Dear Alison,
Thanks for looking into this. I am happy with the name and definition.
Regards,
Alejandro
> -----Original Message-----
> From: alison.pamment at stfc.ac.uk [mailto:alison.pamment at stfc.ac.uk]
> Sent: 02 March 2016 17:40
> To: Bodas-Salcedo, Alejandro; cf-metadata at cgd.ucar.edu
> 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: alison.pamment at stfc.ac.uk
> STFC Rutherford Appleton Laboratory
> R25, 2.22
> Harwell Campus, Didcot, OX11 0QX, U.K.
>
>
>
> > -----Original Message-----
> > From: CF-metadata [mailto:cf-metadata-bounces at cgd.ucar.edu] On Behalf
> > Of Bodas-Salcedo, Alejandro
> > Sent: 20 January 2016 09:37
> > To: cf-metadata at cgd.ucar.edu
> > 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:cf-metadata-bounces at cgd.ucar.edu] On
> > Behalf Of
> > > Markus Fiebig
> > > Sent: 19 January 2016 12:49
> > > To: cf-metadata at cgd.ucar.edu
> > > 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: Markus.Fiebig at nilu.no
> > > skype: markus.fiebig
> > >
> > > P Please consider the environment before printing this email and
> > attachments
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Received on Thu Mar 03 2016 - 03:37:05 GMT
