Hi all -
I thought I should re-post this with a more clear subject line, in case
anyone else wants to to weigh in on the definitions, or lack
thereof, of albedo and air pressure.
Are these self-describing enough that they don't need to be
defined in CF? Or should we add at least a minimal definition?
Thanks -
Nan
On 7/14/15 3:22 PM, Nan Galbraith wrote:
> Thanks for raising this, Maarten; we should fix the albedo
> definitions. I use
> surface_albedo regularly, but didn't actually have a definition handy,
> so went
> googling.
>
> This one's from wikipedia:
>
> Albedo is the ratio of reflected radiation from the surface to incident
> radiation upon it. Its dimensionless nature lets it be expressed as a
> percentage and is measured on a scale from zero for no reflection of
> a perfectly black surface to 1 for perfect reflection of a white surface.
>
> This one's from ESR.org (earth and space research) and is narrower,
> specific
> to earth's surface:
>
> Albedo is the fraction of solar energy (shortwave radiation) reflected
> from
> the Earth back into space. It is a measure of the reflectivity of the
> earth's
> surface.
>
> I propose we could add the sentence 'Albedo is the ratio of reflected
> radiation from
> the surface to incident radiation upon it' - or something similar - to
> all 3 albedo
> definitions.
>
> For air_pressure_at_cloud_top, well, the definition of air_pressure is
> 'No help available.'
> so I guess that's a problem.
>
> If we use sea_water_pressure as an example, here's that definition:
> '"Sea water pressure" is
> the pressure that exists in the medium of sea water.' True enough.
>
> Cheers - Nan
>
>
> On 7/10/15 10:47 AM, Maarten Sneep wrote:
>> Hi,
>>
>> I came across a few descriptions in the standard name list that seem
>> 'off', or clearly unclear.
>>
>> surface_albedo: "The surface called "surface" means the lower
>> boundary of the atmosphere." (this doesn't define albedo itself).
>>
>> planetary_albedo: "No help available."
>>
>> cloud_albedo: "The albedo of cloud." (this doesn't define albedo
>> itself either, and is not very specific).
>>
>> air_pressure_at_cloud_top: "cloud_top refers to the top of the
>> highest cloud." (This apears very much a modelled parameter, not a
>> parameter from some remote sensing technique. Either the description
>> is kept deliberately vague, or I miss something. It is hard to use
>> this description on observations).
>>
>> I'm sure there are more, but these caught my eye. I'm not sure how to
>> change the descriptions, I don't know the history of these quantities
>> in the standard name list. Can someone advise how to proceed?
>>
>> Best,
>>
>> Maarten Sneep
>
>
--
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* Nan Galbraith Information Systems Specialist *
* Upper Ocean Processes Group Mail Stop 29 *
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Received on Fri Jul 17 2015 - 12:24:38 BST
