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: [email protected]
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