Dear CF list, I took a bit longer to write down the proposed definitions of these 3 standard names.
standard name: sea_water_temperature_difference units: K description: Sea water temperature is the in situ temperature of the sea water. The standard name "sea_water_temperature_difference" can be used (as an auxiliary coordinate) together with the standard name "ocean_mixed_layer_thickness_defined_by_temperature" to define its temperature criterion. standard name: sea_water_sigma_theta_difference units: kg/m3 description: Sigma-theta of sea water is the potential density (i.e. the density when moved adiabatically to a reference pressure) of water having the same temperature and salinity, minus 1000 kg m-3. The standard name "sea_water_sigma_theta_difference" can be used (as an auxiliary coordinate) together with the standard name "ocean_mixed_layer_thickness_defined_by_sigma_theta" to define its sigma_theta criterion. standard name: sea_water_sigma_t_difference units: kg/m3 description: Sigma-t of sea water is the density of water at atmospheric pressure (i.e. the surface) having the same temperature and salinity, minus 1000 kg m-3. The standard name "sea_water_sigma_t_difference" can be used (as an auxiliary coordinate) together with the standard name "ocean_mixed_layer_thickness_defined_by_sigma_t" to define its sigma_t criterion. Alternatively, we could move the last sentence of each description to the respective "ocean_mixed_layer_thickness_defined_by_*" standard names to make that specific usage more explicit. We then keep a more general description for the new "*_difference" standard names. /Sébastien ----- Original Message ----- > From: "Jonathan Gregory" <j.m.greg...@reading.ac.uk> > To: "Sebastien Villaume" <sebastien.villa...@ecmwf.int> > Cc: cf-metadata@cgd.ucar.edu, "Lowry, Roy K." <r...@bodc.ac.uk> > Sent: Friday, 6 April, 2018 14:24:18 > Subject: Re: [CF-metadata] how to use > ocean_mixed_layer_thickness_defined_by_* > 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 >> > >> > >> > CF-metadata Info Page - mailman.cgd.ucar.edu >> > mailman.cgd.ucar.edu >> > This is an unmoderated list for discussions about interpretation, >> > clarification, >> > and proposals for extensions or change to the CF conventions. >> > >> > >> >> _______________________________________________ >> >> CF-metadata mailing list >> >> CF-metadata@cgd.ucar.edu >> >> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata >> > >> > ----- End forwarded message ----- >> > _______________________________________________ >> > CF-metadata mailing list >> > CF-metadata@cgd.ucar.edu >> > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata >> > >> > This message (and any attachments) is for the recipient only. 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