Thanks, Maarten. Do you want to propose a definition for Albedo from the
TROPOMI Algorithm Team document? What I find there is:
/Albedo: The ratio: outgoing irradiance / incoming irradiance. This
//is in contrast
to the reflectance which is the ratio: outgoing radiance / incoming
irradiance.
/That doesn't stand alone, in my opinion, and would need to include the
TROPOMI
definitions for the supporting terms (or at least for irradiance):/
Radiance: radiative energy density in a particular direction.
Ir///radiance: /the integral of the radiance weighted with m over 2p
steradians.
/
There are 2 possible problems with this that I can see. First, Karl said:
> the proposed definition of albedo doesn't mention that the photons
> included in the calculation are emitted by the sun. Radiation
> originating at the surface or in the atmosphere ("longwave"), is not
> included in the fluxes considered.
This doesn't seem to be addressed by the TROPOMI definition. I hate to start
mucking around with it, but could the term '/outgoing irradiance' /be
replaced
by/'//r//eflected/ /irradiance/' to answer this point?
Second CF contains this definition for irradiance, inside the
solar_irradiance definition:
/"Irradiance" means the power per unit area (called radiative flux in
other standard
names), the area being normal to the direction of flow of the radiant
energy./
Ian Grant suggested this:
/Albedo is the ratio of the radiant flux exiting a reference surface
into the whole hemisphere //
//to the radiant flux incident on the same surface from the hemisphere.
The albedo, also called //
//the bihemispherical reflectance, is often the ratio of upwelling flux
to downwelling flux at a //
//horizontal surface, such as the reflected and incident radiation at an
interface./
Any specific suggestion on a definition based on the document (or on
anything else)?
Cheers - Nan
On 8/20/15 1:22 PM, Maarten Sneep wrote:
> On 10/08/15 19:37, Maarten Sneep wrote:
>> On 07/08/15 21:15, Nan Galbraith wrote:
>>> Hi All, and happy Friday.
>>>
>>> It's been almost a month since Maarten Sneep posted 'A few
>>> definitions seem off'
>>> and there have been just a couple of replies.
>>>
>>> Can we please add definitions for albedo and air_pressure to the
>>> standard names
>>> table? Do people think we don't need these defined - is that the
>>> problem?
>>>
>>> I have no particular preference about the content of the
>>> definitions, here's what's
>>> been proposed.
>>
>> We have a document with definitions we use for our remote sensing
>> work. This document
>> is currently in the signatures loop, but I hope to share it with you
>> in the coming
>> week. That gives at least our definitions, from a perspective of a
>> group that is
>> strictly looking in the short-wave spectrum. Note that the document
>> uses maths to
>> define the quantities, which is a bit awkward for the textual
>> definitions used in CF.
>> But at least it can provide a basis, for quite some quantities. Also
>> note that there
>> are quantities defined in the document that would be nice in CF from
>> our perspective,
>> but I don't feel like 'defending' them here (a slant column, anyone?).
>
> Here is the list of terms & definitions we use for satellite remote
> sensing development at KNMI. I hope you find this useful.
>
> Best,
>
> Maarten Sneep
>
>
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--
*******************************************************
* Nan Galbraith Information Systems Specialist *
* Upper Ocean Processes Group Mail Stop 29 *
* Woods Hole Oceanographic Institution *
* Woods Hole, MA 02543 (508) 289-2444 *
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