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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