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 <[email protected]> ----- > Date: Mon, 13 May 2013 18:01:03 -0400 > From: Ted Kennelly <[email protected]> > To: Jonathan Gregory <[email protected]> > CC: [email protected] > 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 > >[email protected] > >http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > > ----- End forwarded message ----- _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
