Dear CF Board,
I wish to close the loop on this subject held a few weeks back, in which
I proposed amending the definition
to the standard name, atmosphere_optical_thickness_due_to_cloud, by
introducing the following clarification
sentence:
"Cloud" means the component of extinction owing to the presence of
liquid or ice water particles.
John Graybeal affirmed this proposal, but I am not sure if this is
considered to still be an open issue. John raised
an excellent point, questioning if 'cloud' should be considered to be a
process. Perhaps this can be circumvented
by amending the last sentence to read:
The quantity named may be considered a single term in a sum of terms
which, together, compose the general quantity,
atmosphere_optical_thickness.
Thus, removing the concept of a process, altogether.
Sincerely,
Gary Meehan
On 12/19/2013 1:59 PM, John Graybeal wrote:
> All of this makes sense to me.
>
> It prompts me to ask: Is 'cloud' actually a process? Or should the
> standard due_to definition clause be updated to include process or
> substance?
>
> John
>
> On Dec 19, 2013, at 09:49, Gary Meehan <gmeehan at aer.com
> <mailto:gmeehan at aer.com>> wrote:
>
>> Dear CF board,
>>
>> I would like to close the loop on a question posed this past April
>> pertaining to the definition associated with the standard name,
>> atmosphere_optical_thickness_due_to_cloud. At the time, it was
>> observed by the original poster that the definition of this standard
>> name does not make a connection to the presence of cloud contributing
>> to the atmosphere optical thickness quantity. As a result, it was
>> proposed that the definition of this standard name be amended by
>> introducing the sentence "Cloud means the component
>> of extinction owing to the presence of liquid or ice water
>> particles." The definition of this standard name, in its entirety,
>> would thus read as follows:
>>
>> The optical thickness is the integral along the path of radiation of
>> a volume scattering/absorption/attenuation coefficient.
>> The radiative flux is reduced by a factor exp(-optical_thickness) on
>> traversing the path. A coordinate variable of radiation_wavelength
>> or radiation_frequency can be specified to indicate that the optical
>> thickness applies at specific wavelengths or
>> frequencies. The atmosphere optical thickness applies to radiation
>> passing through the entire atmosphere. *"Cloud" means
>> the component of extinction owing to the presence of liquid or ice
>> water particles.* The specification of a physical
>> process by the phrase due_to_process means that the quantity named is
>> a single term in a sum of terms which together
>> compose the general quantity named by omitting the phrase.
>>
>> The goal of re-posting this question to the Board is to inquire if it
>> feels that an update to the definition is warranted, and if
>> the proposed wording is thus acceptable. Updating the definition in
>> this manner would make it consistent with the definitions
>> of the other atmosphere_optical_thickness_due_to_<process> standard
>> names.
>>
>> Sincerely,
>>
>> Gary
>> --
>> Gary Meehan
>> Senior Staff Scientist
>> Atmospheric and Environmental Research
>> 131 Hartwell Avenue, Lexington, MA 02421-3126
>> Tel (781) 761-2228 ? Fax (781) 761-2299
>> e-mail:gmeehan at aer.com
>> _______________________________________________
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>
> ------------------------------------
> *John Graybeal*
> Sr. Data Manager, Metadata & Semantics
>
> M +1 408 675-5445
> skype: graybealski
> Marinexplore
> 920 Stewart Drive
> Sunnyvale 94085
> California, USA
> www.marinexplore.com <http://marinexplore.com>
>
--
Gary Meehan
Senior Staff Scientist
Atmospheric and Environmental Research
131 Hartwell Avenue, Lexington, MA 02421-3126
Tel (781) 761-2228 ? Fax (781) 761-2299
e-mail: gmeehan at aer.com
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