Dear Jonathan,
Thanks again.
On Fri, 2008-08-08 at 18:31 +0100, Jonathan Gregory wrote:
> 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)
>
Agreed.
> 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)
>
They sound good to me.
> 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.
>
Thanks - I assumed that was the ocean/sea_water distinction, but as you
say, (eddy) diffusivity is neither one thing nor the other.
> 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.
I agree. I'd favour something explicit like
"zz_component_of_tracer_isopycnal_diffusivity". But let's not worry
about it now.
> (NB In
> W7 I have repositioned the "xy".)
>
That's fine.
> 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.
>
I see. T2 is defined everywhere, so we won't need to restrict its
domain with cell_methods.
> 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.
>
I think that sounds the right thing to do in the long term, but in the
short term why can't we have ocean_isotherm_depth (m) for people to
choose if they wish? I think it's a bit of a "special case" for
oceanographers, don't you? (I'm not sure how many of them would look at
"depth" in a list of variables in a file and say to themselves "I'll
just go and check the coordinates to see it this is the isotherm depth"?
To me, a 2D field of "depth" would suggest sea-floor depth. And I'd
probably ignore it.) And even if you don't like this, I think it would
still help in the short term to have ocean_isotherm_depth - we can
always revert to "depth" once the metadata machinery is in place to
handle it.
> 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"?
Yes, I think that's a good idea - something along the lines of
"derivative_of_X_wrt_Y | [X]/[Y] | dX/dY (keeping any other independent
variables constant, ie the partial derivative if appropriate).
> 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)
>
That sounds good.
So, apart from T14, I think we're agreed. If you can let me know your
thoughts on that, I'll set up a final list, with units and definitions,
and post it here.
Regards and best wishes,
Ian.
> Best wishes
>
> Jonathan
--
Ian Culverwell B-2-81 Ocean and Sea Ice Modelling
Met Office FitzRoy Road Exeter Devon EX1 3PB United Kingdom
Tel: +44 (0)1392 884017 Fax: +44 (0)1392 885861
E-mail: ian.culverwell at metoffice.gov.uk http://www.metoffice.gov.uk
Met Office climate change predictions can now be viewed on Google Earth
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Received on Mon Aug 11 2008 - 01:58:44 BST
