Dear Ted
That looks fine to me. It'd be interesting to know if anyone else has comments.
Thanks
Jonathan
----- Forwarded message from Ted Kennelly <ekennell at aer.com> -----
> Date: Mon, 13 May 2013 18:01:03 -0400
> From: Ted Kennelly <ekennell at aer.com>
> To: Jonathan Gregory <j.m.gregory at reading.ac.uk>
> CC: cf-metadata at cgd.ucar.edu
> Subject: Re: [CF-metadata] New reflectance standard names
> User-Agent: Thunderbird 2.0.0.24 (Macintosh/20100228)
>
> Below are the updated descriptions for the two proposed standard
> names. Note CF does not seem to have a definition for albedo though
> it is used
> in a handful of standard_names.
>
> -ted
>
>
> ?toa_lambertian_equivalent_albedo?
>
> ?Albedo is the ratio of the outgoing to the incoming power per unit
> area (irradiance). A coordinate variable can be used to specify the
> radiation wavelength or frequency. ?toa? means top of atmosphere.
> ?lambertian_equivalent? means the quantity is evaluated for a
> diffusely reflecting surface.?
>
> canonical units = 1
>
>
>
>
> ?toa_lambertian_equivalent_albedo_multiplied_by_cosine_solar_zenith_angle?
>
> ?Albedo is the ratio of the outgoing to the incoming power per unit
> area (irradiance). A coordinate variable can be used to specify the
> radiation wavelength or frequency. ?toa? means top of atmosphere.
> ?lambertian_equivalent? means the quantity is evaluated for a
> diffusely reflecting surface.
> ?multiplied_by_cosine_solar_zenith_angle? means that the quantity
> has normalized to remove the angular dependence of the incoming
> shortwave irradiance?
>
> canonical units = 1
>
>
> Jonathan Gregory wrote:
> >Dear Ted
> >
> >Thanks for this explanation:
> >
> >>Reflectance is the ratio of outgoing radiance to incoming irradiance
> >>giving it units of per steradians.
> >>Albedo is the ratio of outgoing irradiance to incoming irradiance
> >>and is unitless.
> >>Because the proposed quantity is unitless, albedo is the better term.
> >>However, albedo is the integral over all angles of the bidirectional
> >>reflectance. In general, true
> >>planetary albedo would account for this angular dependence. To make clear the
> >>assumption regarding the Lambertian surface I still propose using the term
> >Lambertian equivalent in the name. Thus:
> >
> >>toa_lambertian_equivalent_albedo
> >>toa_lambertian_equivalent_albdeo_multiplied_by_cosine_solar_zenith_angle
> >
> >OK, with small L in lambertian as you had before (because stdnames are all
> >in lower case). Thanks!
> >
> >Cheers
> >
> >Jonathan
> >_______________________________________________
> >CF-metadata mailing list
> >CF-metadata at cgd.ucar.edu
> >http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
>
>
----- End forwarded message -----
Received on Sat May 18 2013 - 08:42:01 BST
