Re: [CF-metadata] new standard_name needed for cloud_phase (an enumeration type) - GOES-R

[alison.pamment]

Dear Michael,

Thank you for your reply - I will update the definition of the existing name as 
discussed. I am just about to start the standard name table update and this 
change will be included.

Hopefully we can finalise the remaining six GOES-R names in time for the next 
update which will take place in September.

Best wishes,
Alison

--
Alison Pamment Tel: +44 1235 778065
Centre for Environmental Data Analysis Email: 
alison.pamm...@stfc.ac.uk<mailto:j.a.pamm...@rl.ac.uk>
STFC Rutherford Appleton Laboratory
R25, 2.22
Harwell Oxford, Didcot, OX11 0QX, U.K.


From: CF-metadata [mailto:cf-metadata-boun...@cgd.ucar.edu] On Behalf Of 
Carlomusto, Michael
Sent: 07 July 2015 16:45
To: cf-metadata@cgd.ucar.edu
Subject: Re: [CF-metadata] new standard_name needed for cloud_phase (an 
enumeration type) - GOES-R



On 7 July 2015 - Reply by Mike Carlomusto:

Alison,
I agree with your assessment - the proposed standard name 
"cloud_phase_category" and the existing standard name 
thermodynamic_phase_of_cloud_water_particles_at_cloud_top are redundant.

Your proposed addition of three values - clear_sky, super_cooled_liquid_water 
and unknown - to thermodynamic_phase_of_cloud_water_particles_at_cloud_top is 
an excellent solution and acceptable for the GOES-R Cloud Top Phase product.
Mike



On 3 July 2015 Alison Pamment wrote:



> Thread "new standard_name needed for cloud_phase (an enumeration

> type)"

> (http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2013/056424.html)

>

> Current status: Under discussion.

> cloud_phase_category (canonical units: 1) 'Cloud phase category is a

> string, taking one of the following standardised values: clear_sky,

> liquid_water, super_cooled_liquid_water, mixed_phase, ice, unknown.

> For a data variable it is encoded as an integer using flag_values and 
> flag_meanings.'

>



> This name received some brief discussion on the mailing list and was

> agreed at the time. However, I was looking through existing names

> whose definitions also refer to flag_values and flag_meanings because

> I wanted to check that the wording of the proposed definition is

> broadly consistent.  In doing so I came across the name

> thermodynamic_phase_of_cloud_water_particles_at_cloud_top, introduced

> into the standard name table at Version 24 (June 2013), for use with

> Meteosat Second Generation (MSG) data. The existing name is defined as

> follows:

> ' "cloud_top" refers to the top of the highest cloud. "Water" means

> water in all phases. A variable with the standard name of

> thermodynamic_phase_of_cloud_water_particles_at_cloud_top contains

> integers which can be translated to strings using flag_values and

> flag_meanings attributes. Alternatively, the data variable may contain

> strings which indicate the thermodynamic phase. These strings are

> standardised. Values must be chosen from the following list: liquid;

> ice; mixed.'

>

> Although the list of standardised values is not the same as proposed

> for GOES-R, I think the existing name is basically the same quantity

> as the one requested. My suggestion is that, instead of adding the new

> name, we expand the definition of the existing name to allow for all

> the strings needed for both MSG and GOES-R data, as follows:



> ' "cloud_top" refers to the top of the highest cloud. "Water" means

> water in all phases. A variable with the standard name of

> thermodynamic_phase_of_cloud_water_particles_at_cloud_top contains

> integers which can be translated to strings using flag_values and

> flag_meanings attributes. Alternatively, the data variable may contain

> strings which indicate the thermodynamic phase. These strings are

> standardised. Values must be chosen from the following list: liquid;

> ice; mixed; clear_sky; super_cooled_liquid_water; unknown.'

>

> The standardised strings for liquid_water and mixed_phase would be

> slightly different from those agreed in the discussion of the current

> proposal, but if the names are to be combined I think we would need to

> stick with the earlier strings so as not to invalidate existing MSG data.

> Expanding the list of standardised strings would not affect existing

> data as I don't think there is any requirement to use all possible

> values of flag_values and flag_meanings within a particular data

> variable. One of the reasons for using standard names in CF is to

> avoid accidental duplication of quantities with the same meaning but

> different names, so I think that expanding the existing definition is the 
> right way to go. Do you agree?

Michael Carlomusto
mcarl...@harris.com<mailto:mcarl...@harris.com>
Harris Corp.
Government Communications Systems Division (GCSD), GOES-R Ground System
Melbourne, FL, USA
(321) 309-7905

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Re: [CF-metadata] new standard_name needed for cloud_phase (an enumeration type) - GOES-R

[Carlomusto, Michael]

On 7 July 2015 - Reply by Mike Carlomusto:

Alison,
I agree with your assessment - the proposed standard name 
"cloud_phase_category" and the existing standard name 
thermodynamic_phase_of_cloud_water_particles_at_cloud_top are redundant.

