Dear Jonathan,
"Condensed_water" is indeed the phrase used in CF standard names to refer to liquid water and ice collectively, not just liquid. Essentially it means "non gaseous H2O". We also have names that refer separately to "liquid_water" and "ice" so that all the quantities can be distinguished. For water in all its phases (collectively) we simply use the term "water". I can't presently think of a concise alternative to "condensed_water" to describe the necessary concept. I suppose we could be more explicit and use "liquid_water_and_ice" although this would make the names longer. Do others have strong feelings about this?
"Condensed_water" is used in 22 existing names, 16 of which refer to cloud. The other 6 are soil water quantities.
I think the existing name effective_radius_of_cloud_condensed_water_particles_at_cloud_top is certainly the quantity you are looking for. However, I take your point about particles and I agree that it would actually make more sense to change this name to effective_radius_of_cloud_particles_at_cloud_top. It is shorter (always a plus point!) and it is consistent with the general approach that we have taken before that, unless we explicitly distinguish between different types of object, (e.g. convective/stratiform cloud, seasalt/sulfate aerosol, latent/sensible heat flux, etc.) then the name applies to the generic object (cloud, aerosol, heat flux).
I don't think we need to change any of the other condensed_water names, even the cloud ones, because they don't refer to particles. For example, mass_fraction_of_cloud_condensed_water_in_air and mass_concentration_of_condensed_water_in_soil still seem OK.
Best wishes,
Alison
------
Alison Pamment Tel: +44 1235 778065
NCAS/British Atmospheric Data Centre Email: alison.pamment at stfc.ac.uk
STFC Rutherford Appleton Laboratory
R25, 2.22
Harwell Oxford, Didcot, OX11 0QX, U.K.
> -----Original Message-----
> From: Jonathan Wrotny [mailto:jwrotny at aer.com]
> Sent: 18 December 2013 19:17
> To: Pamment, Alison (STFC,RAL,RALSP); cf-metadata at cgd.ucar.edu
> Subject: Re: [CF-metadata] Proposed new standard name:
> effective_radius_of_cloud_particle_at_cloud_top
>
> Dear Alison,
>
> Thanks for the information. I had been looking at an older version of
> the standard names table by accident and missed this quantity. However,
> after looking at it, I am a little confused by the phrase
> "condensed_water." I think of condensed water as liquid water that has
> condensed from water vapor, but definition states: "condensed_water"
> means liquid and ice. Why is ice included here? Is "condensed" to be
> interpreted more generally such that liquid and/or ice particles are
> included in the cloud? If the latter, then why not use a more general
> phrase such as "cloud_particle" to cover all types of possible
> particles: e.g. liquid, ice, mixed liquid/ice? To me, the use of
> "condensed_water" in the name then "liquid and ice" in the definition is
> confusing.
>
> If this standard name is meant apply to both liquid and/or ice particles
> in the cloud, then I think that it could suffice for our GOES-R data
> product, but in that case, I would suggest a minor re-write of the name.
>
> Sincerely,
>
> Jonathan
>
> On 12/17/2013 6:58 AM, alison.pamment at stfc.ac.uk wrote:
> > Dear Jonathan and Randy,
> >
> > You are correct that we already have the standard name
> effective_radius_of_cloud_liquid_water_particle_at_liquid_water_cloud_to
> p which is obviously aimed at liquid particles. We do, however, also have
> the existing name
> effective_radius_of_cloud_condensed_water_particles_at_cloud_top
> defined as: 'The effective radius of a size distribution of particles, such as
> aerosols, cloud droplets or ice crystals, is the area weighted mean radius of
> particle size. It is calculated as the ratio of the third to the second moment
> of the particle size distribution. "cloud_top" refers to the top of the highest
> cloud. "condensed_water" means liquid and ice.' I think this is probably the
> quantity you need, rather than adding another standard name.
> >
> > Best wishes,
> > Alison
> >
> > ------
> > Alison Pamment Tel: +44 1235 778065
> > NCAS/British Atmospheric Data Centre Email:
> alison.pamment at stfc.ac.uk
> > STFC Rutherford Appleton Laboratory
> > R25, 2.22
> > Harwell Oxford, Didcot, OX11 0QX, U.K.
> >
> >
> > From: CF-metadata [mailto:cf-metadata-bounces at cgd.ucar.edu] On
> Behalf Of Jonathan Wrotny
> > Sent: 15 December 2013 21:56
> > To: cf-metadata at cgd.ucar.edu
> > Subject: [CF-metadata] Proposed new standard name:
> effective_radius_of_cloud_particle_at_cloud_top
> >
> > Dear CF board,
> >
> > Back in May, a colleague of mine, Randy Horne, submitted a new proposed
> name for the effective radius of a cloud particle at the top of a cloud. Our
> proposed standard name was
> "effective_radius_of_cloud_particle_at_cloud_top". We did not hear back
> from any CF posters at the time in regards to this proposal, and are hoping
> to re-start this proposal now.
> >
> > The motivation for this new standard name is a data product on the future
> GOES-R geostationary platform. This product is the effective radius for a
> cloud particle at the top of a cloud. The GOES-R product will not distinguish
> between water and ice particles, however. Currently, the CF database has a
> similar standard name but for liquid particles only
> (effective_radius_of_cloud_liquid_water_particle_at_liquid_water_cloud_t
> op). This standard name does not suffice for the GOES-R data product,
> hence, the proposal for a slightly more general standard name which would
> cover both water and ice particles at the cloud top. Here is our current
> proposal:
> >
> > Standard Name:
> >
> > effective_radius_of_cloud_particle_at_cloud_top
> >
> > Definition:
> >
> > The effective radius of a size distribution of particles, such as aerosols,
> cloud droplets or ice crystals, is the area weighted mean radius of particle
> size. It is calculated as the ratio of the third to the second moment of the
> particle size distribution. cloud_top refers to the top of the highest cloud
> and cloud_particle refers to either a liquid water droplet or ice crystal.
> >
> > Canonical Units:
> >
> > m
> >
> > Thanks for your consideration of this proposal. All comments are
> welcome.
> >
> > Sincerely,
> >
> > Jonathan Wrotny
--
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Received on Thu Dec 19 2013 - 04:44:15 GMT
