Dear Sebastien and Roy

Thanks. I agree that it's a good idea to include sea_water_.

Best wishes

Jonathan

On Thu, Apr 05, 2018 at 07:04:26PM +0000, Sebastien Villaume wrote:
> Date: Thu, 5 Apr 2018 19:04:26 +0000 (GMT-00:00)
> From: Sebastien Villaume <sebastien.villa...@ecmwf.int>
> To: cf-metadata@cgd.ucar.edu
> Cc: Jonathan Gregory <j.m.greg...@reading.ac.uk>, "Lowry, Roy K."
>  <r...@bodc.ac.uk>
> Subject: Re: [CF-metadata] how to     use
>  ocean_mixed_layer_thickness_defined_by_*
> X-Mailer: Zimbra 8.6.0_GA_1200 (ZimbraWebClient - FF59
>  (Linux)/8.6.0_GA_1200)
> 
> Dear Jonathan and Roy,
> 
> thank you for your suggestions.
> 
> I am happy to go with a set of general standard names if it is fine with 
> everyone. I find it actually useful to make the standard names reusable by 
> not hard-coding one of the reference. It is pretty clear from the mixed layer 
> definition that it is a difference with respect to the sea surface.
> 
> I am also happy to prefix sigma_theta and sigma_t with sea_water:
> 
> sea_water_temperature_difference (K)
> sea_water_sigma_theta_difference (kg/m3)
> sea_water_sigma_t_difference (kg/m3)
> 
> I will draft some definitions for tomorrow. 
> 
> thanks!
> 
> /Sébastien
> 
> ----- Original Message -----
> > From: "Lowry, Roy K." <r...@bodc.ac.uk>
> > To: cf-metadata@cgd.ucar.edu, "Jonathan Gregory" <j.m.greg...@reading.ac.uk>
> > Sent: Thursday, 5 April, 2018 18:34:48
> > Subject: Re: [CF-metadata] how to   use     
> > ocean_mixed_layer_thickness_defined_by_*
> 
> > Dear Jonathan and Sebastien,
> > 
> > 
> > 
> > 
> > I was initially thinking of not including ' _defining_mixed_layer' in my
> > suggestion and am certainly happy with leaving it out. However, I still 
> > think
> > sigma_t and sigma_theta should be prefixed with 'sea_water'. This would 
> > give:
> > 
> > 
> > 
> > 
> > 
> > sea_water_temperature_difference
> > sea_water_sigma_theta_difference
> > sea_water_sigma_t_difference
> > 
> > Cheers, Roy.
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > Please note that I partially retired on 01/11/2015. I am now only working 
> > 7.5
> > hours a week and can only guarantee e-mail response on Wednesdays, my day in
> > the office. All vocabulary queries should be sent to enquir...@bodc.ac.uk.
> > Please also use this e-mail if your requirement is urgent.
> > 
> > 
> > 
> > From: CF-metadata <cf-metadata-boun...@cgd.ucar.edu> on behalf of Jonathan
> > Gregory <j.m.greg...@reading.ac.uk>
> > Sent: 05 April 2018 18:28
> > To: cf-metadata@cgd.ucar.edu
> > Subject: Re: [CF-metadata] how to use 
> > ocean_mixed_layer_thickness_defined_by_*
> > Dear Sebastien
> > 
> > It's interesting that this question hasn't been raised before. Thanks for 
> > doing
> > so now. I agree that new standard names would be appropriate. There are 
> > already
> > some standard names containing "difference" in various ways. I would suggest
> > that for your purpose the names don't have to be so specific. You could use
> > sea_water_temperature_difference
> > sigma_theta_difference
> > sigma_t_difference
> > because in the context of your use of them it is obvious what difference you
> > mean. That would make these names perhaps useful for other purposes too. 
> > This
> > is like the rather generic name
> > air_temperature_threshold
> > which doesn't indicate what the threshold can be used for. I would also 
> > suggest
> > that the definitions of the three kinds of mixed layer depth should have a
> > sentence added to say that the threshold should be stored in a coordinate 
> > var,
> > e.g. like the sentence for 
> > number_of_days_with_air_temperature_above_threshold.
> > 
> > Best wishes
> > 
> > Jonathan
> > 
> > ----- Forwarded message from Sebastien Villaume 
> > <sebastien.villa...@ecmwf.int>
> > -----
> > 
> >> Date: Thu, 5 Apr 2018 13:55:50 +0000
> >> From: Sebastien Villaume <sebastien.villa...@ecmwf.int>
> >> To: CF Metadata <cf-metadata@cgd.ucar.edu>
> >> Subject: Re: [CF-metadata] how to use
