Dear Philip and Alison,
Philip: Thanks for your valuable comment. This discussion started in
November and has been revived last week.
Alison, I think based on Philips comment we can exclude the two standard
names which use the defined_by suffix. What do you think?
(I thought that these defined_by suffixes were a good way to
differentiate between these physical quantities...)
>> In your case above, it appears to me that there is only one physical quantity, thermodynamic_phase_of_cloud_water_particles_at_cloud_top, but multiple ways to try and measure it (that may give different answers because of errors and limitations of the measurements).
Do you have suggestions on how we could differentiate between these
variables in a CF compatible way? In our MSG CPP NetCDF files, should we
use the same standard_name for the two different variables?
When we use a viewer like IDV for example, how can we see the difference
between these variables? I have never tried this in IDV, so I don't know
what happens in this case... That is way we would like to have
distinguishable standard names.
Best regards,
Maarten
PS, the new list:
- platform_zenith_angle; degree
- angle_of_rotation_from_solar_azimuth_to_platform_azimuth; degree
- thickness_of_liquid_water_cloud; m
- effective_radius_of_cloud_condensed_water_particles_at_cloud_top; m
- thermodynamic_phase_of_cloud_water_particles_at_cloud_top; 1
On 01/26/2011 02:04 AM, Cameron-smith, Philip wrote:
> Hi Maarten,
>
> Sorry for this last minute reply (I don't think this was addressed before). My comment relates to the following proposed names:
>
> - thermodynamic_phase_of_cloud_water_particles_at_cloud_top (status_flag liquid, ice and mixed): "The thermodynamic phase of particles at the top of the cloud";
> - thermodynamic_phase_of_cloud_water_particles_at_cloud_top_defined_by_infrared_radiance
> (status_flag liquid, ice and mixed): "The thermodynamic phase of particles at the top of the cloud derived by using infrared radiances";
> - thermodynamic_phase_of_cloud_water_particles_at_cloud_top_defined_by_near_infrared_radiance
> (status_flag liquid, ice and mixed):" The thermodynamic phase of particles at the top of the cloud derived by using near-infrared radiances".
>
> It appears that your use of 'defined_by' may be different than that currently used by other std_names in CF.
>
> Specifically, 'defined_by' is currently used for ocean_mixed_layer_thickness, which can be different depending on which physical quantity is used to diagnose it (eg, ocean_mixed_layer_thickness_defined_by_temperature, ocean_mixed_layer_thickness_defined_by_vertical_tracer_diffusivity). To me, each of these is a different physical quantity.
> I presume the same would apply to the atmospheric boundary layer and the tropopause.
>
> In your case above, it appears to me that there is only one physical quantity, thermodynamic_phase_of_cloud_water_particles_at_cloud_top, but multiple ways to try and measure it (that may give different answers because of errors and limitations of the measurements).
>
> Following standard CF practice I think only thermodynamic_phase_of_cloud_water_particles_at_cloud_top should be added as a std_name.
>
> The only argument I can see for making these different physical quantities is that the definition of 'cloud_top' presumably differs a bit for each wavelength. Personally I doubt that the difference is great enough to warrant different std_names, but please correct me if I'm wrong :-). And if this does warrant different std_names, then the wavelengths will need to be clearly specified.
>
> Best wishes,
>
> Philip
>
> -----------------------------------------------------------------------
> Dr Philip Cameron-Smith, pjc at llnl.gov, Lawrence Livermore National Lab.
