[CF-metadata] New standard name for aerosol single scattering albedo

From: Bodas-Salcedo, Alejandro <alejandro.bodas>
Date: Wed, 20 Jan 2016 09:37:09 +0000

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
Received on Wed Jan 20 2016 - 02:37:09 GMT