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
>> > ____________________________________
>> > _______________________________________________
>> > CF-metadata mailing list
>> > CF-metadata at cgd.ucar.edu
>> > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
>
>
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Received on Thu Apr 05 2018 - 13:04:26 BST
