Hi Jonathan, I asked around among the (abominable?) snow people I know, and
they don't seem overly concerned about the standard name, whether it
continues to say snowfall_flux (recall that the CMIP short name or cryptic
name for this quantity is "prsn", which won't change...) or something more
correct like frozen or solid water. But the one important thing is that
this quantity + rainfall flux should add up to total precipitated water
flux. If it didn't, a lot of subsequent calculations would go awry.

I don't have a strong opinion on frozen vs solid, or on the soil variables,
beyond a general reluctance to change anything that is already in the
standard, or to add aliases unless necessary.

Thanks,

V. Balaji                            Office:     +1-609-452-6516
Head, Modeling Systems Group, GFDL   Mobile:     +1-917-273-9824
Princeton University                 Email:
balaji@princeton.eduhttps://www.gfdl.noaa.gov/v-balaji-homepage


On Fri, Apr 6, 2018 at 5:38 PM, Jonathan Gregory <j.m.greg...@reading.ac.uk>
wrote:

> 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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> > > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
> >
> > ----- End forwarded message -----
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>
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