Your proposed addition of three values - clear_sky, super_cooled_liquid_water 
and unknown - to thermodynamic_phase_of_cloud_water_particles_at_cloud_top is 
an excellent solution and acceptable for the GOES-R Cloud Top Phase product.
Mike



On 3 July 2015 Alison Pamment wrote:



> Thread "new standard_name needed for cloud_phase (an enumeration

> type)"

> (http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2013/056424.html)

>

> Current status: Under discussion.

> cloud_phase_category (canonical units: 1) 'Cloud phase category is a

> string, taking one of the following standardised values: clear_sky,

> liquid_water, super_cooled_liquid_water, mixed_phase, ice, unknown.

> For a data variable it is encoded as an integer using flag_values and 
> flag_meanings.'

>



> This name received some brief discussion on the mailing list and was

> agreed at the time. However, I was looking through existing names

> whose definitions also refer to flag_values and flag_meanings because

> I wanted to check that the wording of the proposed definition is

> broadly consistent.  In doing so I came across the name

> thermodynamic_phase_of_cloud_water_particles_at_cloud_top, introduced

> into the standard name table at Version 24 (June 2013), for use with

> Meteosat Second Generation (MSG) data. The existing name is defined as

> follows:

> ' "cloud_top" refers to the top of the highest cloud. "Water" means

> water in all phases. A variable with the standard name of

> thermodynamic_phase_of_cloud_water_particles_at_cloud_top contains

> integers which can be translated to strings using flag_values and

> flag_meanings attributes. Alternatively, the data variable may contain

> strings which indicate the thermodynamic phase. These strings are

> standardised. Values must be chosen from the following list: liquid;

> ice; mixed.'

>

> Although the list of standardised values is not the same as proposed

> for GOES-R, I think the existing name is basically the same quantity

> as the one requested. My suggestion is that, instead of adding the new

> name, we expand the definition of the existing name to allow for all

> the strings needed for both MSG and GOES-R data, as follows:



> ' "cloud_top" refers to the top of the highest cloud. "Water" means

> water in all phases. A variable with the standard name of

> thermodynamic_phase_of_cloud_water_particles_at_cloud_top contains

> integers which can be translated to strings using flag_values and

> flag_meanings attributes. Alternatively, the data variable may contain

> strings which indicate the thermodynamic phase. These strings are

> standardised. Values must be chosen from the following list: liquid;

> ice; mixed; clear_sky; super_cooled_liquid_water; unknown.'

>

> The standardised strings for liquid_water and mixed_phase would be

> slightly different from those agreed in the discussion of the current

> proposal, but if the names are to be combined I think we would need to

> stick with the earlier strings so as not to invalidate existing MSG data.

> Expanding the list of standardised strings would not affect existing

> data as I don't think there is any requirement to use all possible

> values of flag_values and flag_meanings within a particular data

> variable. One of the reasons for using standard names in CF is to

> avoid accidental duplication of quantities with the same meaning but

> different names, so I think that expanding the existing definition is the 
> right way to go. Do you agree?

Michael Carlomusto
mcarl...@harris.com
Harris Corp.
Government Communications Systems Division (GCSD), GOES-R Ground System
Melbourne, FL, USA
(321) 309-7905

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Re: [CF-metadata] new standard_name needed for cloud_phase (an enumeration type)

[Randy Horne]

Jonathan:

Answering your questions…

(1)
clear_sky instead of clear is fine.

(2)
super_cooled_liquid_water is a subset of liquid_water.

Thus, the definition you have suggested for:

standard_name: cloud_phase_category

with definition:

The variable is a string, taking one of the following values to indicate
cloud phase category: clear_sky, liquid_water, super_cooled_liquid_water,
mixed_phase, ice, unknown. For a data variable it is encoded as an integer
using flag_values and flag_meanings.


is fine.

very respectfully,

randy


On Apr 19, 2013, at 8:22 AM, Jonathan Gregory wrote:

