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.
/S?bastien
----- Original Message -----
> From: "Jonathan Gregory" <j.m.gregory at reading.ac.uk>
> To: "Sebastien Villaume" <sebastien.villaume at ecmwf.int>
> Cc: cf-metadata at cgd.ucar.edu, "Lowry, Roy K." <rkl at 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.villaume at ecmwf.int>
>> To: cf-metadata at cgd.ucar.edu
>> Cc: Jonathan Gregory <j.m.gregory at reading.ac.uk>, "Lowry, Roy K."
>> <rkl at 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!
>>
>> /S?bastien
>>
>> ----- Original Message -----
>> > From: "Lowry, Roy K." <rkl at bodc.ac.uk>
>> > To: cf-metadata at cgd.ucar.edu, "Jonathan Gregory" <j.m.gregory at 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 enquiries at bodc.ac.uk.
>> > Please also use this e-mail if your requirement is urgent.
>> >
>> >
>> >
>> > From: CF-metadata <cf-metadata-bounces at cgd.ucar.edu> on behalf of Jonathan
>> > Gregory <j.m.gregory at reading.ac.uk>
>> > Sent: 05 April 2018 18:28
>> > To: cf-metadata at 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.villaume at ecmwf.int>
>> > -----
>> >
>> >> Date: Thu, 5 Apr 2018 13:55:50 +0000
>> >> From: Sebastien Villaume <sebastien.villaume at ecmwf.int>
>> >> To: CF Metadata <cf-metadata at 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
>> >> /S?bastien
>> >>
>> >> ----- Original Message -----
>> >> > From: "Sebastien Villaume" <sebastien.villaume at ecmwf.int>
>> >> > To: "CF Metadata" <cf-metadata at 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. S?bastien 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.villaume at ecmwf.int
>> >> > ____________________________________
>> >> > _______________________________________________
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>> >> > CF-metadata at cgd.ucar.edu
>> >> > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
>> >
>> >
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>> >
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>> > ----- End forwarded message -----
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Received on Tue Apr 10 2018 - 04:36:21 BST
