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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Received on Tue Jan 25 2011 - 18:04:30 GMT