> -----------------------------------------------------------------------
>
>
>> -----Original Message-----
>> From: cf-metadata-bounces at cgd.ucar.edu [mailto:cf-metadata-
>> bounces at cgd.ucar.edu] On Behalf Of alison.pamment at stfc.ac.uk
>> Sent: Monday, January 24, 2011 6:03 AM
>> To: cf-metadata at cgd.ucar.edu; plieger at knmi.nl
>> Subject: Re: [CF-metadata] MSG Cloud physical properties codification
>>
>> Dear Maarten and Jonathan,
>>
>> Maarten has reminded me that the following names were discussed a few
>> weeks ago:
>>
>> - platform_zenith_angle (degree): "Platform zenith angle is the the
>> angle between the line of sight to the platform and the local
>> vertical";
>> - angle_of_rotation_from_solar_azimuth_to_platform_azimuth (degree):
>> "The angle of rotation between the solar azimuth angle and the platform
>> azimuth angle";
>> - thickness_of_liquid_water_cloud (m): "Cloud thickness (cloud top
>> height minus cloud base)";
>> - effective_radius_of_cloud_condensed_water_particles_at_cloud_top (m):
>> "Particle effective radius for both liquid and ice water particles";
>> - thermodynamic_phase_of_cloud_water_particles_at_cloud_top
>> (status_flag liquid, ice and mixed): "The thermodynamic phase of
>> particles at the top of the cloud";
>> -
>> thermodynamic_phase_of_cloud_water_particles_at_cloud_top_defined_by_in
>> frared_radiance
>> (status_flag liquid, ice and mixed): "The thermodynamic phase of
>> particles at the top of the cloud derived by using infrared radiances";
>> -
>> thermodynamic_phase_of_cloud_water_particles_at_cloud_top_defined_by_ne
>> ar_infrared_radiance
>> (status_flag liquid, ice and mixed):" The thermodynamic phase of
>> particles at the top of the cloud derived by using near-infrared
>> radiances".
>>
>> I think these names all follow the pattern of existing names and their
>> meanings are generally clear. One question - in your products, are
>> 'infrared' and 'near_infrared' separate ranges of
>> wavelengths/frequencies? Please could you tell me the ranges so that I
>> can include at least indicative values in the explanations of the
>> names. For the three status flag names, I suggest that the units
>> should be '1', i.e. a dimensionless value, assuming that the variables
>> will be accompanied by flag_values and flag_meanings attributes. If we
>> can clarify these points then I think the names can be accepted for
>> inclusion in the standard name table.
>>
>> Best wishes,
>> Alison
>>
>> ------
>> Alison Pamment Tel: +44 1235 778065
>> NCAS/British Atmospheric Data Centre Fax: +44 1235 446314
>> STFC Rutherford Appleton Laboratory Email:
>> alison.pamment at stfc.ac.uk
>> R25, 2.22
>> Harwell Oxford, Didcot, OX11 0QX, U.K.
>>
>>
>> From: cf-metadata-bounces at cgd.ucar.edu [mailto:cf-metadata-
>> bounces at cgd.ucar.edu] On Behalf Of Maarten Plieger
>> Sent: 30 November 2010 16:49
>> To: Jonathan Gregory
>> Cc: cf-metadata at cgd.ucar.edu
>> Subject: Re: [CF-metadata] MSG Cloud physical properties codification
>>
>> Dear Jonathan,
>>
>> Good point. That is OK with us, off course. Thanks again!
>>
>> Regards, Maarten
>>
>> Jonathan Gregory schreef:
>> Dear Maarten
>>
>> Yesterday I didn't notice that these don't have _radiance on the end. I
>> think
>> that would make them clearer, if OK with you.
>>
>>
>> thermodynamic_phase_of_cloud_water_particles_at_cloud_top_defined_by_in
>> frared
>> thermodynamic_phase_of_cloud_water_particles_at_cloud_top_defined_by_ne
>> ar_infrared
>>
>> When everybody agrees with these standard names, units and
>> descriptions:
>> what would be the next step?
>>
>> Alison will consider them. She is responsible for moderating
>> discussions and
>> updating the standard name table with agreed additions.
>>
>> Best wishes
>>
>> Jonathan
>>
>>
>>
>>
>> --
>> Maarten Plieger
>> KNMI, R&D Information and Observation Technology, De Bilt
>> (t) +31 30 2206330
>> --
>> Scanned by iCritical.
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>
--
Maarten Plieger
KNMI, R&D Information and Observation Technology, De Bilt
(t) +31 30 2206330
Received on Wed Jan 26 2011 - 04:39:48 GMT