> >> ocean_mixed_layer_thickness_defined_by_*
> >> X-Mailer: Zimbra 8.6.0_GA_1200 (ZimbraWebClient - FF52 
> >> (Linux)/8.6.0_GA_1200)
> >> 
> >> Hi all,
> >> 
> >> It seems that my question did not attract much response. :(
> >> 
> >> Is it because no one knows how to use these standard names and properly 
> >> encode
> >> the "quantity that differs from its surface value by a certain amount"?
> >> 
> >> Giving it more thoughts I feel that I need new standard names to describe 
> >> this
> >> properly.
> >> 
> >> Would it make sense to describe it this way:
> >> 
> >> float swtd ;
> >> swtd:standard_name = "sea_water_temperature_difference_wrt_sea_surface" ;
> >> swtd:units = "degC" ;
> >> swtd:axis = "Z" ;
> >> swtd:positive = "down" ;
> >> swtd:long_name = "temperature difference wrt its surface value"
> >> 
> >> float omlt(t, j, i) ;
> >> omlt:standard_name = "ocean_mixed_layer_thickness_defined_by_temperature" ;
> >> omlt:units = "m" ;
> >> omlt:coordinates = "time swtd1 latitude longitude" ;
> >> omlt:long_name = "ocean mixed layer defined by difference of temperature 
> >> from
> >> surface"
> >> 
> >> and the scalar value swtd can be 0.5 degC, 1.0 degC, etc.
> >> 
> >> In this case, I need standard names working with temperature, sigma_theta 
> >> and
> >> sigma_t:
> >> 
> >> sea_water_temperature_difference_wrt_sea_surface
> >> sigma_theta_difference_wrt_sea_surface
> >> sigma_t_difference_wrt_sea_surface
> >> 
> >> 
> >> any quick suggestions are very welcome!
> >> 
> >> thanks
> >> /Sébastien
> >> 
> >> ----- Original Message -----
> >> > From: "Sebastien Villaume" <sebastien.villa...@ecmwf.int>
> >> > To: "CF Metadata" <cf-metadata@cgd.ucar.edu>
> >> > Sent: Wednesday, 4 April, 2018 14:04:42
> >> > Subject: [CF-metadata] how to use 
> >> > ocean_mixed_layer_thickness_defined_by_*
> >> 
> >> > Dear list,
> >> > 
> >> > I have a question regarding the use of the standard names of the form
> >> > ocean_mixed_layer_thickness_defined_by_*
> >> > 
> >> > the definition from the official standard name 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 or
> >> > sigma_theta is the level at which the quantity indicated differs from its
> >> > surface value by a certain amount."
> >> > 
> >> > From what I understand, in the case of
> >> > ocean_mixed_layer_thickness_defined_by_temperature, I should specify some
> >> > quantity as a scalar (Z axis), but it is actually a temperature 
> >> > difference that
> >> > I need to encode, not a plain temperature : temp_surf - temp_base_level =
> >> > temp_delta_defining_mixed_layer_thickness
> >> > 
> >> > if it was simply a temperature I would maybe use:
> >> > 
> >> > float swpt ;
> >> > swpt:standard_name = "sea_water_potential_temperature" ;
> >> > swpt:units = "degC" ;
> >> > swpt:axis = "Z" ;
> >> > swpt:positive = "down" ;
> >> > 
> >> > but what I really want to encode is a temperature difference. How can I 
> >> > specify
> >> > that? Is "sea_water_potential_temperature" the correct standard name to 
> >> > use?
> >> > 
> >> > 
> >> > same question for ocean_mixed_layer_thickness_defined_by_sigma_theta, 
> >> > how do I
> >> > encode a "difference" in sigma_theta?
> >> > 
> >> > thanks,
> >> > 
> >> > ____________________________________
> >> > 
> >> > Dr. Sébastien Villaume
> >> > 
> >> > M.A.R.S. Analyst
> >> > ECMWF Data Governance facilitator
> >> > 
> >> > ECMWF
> >> > Shinfield Park,
> >> > Reading RG2 9AX, UK
> >> > +44 (0)118 949 9301
> >> > +44 (0)7825 521592
> >> > sebastien.villa...@ecmwf.int
> >> > ____________________________________
> >> > _______________________________________________
> >> > CF-metadata mailing list
> >> > CF-metadata@cgd.ucar.edu
> >> > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
> > 
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> > and proposals for extensions or change to the CF conventions.
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> > 
> > ----- End forwarded message -----
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