
> >
> > > Date: Tue, 3 Apr 2018 11:46:50 +0000
> > > From: Martin Juckes - UKRI STFC <martin.juc...@stfc.ac.uk>
> > > To: "cf-metadata@cgd.ucar.edu" <cf-metadata@cgd.ucar.edu>
> > > Subject: [CF-metadata] CMIP6 data request: Precipitation of solid phase 
> > > water
> > >
> > > Dear All,
> > >
> > >
> > > The CMIP6 data request includes a request for a variable representing the 
> > > precipitation flux of water in a solid phase (including snow and ice). 
> > > This variable was also in CMIP5. The current CMIP6 data request follows 
> > > CMIP5 usage in adopting the standard name "snowfall_flux" for this 
> > > variable, which is not really correct. There may have been a time when 
> > > all solid precipitation in CMIP models was snow, but I think we need a 
> > > more precise name now.
> > >
> > >
> > > We have "rainfall_flux" for precipitation of liquid phase water, but in 
> > > other terms the construction "liquid_water" is used to refer to the 
> > > liquid phase, e.g. "mass_concentration_of_liquid_water_in_air", so 
> > > "solid_water" is a natural extension.
> > >
> > >
> > > I propose a new standard name for solid phase precipitation:
> > >
> > >
> > > precipitation_flux_of_solid_water [kg m-2 s-1]
> > >
> > > In accordance with common usage in geophysical disciplines, "flux" 
> > > implies per unit area, called "flux density" in physics. "solid_water" 
> > > refers to all forms of the solid phase of water.
> > >
> > >
> > > regards,
> > >
> > > Martin
> > > _______________________________________________
> > > CF-metadata mailing list
> > > CF-metadata@cgd.ucar.edu
> > > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
> >
> > ----- End forwarded message -----
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> > CF-metadata@cgd.ucar.edu
> > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
> 
> ----- End forwarded message -----
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