[CF-metadata] New Cryospheric variables

From: Jonathan Gregory <j.m.gregory>
Date: Wed, 11 Feb 2009 20:20:36 +0000

Dear Siobhan

I've commented on most of your names, below. A general comment: standard names
are case-sensitive and entirely in lower case.

> Sea_ice_albedo
is already in the table

> Sea_ice_thickness_in_sea_ice_categories
> Sea_ice_area_fraction_in_sea_ice_categories
The category is a kind of coordinate variable, so the standard names for
these should be sea_ice_thickness and sea_ice_area_fraction, with some
appropriate coordinate variable. Is it just an index or is it a physical
quantity?

> Surface_temperature_in_sea_ice
Would surface_temperature be sufficient?

> Temperature_at_sea_ice_snow_interface
Could this be
  temperature_at_sea_ice_surface
If not, I'd suggest temperature_at_interface_of_sea_ice_and_snow for clarity.

> Sea_ice_age
Could you define this?

> Sea_ice_growth_due_to_*
We have a standad name
  tendency_of_sea_ice_thickness_due_to_thermodynamics
which is in m s-1. Your quantities are in kg m-2. I would suggest that a
rate might be a more robust quantity i.e. kg m-2 s-1 because time-bounds
are sometimes not supplied and without them a change is hard to interpret.
We haven't got a name for sea-ice in kg m-2 at present. I'd suggest either
  sea_ice_amount
like snow_amount, or
  sea_ice_mass_per_unit_area
like the corresponding atmosphere name. Which do you (and others) think is
better? Then we could have
  tendency_of_sea_ice_amount_due_to_thermodynamics
in general - you haven't asked for this - and specifically
  tendency_of_sea_ice_amount_due_to_*
where processes arre congelation, lateral_accretion and snow_ice_formation.
Frazil is not a process - would the process be frazil_accretion? If you're
sure that the change is better, not s-1, substitute change_in for
tendency_of - we have a couple of change_in names in the table.

> Sea_ice_melt_amount_at_ice_surface
> Sea_ice_melt_amount_at_ice_base
> Sea_ice_melt_amount_at_lateral_sides
sea_ice_melt_amount in kg m-2 is like surface_snow_melt_amount, so that's
consistent. We have _at_sea_ice_base in the table already, so I'd suggest
  sea_ice_melt_amount_at_sea_ice_surface
  sea_ice_melt_amount_at_sea_ice_base
  sea_ice_melt_amount_at_sides
since sides are always lateral!

> Sea_ice_total_heat_content
This is probably analogous to
  integral_of_sea_water_potential_temperature_wrt_depth_expressed_as_heat_content
which is in J m-2. The sea-ice quantity would be
  integral_of_sea_ice_temperature_wrt_depth_expressed_as_heat_content
But you have J. Do you mean you integrate also over the entire area of
sea-ice? If so, omit _content for a quantity in J; we use "content" to mean
"per unit area" in many names. The reason for the long name is to emphasise
that the zero of heat content is arbitrary. It's really a temperature
integral multiplied by a conversion factor.

> Downward|Upward_shortwave|longwave_flux_at_sea_ice_surface
How do these differ from
  surface_downwelling|upwelling_shortwave|longwave_flux
which are already in the table? If you want to specify a mean over the
sea-ice area only, this can be done by cell_methods. Similarly, I am not
sure there's a need for sensible and latent heat fluxes. We already have
  surface_upward|downward_sensible|latent_heat_flux

> Downward_sea_ice_freshwater_flux.
Could you explain what this is?

> Sea_ice_volume_transport_at_Fram_strait
In your doc this is sea_ice_transport_at_fram_strait in kg s-1. For this I
would propose sea_ice_transport_across_line, which is already in the table,
with fram_strait to be named by a coordinate variable of region.

For surface stresses, we already have
  surface_downward_eastward|northward_stress
and
  downward_eastward|northward_stress_at_sea_ice_base
Do these meet the need?

> Eastward_internal_stress_at_sea_ice_base,
> Northward_internal_stress_in_sea_ice
Why are these at_sea_ice_base? By analogy with
  atmosphere_eastward|northward_stress_due_to_gravity_wave_drag
for these "body forces" I would propose
  sea_ice_northward|eastward_stress_due_to_*
where it might be due_to rheology, coriolis_acceleration, sea_surface_tilt.

> Sea_ice_strain_rate_due_to_*
Is strain rate a tensor?

> Sea_ice_ridging_rate
Could you define this?

> Snow_density
is already in the table

> Snow_age
Could you define this?

> Snow_thermal_energy_content
As above,
  integral_of_snow_temperature_wrt_depth_expressed_as_heat_content
In this case, you have specified J m-2 i.e. content.

? Liquid_water_content_in_snow_layer
is already in the table as
  liquid_water_content_of_snow_layer

> Liquid_water_content_in_permafrost_layer
> Liquid_water_content_in_active_layer
by analogy _of_ rather than _in_

I'm aware that "active layer" is the term in use by experts in that area,
but I would suggest that for the more general audience of CF standard names
we need a more informative term. What about seasonally_frozen_soil_layer?

> Temperature_profile_in_*
I would say this quantity is
  soil_temperature
where the "profile" is specified by its depth coordinate.

> Land_ice_geothermal_heat_flux
This is not specific to land_ice. Could we just have geothermal_heat_flux?

> Surface_ice_melt_amount
Suggest land_ice_melt_amount.

> Superimposed_ice_formation_in_ice_sheet
Could we consider
  tendency_of_land_ice_thickness_due_to_superimposed_ice_formation
or
  tendency_of_land_ice_thickness_due_to_refreezing_of_melt_water
which might be more self-explanatory? Or change_in if not tendency_of.

> Runoff_flux_due_to_ice_sheet_melt
To be precise and consistency with other names
  surface_runoff_flux_due_to_land_ice_melt

> Land_ice_melt_rate_at_ice_shelf_base
If it's an ice-shelf, I'm not sure it's land ice! But anyway ice_shelf is
sufficient. Could it be
  ice_shelf_lwe_basal_melt_rate
by analogy with the existing
  land_ice_lwe_basal_melt_rate

> Marine_ice_accretion_rate_at_ice_shelf_base
By analogy, I would propose
  tendency_of_ice_shelf_thickness_due_to_accretion_at_ice_shelf_base

> Ocean_temperature_in_ice_shelf_cavity
> Ocean_salinity_in_ice_shelf_cavity
> Ocean_temperature_at_ice_shelf_cavity_front
> Ocean_salinity_at_ice_shelf_cavity_front
The basic CF names are sea_water_temperature and sea_water_salinity. It seems
to me that the cavity is a kind of geographical location - I'm not sure if
it's necessary to include it in the standard name. On the other hand, you
could say it was like a named surface or layer. Hmm - tricky.

> Surface_orography_at_ice_sheet_surface.
The standard name is surface_altitude. Again, cell_methods could be used if
you specifically wanted a mean over land-ice area only.

Best wishes

Jonathan
Received on Wed Feb 11 2009 - 13:20:36 GMT