[CF-metadata] Re: standard names for CEOP

From: Jonathan Gregory <j.m.gregory>
Date: Thu, 1 Dec 2005 09:55:24 +0000

Dear Beate

Thanks for your email. I think we have so far agreed

  surface_cover:1 (which extends the idea of land_cover)
  surface_carbon_dioxide_mole_flux:mol s-2 s-1
  tendency_of_water_vapor_content_of_atmosphere_layer_due_to_convection:kg m-2 s-1
  tendency_of_water_vapor_content_of_atmosphere_layer:kg m-2 s-1
  mass_fraction_of_cloud_condensed_water_in_air:1
  surface_downwelling_photosynthetic_photon_flux_in_air:mol m-2 s-1
  surface_net_upward_radiative_flux
  surface_upwelling_photosynthetic_photon_flux_in_air:mol m-2 s-1
  tendency_of_mass_fraction_of_cloud_condensed_water_in_air_due_to_advection: s-1
  convective_cloud_base_height:m
  convective_cloud_top_height:m
  volume_fraction_of_water_in_soil:1

I made a mistake about the units of energy density, which is J m-3=kg m-1 s-2.
Your units of m2 s-2 are specific_energy, not specific_energy_density. Hence
we should have

  specific_kinetic_energy_of_air:m2 s-2

"of" seems more suitable than "in" since it's really a property of the air.

I was also wrong about the definition of dry static energy, which by accident
got confused in the last update. Sorry about that. In some of your original
names, were you proposing "dry energy" to mean enthalpy + kinetic energy? As
far as I can discover this isn't a standard term, is it? - but if we are happy
to introduce new terminology it seems like a good choice to me. If we used
this term, we would have

  specific_dry_energy_of_air:m2 s-2
  dry_energy_content_of_atmosphere_layer:J m-2
  tendency_of_dry_energy_content_of_atmosphere_layer:W m-2
  atmosphere_dry_energy_content:J m-2

the last two being in your original list. I'm sorry but I'm still not clear
which "total" energy you mean for the east/north/upward energy flux and the
atmosphere energy content. Is it just this dry energy or does it include
latent heat as well? For instance, Peixoto and Oort equation 13.1e calls
enthalpy (= internal + potential) + kinetic + latent the "total" energy. By
analogy with dry_energy we could call this sum the moist_energy, which I'd
prefer as I think "total" is uninformative.

In your first posting, you had names of atmosphere_east/northward_water_vapour
_flux_content and I suggested these might be east/northward_water_vapor_flux.
In your subsequent email you say they have units of kg m-1 s-1. In that case,
now understanding your original proposal, I suppose these are the vertically
integrated transport across unit distance normal to the transport - is that
right? If so their names should be

  eastward_atmosphere_water_vapor_transport_across_unit_distance:kg m-1 s-1
  northward_atmosphere_water_vapor_transport_across_unit_distance:kg m-1 s-1

corresponding to existing dry_static_energy_transport names.

The choice between X_at_convective_cloud_base and convective_cloud_base_X is
difficult. We *could* simplify it but I initially chose what seemed more
natural to me in English, which was the former if X is somehow "measured" at
that level and the latter if X is a property of that level. Hence your new
proposal

  air_temperature_at_cloud_top

is fine for me!

There are still some outstanding questions from last time:

* Is this both land ice and sea ice?

- ice_area_fraction; 1

* I'm not sure what this means:

- tendency_of_atmosphere_mass_content; kg m-2 s-1

Does it refer to the total mass of the atmosphere?

* What mass is moving in these quantities?

- eastward_mass_flux_in_air; kg m-1 s-1
- northward_mass_flux_in_air; kg m-1 s-1
- upward_mass_flux_in_air; kg m-1 s-1

* I'm unclear what this means

- surface_moisture; kg m-2

* You have proposed

- volume_fraction_of_water_in_soil_layer; 1

I don't think that's necessary. The volume fraction is an intensive quantity,
not the property of a layer. The layer number might be specified as a vertical
coordinate, of course.

* In your new proposals
 
- surface_direct_downwelling_photosynthetic_radiative_flux; W m-2
- surface_diffuse_downwelling_photosynthetic_radiative_flux; W m-2

is it correct that you mean the vertically downward component of the flux
directly from the sun in the first case, while the second means
surface_downwelling_photosynthetic_radiative_flux minus
surface_direct_downwelling_photosynthetic_radiative_flux?

Cheers

Jonathan
Received on Thu Dec 01 2005 - 02:55:24 GMT