[CF-metadata] New standard names for NEMO ocean model output

Jonathan Gregory j.m.gregory at reading.ac.uk
Wed Jan 11 07:17:12 MST 2017


Dear Eric

OK. In that case, I would suggest we rename the existing standard_name
  ocean_mixed_layer_thickness_defined_by_vertical_tracer_diffusivity
which refers to the level at which the diffusivity differs from its surface
value by a certain amount, as
  ocean_mixed_layer_thickness_defined_by_vertical_tracer_diffusivity_deficit
using an alias, and we introduce a new standard name for your definition of
  ocean_mixed_layer_thickness_defined_by_vertical_tracer_diffusivity_threshold
which refers to the level at which the diffusivity falls below a threshold
value (not referred to the surface). Woudl that be OK?

Best wishes

Jonathan

On Wed, Jan 11, 2017 at 11:30:19AM +0000, Eric Boisseson wrote:
> Date: Wed, 11 Jan 2017 11:30:19 +0000
> From: Eric Boisseson <eric.boisseson at ecmwf.int>
> To: j.m.gregory at reading.ac.uk, cf-metadata at cgd.ucar.edu
> CC: Sebastien Villaume <sebastien.villaume at ecmwf.int>, Kevin Marsh
>  <kevin.marsh at ecmwf.int>
> Subject: Re: [CF-metadata] Re: New standard names for NEMO ocean model
>  output
> X-Mailer: Zimbra 8.6.0_GA_1200 (ZimbraWebClient - FF45
>  (Linux)/8.6.0_GA_1200)
> 
> Dear Johnatan,
> 
> Sorry for the delayed answer.
> 
> >> If we could clarify the "defined by" part, would you be content to describe the turbocline as a mixed layer (with appropriate definition)?
> 
> Yes, I'll be fine with that.
> 
> Best regards,
> 
> Eric
> 
> ----- Forwarded Message -----
> From: "Jonathan Gregory" <j.m.gregory at reading.ac.uk>
> To: cf-metadata at cgd.ucar.edu
> Sent: Tuesday, 13 December, 2016 17:46:50
> Subject: [CF-metadata] Fwd: Re: New standard names for NEMO ocean model output
> 
> Dear Eric
> 
> Yes, I see what you mean. If we could clarify the "defined by" part, would you
> be content to describe the turbocline as a mixed layer (with appropriate
> definition)?
> 
> Best wishes
> 
> Jonathan
> 
> > - ocean_turbocline_thickness in m
> > The turbocline thickness is similar to the mixed layer thickness but is estimated in models as the thickness at which the vertical eddy diffusivity coefficient (resulting from the vertical physics alone) falls below a given value defined locally.
> > 
> > You mentioned that this is the same as ocean_mixed_layer_thickness_defined_by_vertical_tracer_diffusivity.
> > 
> > But the definition for this one in the CF table is
> > 
> > "The ocean mixed layer is the upper part of the ocean, regarded as being well-mixed. The base of the mixed layer defined by temperature, sigma, sigma_theta, or vertical diffusivity is the level at which the quantity indicated differs from its surface value by a certain amount. The amount by which the quantity differs can be specified by a scalar coordinate variable."
> > 
> > Unlike with temperature or density criteria, the turbocline thickness is not estimated based on the difference with respect to the vertical diffusivity at the surface. As written in the definition we gave you, when the vertical diffusivity falls below a given value defined locally then we are at the turbocline depth.
> > 
> > #############################
> > 
> > I hope this helps.
> > 
> > Best regards,
> > 
> > Eric
> > 
> > 
> >  
> > 
> > ----- Original Message -----
> > From: "Kevin Marsh" <kevin.marsh at ecmwf.int>
> > To: "Eric Boisseson" <eric.boisseson at ecmwf.int>
> > Sent: Tuesday, 13 December, 2016 14:35:48
> > Subject: Fwd: [CF-metadata]  New standard names for NEMO ocean model output
> > 
> > Hi Eric,
> > some feedback on your feedback...feel free to send any responses directly to the list, or to me if you prefer and i will send the comments to the list.
> > I think that he's happy with 1, so only need input for 2. and 3.,
> > Thanks,
> > Kevin
> > 
> > ----- Forwarded Message -----
> > From: "j m gregory" <j.m.gregory at reading.ac.uk>
> > To: cf-metadata at cgd.ucar.edu
> > Sent: Tuesday, 13 December, 2016 13:56:41
> > Subject: [CF-metadata]  New standard names for NEMO ocean model output
> > 
> > Dear Kevin
> > 
> > > 1. bottom_pressure_equivalent_height (m) 
> > > 3. ocean_steric_height (m)
> > >  
> > > The steric height is estimated as the vertical integral of the density (relative to a reference density where T=0K and S=35psu). The bottom pressure is the mass of the water column at a given location. 
> > 
> > Ah, I see.
> > 
> > For
> > > 3. ocean_steric_height_above_sea_level (m)
> > I would suggest
> > > The ocean steric height above sea level measures the change in thickness of a column of water when its temperature and salinity are changed from standard values of 0°C and 0.035 to the actual values
> > 
> > > The bottom pressure equivalent height is estimated indirectly as the difference between the steric height and the sea level.
> > 
> > I don't follow that, which sounds like the definition of ocean steric height
> > again. However your alternative statement of its being the mass of the column
> > makes sense to me. Going with the latter definition, I would suggest
> > 
> > sea_water_mass_per_unit_area_expressed_as_thickness
> > 
> > and presumably you have to state a standard density to be used in this
> > conversion - what is that? NB sea_water_mass_per_unit_area (kg m-2) is already
> > a standard name.
> > 
> > > 2. Instead of "ocean_turbocline_depth (m)" we suggest:
> > > ocean_turbocline_thickness (m)
> > > 'The turbocline thickness is similar to the mixed layer thickness but is estimated in models as the thickness at which the vertical eddy diffusivity coefficient (resulting from the vertical physics alone) falls below a given value defined locally.'
> > 
> > Is there a difference between that and the existing
> > ocean_mixed_layer_thickness_defined_by_vertical_tracer_diffusivity
> > ?
> > 
> > > ratio_of_sea_water_potential_temperature_anomaly_to_relaxation_timescale (K s-1)
> > > 
> > > 'This term is estimated as the deviation of the local sea water potential temperature from an ocean model wrt an observation-based climatology (eg World Ocean Database) weighted by a user-specified relaxation coefficient in s-1 (1/(relaxation timescale)). The relaxation coefficient depends on the timescale on which the correction is applied.'
> > 
> > It seems to me that the last sentence is probably not necessary, since the
> > previous sentence says the same.
> > 
> > Best wishes and thanks
> > 
> > Jonathan
> > _______________________________________________
> > CF-metadata mailing list
> > CF-metadata at cgd.ucar.edu
> > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
> 
> ----- End forwarded message -----
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