> Dear Randy
> 
>> We are planning on using flags with numeric values as you suggest  Your 
>> input is helpful in that is is deemed unnecessary to specifically identify 
>> values in the definition as is the case with the binary_masks,  This 
>> provides additional flexibility to data producers.
> 
> Yes, exactly.
> 
>> standard_name: cloud_phase_category
>> 
>> definition:
>> 
>> A numeric value indicating one of the following categories: clear; liquid 
>> water; super-cooled liquid water; mixed phase; ice, and; unknown.
> 
> But it would be a string-valued quantity in principle, although netCDF does 
> not
> allow string-valued data variables. I think the definition should say
> 
> The variable is a string, taking one of the following values to indicate
> cloud phase category: clear_sky, liquid_water, super_cooled_liquid_water,
> mixed_phase, ice, unknown. For a data variable it is encoded as an integer
> using flag_values and flag_meanings.
> 
> Comments on the values:
> 
> * clear_sky is a phrase already used in standard names. Could you use it
> here for consistency?
> 
> * Is super_cooled_liquid_water a subset of liquid_water? If not, could you
> give an extra adjective to liquid_water to clarify this?
> 
> Cheers
> 
> Jonathan
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Randy C. Horne (rho...@excaliburlabs.com)
Principal Engineer, Excalibur Laboratories Inc.
voice & fax: (321) 952.5100
url: http://www.excaliburlabs.com





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Re: [CF-metadata] new standard_name needed for cloud_phase (an enumeration type)

[Jonathan Gregory]

Dear Randy

> We are planning on using flags with numeric values as you suggest  Your input 
> is helpful in that is is deemed unnecessary to specifically identify values 
> in the definition as is the case with the binary_masks,  This provides 
> additional flexibility to data producers.

Yes, exactly.

> standard_name: cloud_phase_category
> 
> definition:
> 
> A numeric value indicating one of the following categories: clear; liquid 
> water; super-cooled liquid water; mixed phase; ice, and; unknown.

But it would be a string-valued quantity in principle, although netCDF does not
allow string-valued data variables. I think the definition should say

The variable is a string, taking one of the following values to indicate
cloud phase category: clear_sky, liquid_water, super_cooled_liquid_water,
mixed_phase, ice, unknown. For a data variable it is encoded as an integer
using flag_values and flag_meanings.

Comments on the values:

* clear_sky is a phrase already used in standard names. Could you use it
here for consistency?

* Is super_cooled_liquid_water a subset of liquid_water? If not, could you
give an extra adjective to liquid_water to clarify this?

Cheers

Jonathan
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Re: [CF-metadata] new standard_name needed for cloud_phase (an enumeration type)

[Randy Horne]

Jonathan:

We are planning on using flags with numeric values as you suggest  Your input 
is helpful in that is is deemed unnecessary to specifically identify values in 
the definition as is the case with the binary_masks,  This provides additional 
flexibility to data producers.

Revising the proposal per your recommendation …

standard_name: cloud_phase_category

definition:

A numeric value indicating one of the following categories: clear; liquid 
water; super-cooled liquid water; mixed phase; ice, and; unknown.


very respectfully,

randy


On Apr 19, 2013, at 5:59 AM, Jonathan Gregory wrote:

> Dear Randy
> 
> There is another way to do it, which makes the files more self-describing and
> has been suggested for other similar situations. You could instead define the
> standard_name for a new string-valued quantity such as cloud_phase_category,
> but store the data in the file in numeric form using flag_values and
> flag_meanings.  Then you don't have to standardise the actual numbers used.
> I suppose that the permitted strings should be part of the definition of the
> standard name (instead of defined numerical values). 
> 
> Best wishes
> 
> Jonathan
> 
> - Forwarded message from "rho...@excaliburlabs.com" 
>  -
> 
>> From: "rho...@excaliburlabs.com" 
>> To: cf-metadata@cgd.ucar.edu
>> Date: Thu, 18 Apr 2013 18:05:09 -0400
>> Subject: [CF-metadata] new standard_name needed for cloud_phase (an
>>  enumeration type)
>> 
>> 
>> 
>> Folks:   The GOES-R ground system is generating a cloud phase quantity.  
>> This is derived from the imager aboard the geostationary satellite.   The 
>> quantity can take on six  value (i.e. it is an categorical / enumeration 
>> type) where each value defines a different cloud phase category - Clear(0), 
>> liquid water(1), super-cooled liquid water(2), mixed phase(3), ice(4), 
>> unknown(5). I looked through the current CF standard_name table and 
>> could not find any enumeration types other than the binary_masks. Here 
>> is a first cut at a proposal that generally follows the existing 
>> binary_mask standard_names: standard_name: cloud_phase_category
>> definition: X_category has six categories where 0=clear, 1=liquid water, 
>> 2=super-cooled liquid water, 3=mixed phase, 4=ice, and 5=unknown. very 
>> respectfully,   randy 
> 
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> 
> 
> - End forwarded message -
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Randy C. Horne (rho...@excaliburlabs.com)
Principal Engineer, Excalibur Laboratories Inc.
voice & fax: (321) 952.5100
url: http://www.excaliburlabs.com





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