Dear Alison, Thanks for looking into this. I am happy with the name and definition.
Regards, Alejandro > -----Original Message----- > From: [email protected] [mailto:[email protected]] > Sent: 02 March 2016 17:40 > To: Bodas-Salcedo, Alejandro; [email protected] > Subject: RE: [CF-metadata] New standard name for aerosol single scattering > albedo > > Dear Alejandro and Markus, > > Just picking up on Alejandro's proposal. I like the suggestion of > single_scattering_albedo_in_air_due_to_ambient_aerosol_particles (canonical > units:1 (dimensionless)). > This is indeed consistent with the syntax of existing names. The > "due_to_ambient_aersol_particles" phrase should be understood to mean that the > scattering is indeed due to the particulate component of the aerosol and not > the > surrounding air. We have standard definition text that should make all that > clear: > ' "Single scattering albedo" is the fraction of radiation in an incident > light beam > scattered by the particles of an aerosol reference volume for a given > wavelength. It > is the ratio of the scattering and the extinction coefficients of the aerosol > particles in > the reference volume. A coordinate variable with a standard name of > radiation_wavelength or radiation_frequency should be included to specify > either the > wavelength or frequency. "Aerosol" means the system of suspended liquid or > solid > particles in air (except cloud droplets) and their carrier gas, the air > itself. > "Ambient_aerosol" means that the aerosol is measured or modelled at the > ambient > state of pressure, temperature and relative humidity that exists in its > immediate > environment. "Ambient aerosol particles" are aerosol particles that have > taken up > ambient water through hygroscopic growth. The extent of hygroscopic growth > depends on the relative humidity and the composition of the particles. To > specify the > relative humidity and temperature at which the quantity described by the > standard > name applies, provide scalar coordinate variables with standard names of > "relative_humidity" and "air_temperature". 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.' > > Alejandro, if you are happy with this then I think the name can be accepted > for > inclusion in the standard name table. > > Best wishes, > Alison > > ------ > Alison Pamment Tel: +44 > 1235 778065 > Centre for Environmental Data Analysis Email: > [email protected] > STFC Rutherford Appleton Laboratory > R25, 2.22 > Harwell Campus, Didcot, OX11 0QX, U.K. > > > > > -----Original Message----- > > From: CF-metadata [mailto:[email protected]] On Behalf > > Of Bodas-Salcedo, Alejandro > > Sent: 20 January 2016 09:37 > > To: [email protected] > > Subject: Re: [CF-metadata] New standard name for aerosol single scattering > > albedo > > > > Dear Markus, > > > > Thanks for your comment. I'm happy with the change to a population of > > particles. As you say, it's a more practical definition. I find the first > > sentence > > a bit difficult, though. What about the following? > > > > > > Definition: Fraction of radiation in an incident light beam scattered by the > > particles of an aerosol reference volume as a function of wavelength. It is > > the ratio of the scattering and the extinction coefficients of the aerosol > > particles in the reference volume. A coordinate of radiation_wavelength or > > radiation_frequency should be included to specify either the wavelength or > > frequency. > > > > Regarding the humidity state, perhaps we should follow the definition for > > the extinction coefficient, and use the name > > > > single_scattering_albedo_in_air_due_to_ambient_aerosol_particles > > > > My only reservation is that this seems to refer to the optical properties of > > aerosols plus the molecular atmosphere, not only aerosols. > > > > Regards, > > > > Alejandro > > > > > > > -----Original Message----- > > > From: CF-metadata [mailto:[email protected]] On > > Behalf Of > > > Markus Fiebig > > > Sent: 19 January 2016 12:49 > > > To: [email protected] > > > Subject: Re: [CF-metadata] New standard name for aerosol single > > scattering albedo > > > > > > Dear Alejandro, > > > > > > after reading your mail, I was surprised to realise that > > > aerosol_single_scattering_albedo in fact hadn't been defined yet. > > > > > > However, the definition you propose seems to me rather unusual. You > > define the > > > single scattering albedo with respect to a single particle as ratio of > > > cross-sections, i.e. as truly microscale property. From the multitude of > > > particles contained in an aerosol, how do you determine which particle > > you refer to? > > > > > > From my experience, it's more usual to define the single scattering albedo > > as > > > ratio of scattering and extinction coefficient of a particle population, > > > i.e. > > an > > > effective property for the ensemble of particles contained in the aerosol. > > How > > > about this: > > > > > > Definition: Fraction of radiation in an incident light beam interacting > > > with > > the > > > particles of an aerosol reference volume and scattered by these particles > > as a > > > function of wavelength. It is the ratio of the scattering and the > > > extinction > > > coefficients of the aerosol particles in the reference volume. A > > > coordinate > > of > > > radiation_wavelength or radiation_frequency should be included to > > specify either > > > the wavelength or frequency. > > > > > > Having said that, should we also consider to include the humidity state of > > the > > > aerosol? That would require relative_humidity as additional coordinate > > variable. > > > > > > Best regards, > > > Markus > > > > > > Am 19.01.2016 um 10:47 schrieb Bodas-Salcedo, Alejandro: > > > > Dear All, > > > > > > > > I'd like to propose a new standard name, which as far as I can see > > > > doesn't > > > currently exist in the CF table: > > > > > > > > Name: aerosol_single_scattering_albedo > > > > Units: 1 > > > > Description: Fraction of radiation scattered out of a pencil of > > > > radiation > > after one > > > encounter with an aerosol particle for a given wavelength. It is the ratio > > between the > > > scattering cross-section and the extinction cross-section. A coordinate of > > > radiation_wavelength or radiation_frequency should be included to > > specify either the > > > wavelength or frequency. > > > > > > > > > > > > Thanks, > > > > > > > > Alejandro > > > > > > > > > > -- > > > Dr. Markus Fiebig > > > Senior Scientist > > > Dept. Atmospheric and Climate Research (ATMOS) > > > Norwegian Institute for Air Research (NILU) > > > P.O. Box 100 > > > N-2027 Kjeller > > > Norway > > > > > > Tel.: +47 6389-8235 > > > Fax : +47 6389-8050 > > > e-mail: [email protected] > > > skype: markus.fiebig > > > > > > P Please consider the environment before printing this email and > > attachments > > _______________________________________________ > > CF-metadata mailing list > > [email protected] > > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
