Dear Sebastien I would favour your alternative > 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. for the reason you give, which appeals to me.
Also, instead of "auxiliary coordinate" I would say "coordinate variable or scalar coordinate variable". A scalar coord var is formally like a size-one auxiliary coord var. However the threshold variable could in principle be multi-valued; then you'd have a dimension for it, and it wouldn't be an aux coord var. Best wishes Jonathan ----- Forwarded message from Sebastien Villaume <[email protected]> ----- > Date: Tue, 10 Apr 2018 10:36:21 +0000 (GMT-00:00) > From: Sebastien Villaume <[email protected]> > To: [email protected] > Cc: "Lowry, Roy K." <[email protected]>, Jonathan Gregory > <[email protected]> > 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) > > > 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" <[email protected]> > > To: "Sebastien Villaume" <[email protected]> > > Cc: [email protected], "Lowry, Roy K." <[email protected]> > > 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 <[email protected]> > >> To: [email protected] > >> Cc: Jonathan Gregory <[email protected]>, "Lowry, Roy K." > >> <[email protected]> > >> 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." <[email protected]> > >> > To: [email protected], "Jonathan Gregory" > >> > <[email protected]> > >> > 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 > >> > [email protected]. > >> > Please also use this e-mail if your requirement is urgent. > >> > > >> > > >> > > >> > From: CF-metadata <[email protected]> on behalf of > >> > Jonathan > >> > Gregory <[email protected]> > >> > Sent: 05 April 2018 18:28 > >> > To: [email protected] > >> > 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 > >> > <[email protected]> > >> > ----- > >> > > >> >> Date: Thu, 5 Apr 2018 13:55:50 +0000 > >> >> From: Sebastien Villaume <[email protected]> > >> >> To: CF Metadata <[email protected]> > >> >> 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" <[email protected]> > >> >> > To: "CF Metadata" <[email protected]> > >> >> > 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 > >> >> > [email protected] > >> >> > ____________________________________ > >> >> > _______________________________________________ > >> >> > CF-metadata mailing list > >> >> > [email protected] > >> >> > 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 > >> >> [email protected] > >> >> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > >> > > >> > ----- End forwarded message ----- > >> > _______________________________________________ > >> > CF-metadata mailing list > >> > [email protected] > >> > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > >> > > >> > This message (and any attachments) is for the recipient only. NERC is > >> > subject to > >> > the Freedom of Information Act 2000 and the contents of this email and > >> > any > >> > reply you make may be disclosed by NERC unless it is exempt from release > >> > under > >> > the Act. Any material supplied to NERC may be stored in an electronic > >> > records > >> > management system . > >> > > >> > _______________________________________________ > >> > CF-metadata mailing list > >> > [email protected] > > > > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata ----- End forwarded message ----- _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
