[CF-metadata] Proposed CF standard names for the NEMO ocean model

From: Jonathan Gregory <j.m.gregory>
Date: Fri, 8 Aug 2008 18:31:45 +0100

Dear Ian

We now agree on

Rename:
 
water_flux_into_ocean
water_flux_into_ocean_from_rivers
water_volume_transport_into_ocean_from_rivers
wind_mixing_energy_flux_into_ocean
water_flux_into_ocean_without_flux_correction (proposal agreed with Martina)

by replacing "ocean" with "sea_water".

Include Newtonian relaxation in the definitions of water_flux_into_sea_water,
water_flux_out_of_sea_water (T5), water_flux_out_of_sea_ice_and_sea_water
(T3), virtual_salt_flux_into_sea_water (T6).
 
New names:

T1 water_flux_out_of_sea_water_due_to_sea_ice_thermodynamics (kg m-2 s-1)
T3 water_flux_out_of_sea_ice_and_sea_water (kg m-2 s-1)
T4 minus_one_times_water_flux_into_sea_water_from_rivers (kg m-2 s-1)
T5 water_flux_out_of_sea_water (kg m-2 s-1)
T6 virtual_salt_flux_into_sea_water (kg m-2 s-1)
T7 ocean_mixed_layer_thickness_defined_by_vertical_tracer_diffusivity (m)
T8 heat_flux_into_sea_water_due_to_newtonian_relaxation (W m-2)
T9 water_flux_out_of_sea_water_due_to_newtonian_relaxation (kg m-2 s-1)
T10 virtual_salt_flux_into_sea_water_due_to_newtonian_relaxation (kg m-2 s-1)
T11 ocean_rigid_lid_pressure_expressed_as_sea_surface_height_above_geoid (m)
T12 model_level_number_at_base_of_ocean_mixed_layer_defined_by_sigma_theta (1)
T13 depth_at_maximum_upward_derivative_of_sea_water_potential_temperature (m)
T15 integral_of_sea_water_potential_temperature_wrt_depth_expressed_as_heat_content (J m-2)
T17 sea_ice_albedo (1)
U2 bolus_sea_water_x_velocity (m s-1)
U3 x_derivative_of_ocean_rigid_lid_pressure (N m-3)
V2 bolus_sea_water_y_velocity (m s-1)
V3 y_derivative_of_ocean_rigid_lid_pressure (N m-3)
G4 angle_of_rotation_from_east_to_x (degree)
G5 angle_of_rotation_from_east_to_y (degree)
G6 cell_area (m2)
G7 model_level_number_at_sea_floor (1)

Diffusivities:

You pointed out Martina's proposed ocean_vertical_tracer_diffusivity and we
also have atmosphere_heat_diffusivity and atmosphere_momentum_diffusivity.
Hence I think we should have ocean, not sea_water, for consistency. Would you
be happy with

W2 ocean_vertical_heat_diffusivity (m2 s-1)
W3 ocean_vertical_tracer_diffusivity_due_to_convection (kg m-2 s-1)
W4 ocean_vertical_momentum_diffusivity (m2 s-1)
W5 ocean_vertical_momentum_diffusivity_due_to_convection (m2 s-1)
W6 ocean_vertical_salt_diffusivity (m2 s-1)
W7 vertical_component_of_ocean_xy_tracer_diffusivity (m2 s-1)

The distinction atmos/air and ocean/sea_water is a bit tricky. It started with
the best of intentions, because it is "natural" to use atmos/ocean for
large-scale ideas, such as atmos water transport and ocean heat content, and
"natural" to use air/sea_water for small-scale ones like air temperature and
sea-water density. But in the middle there are things like diffusivity where
it is unclear whether they are properties of the substance or the medium.

There's another issue we have not considered in your names or Martina's, that
stress is a tensor, so we might have to become clear about whether "vertical
momentum diffusivity" means the diffusivity is vertical or the momentum is
vertical. At present we do not consider vertical momentum since our models are
hydrostatic. We can cross that bridge when we come to it, if you like; at that
time we could alias the existing names to more precise replacements. (NB In
W7 I have repositioned the "xy".)

If T2 applies to the open ocean, it needs "where ice_free_sea" in its
cell_methods, as well as its standard name. Without that, it applies to the
whole grid box, both sea-ice and leads.

T14. I don't think we can have a standard name just to suit stashcodes!
Geopotential height with different vertical coordinates will also get mapped
to a common stash code. We have to make the translators use a combination of
metadata to translate the stash code, not the standard name alone. So I think
we should stick with plain depth for this.

G1-3. I like your suggestion of "position", to be defined in these standard
names as a vector in units of distance. Would it be OK to state in the
guidelines that "derivative" is to be understood as "partial derivative"? Then
we can have

G1 magnitude_of_derivative_of_position_wrt_x_coordinate_index (m)
G2 magnitude_of_derivative_of_position_wrt_y_coordinate_index (m)
G3 magnitude_of_derivative_of_position_wrt_model_level_number (m)

Best wishes

Jonathan
Received on Fri Aug 08 2008 - 11:31:45 BST