Dear Jonathan,
Thanks for your comments.
> Thanks very much. Having the definitions detail the processes helps a lot.
> I do have a remaining concern about terminology, though, which probably should
> have been noticed earlier. In the guidelines, "condensed water" means liquid
> or solid (ice), for instance in mass_fraction_of_cloud_condensed_water_in_air,
> which says this explicitly in its definition.
> For consistency, "condensation" should mean gas -> liquid or solid. The
> A Met Soc glossary says "in general" that's what condensation means, but
> in meteorology it means gas -> liquid.
> http://glossary.ametsoc.org/wiki/Condensation
> It's unfortunate that it's ambiguous! I think the general definition is
> more satisfactory.
> The same entry says "evaporation" means liquid or solid -> gas i.e. the reverse
> of condensation. That is the sense in which we use it in some other standard
> names e.g. water_evaporation_flux. However the AMS entry for evaporation gives
> this as its first sense, but remarks that it's "usually" liquid->gas. Again, an
> unsatisfactory ambiguity, and I would prefer the broader definition. With the
> broader definitions, deposition (gas -> solid) is a subset of condensation,
> and sublimation (solid -> gas) a subset of evaporation.
>
> It looks like we may have some existing inconsistency between the meanings of
> condensation and perhaps evaporation in standard names. Do you agree? If so we
> should try to sort it out. An advantage of the broader definitions is you would
> not have to say condensation_and_deposition, since it's all condensation.
I've given this quite a bit of thought and I'm afraid that I'm unsure
about the best way to proceed. Personally I prefer the definition
in common usage in meterology which restricts condensation and
evaporation to vapour/liquid transitions and uses deposition/
sublimation as well. I see this as more precise because it allows
for the future possibility of supporting variables which separate
condensation and deposition for example. But I also very much take
your point that this is potentially inconsistent with other terms
already defined in the standard names such as water_evaporation_flux
/condensed_water. (I think that the current standard names are
consistent in this sense - but I may have missed something. Was
there a particular inconsistency that you had spotted?)
For the moment I have modified my proposal to remove references
to condensation/evaporation - hopefully the definitions below
are now unambigous. This has required removing a couple of
variables. I will think about the best way to propose these
at a future date. I'll have to decide whether to adopt
your suggestion or whether to propose more wide ranging changes
to the standard names to make them consistent with my preferred
definition for condensation/evaporation.
Here is my updated proposal. Please let me know if you have any
concerns with it is it now stands.
Thanks!
Mark
Name:tendency_of_air_temperature_due_to_stratiform_cloud_and_precipitation
Decription:The specification of a physical process by the phrase due_to_process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "tendency_of_X" means derivative of X with respect to time. Air temperature is the bulk temperature of the air, not the surface (skin) temperature. This variable should contain net latent heating effects of all processes which convert stratiform clouds and precipitation between water vapour, liquid or ice phases.
Units: K s-1
Name:tendency_of_specific_humidity_due_to_stratiform_cloud_and_precipitation
Description:The specification of a physical process by the phrase due_to_process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "tendency_of_X" means derivative of X with respect to time. "specific" means per unit mass. Specific humidity is the mass fraction of water vapor in (moist) air. This variable should contain the effects of all processes which convert stratiform clouds and precipitation to or from water vapor.
Units: s-1
Name:effective_radius_of_stratiform_cloud_liquid_water_particle_at_stratiform_liquid_water_cloud_top
Description: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. stratiform_liquid_water_cloud_top refers to the top of the highest stratiform liquid water cloud.
Units:m
Name:effective_radius_of_convective_cloud_liquid_water_particle_at_convective_liquid_water_cloud_top
Description: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. convective_liquid_water_cloud_top refers to the top of the highest convective liquid water cloud.
Units:m
Name:number_concentration_of_stratiform_cloud_liquid_water_particle_at_stratiform_liquid_water_cloud_top
Description:"Number concentration" means the number of particles or other specified objects per unit volume. stratiform_liquid_water_cloud_top refers to the top of the highest stratiform liquid water cloud.
Units:m
Name:number_concentration_of_convective_cloud_liquid_water_particle_at_convective_liquid_water_cloud_top
Description:"Number concentration" means the number of particles or other specified objects per unit volume. convective_liquid_water_cloud_top refers to the top of the highest convective liquid water cloud.
Units:m
Name:atmosphere_mass_content_of_convective_cloud_condensed_water
Description:"condensed_water" means liquid and ice. "Content" indicates a quantity per unit area. The "atmosphere content" of a quantity refers to the vertical integral from the surface to the top of the atmosphere. For the content between specified levels in the atmosphere, standard names including content_of_atmosphere_layer are used.
Units: kg m-2
Name:atmosphere_mass_content_of_convective_cloud_ice
Description:"Content" indicates a quantity per unit area. The "atmosphere content" of a quantity refers to the vertical integral from the surface to the top of the atmosphere. For the content between specified levels in the atmosphere, standard names including content_of_atmosphere_layer are used.
Units: kg m-2
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Mark Webb Climate Scientist
Met Office Hadley Centre
FitzRoy Road Exeter EX1 3PB United Kingdom
Tel: +44 (0)1392 884515 Fax: +44 (0)1392 885681
E-mail:mark.webb at metoffice.gov.uk http://www.metoffice.gov.uk
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Received on Wed Jul 15 2015 - 11:36:55 BST
