Dear Jonathan,
>> -> _atmosphere or _in_atmosphere?
You suggest to change the postifx in_atmosphere into the prefix
atmosphere. I like the idea, in case it does not conflict with the
medium/component concept, see below.
>
> I agree that atmosphere means not-ocean etc. It is a "component" in the
> guidelines.
I do not understand why you say that "atmosphere" is a "component".
Components are defined in the "Guidelines for Construction of CF
Standard Names" as
"
Component
The direction of the spatial component of a vector is indicated by one
of the words upward, downward, northward, southward, eastward, westward,
x, y. The last two indicate directions along the horizontal grid being
used when they are not true longitude and latitude (if there is a
rotated pole, for instance).
If the standard name indicates a tensor quantity, two of these direction
words may be included, applying to two of the spatial dimensions Z Y X,
in that order. If only one component is indicated for a tensor, it means
the flux in the indicated direction of the magnitude of the vector
quantity in the plane of the other two spatial dimensions.
The names of vertical components of radiative fluxes are prefixed with
net_, thus: net_downward and net_upward. This treatment is not applied
for any kinds of flux other than radiative. Radiative fluxes from above
and below are often measured and calculated separately, the "net" being
the difference. Within the atmosphere, radiation from below (not net) is
indicated by a prefix of upwelling, and from above with downwelling. For
the top of the atmosphere, the prefixes incoming and outgoing are used
instead.
"
> The standard names for "atmosphere" are properties of the atmos
>> as a whole. I assume that the "medium" in_air means a local measurement
>> in air, regardless of whether it is in a cloudy or a cloud-free region.
I agree, in_air means in_gasphase, therefore, there can be clouds or
not, but the conentration/mass fraction is referring to the gas phase.
By contrast (in_)atmosphere would be regardless of clouds, as far as I
thought.
The in_something qualifier matches the "medium" definition of the
guidelines. "Atmosphere" would also be a medium in this sense, but
rather a large scale, not a local one. Maybe large scale media like
atmosphere
toa
surface
ocean
etc.
could be a prefix and small scale media a postfix?
> I suggest that the right way to distinguish these in CF
> would be with cell_methods, as they are different parts of the gridbox. We
> already have cloud and clear_sky as area_types, so you can specify
> e.g. "area: mean where cloud" in cell_methods for an in_air quantity to
> restrict it to the cloudy air.
I do not think that this is a good idea as some species change the state
when dissolved in water, e.g. so2->h2so3->->... i think it is essential
to have the medium as part of the standard name for quantities that are
very different. This would fit in the concept that the names in the CF
conventions should be easily human-understandable.
> Perhaps clear-sky isn't the best choice, as that refers to a 2D view of the
> atmosphere. As these area-types are new, it maybe wouldn't be too late to
> change it, for instance to cloud_free.
The expression 'clear_sky' is only used for radiative properties, and
there 'assuming_clear_sky' is used, which I think is very clear, I would
rather suggest to keep it.
> Quantities measured in precipitation, not in air, are a new medium, I suppose.
> Do you need to name such quantities?
Yes, I think we will do, there a many observations for example on the
composition of rain.
Best wishes
Christiane
======================================================================
Dr Christiane Textor
Laboratoire des Sciences du Climat et de l'Environnement
Unite Mixte de Recherche CEA-CNRS-UVSQ
LSCE/IPSL, CEA Saclay, Orme des Merisiers,
Bat. 701, Piece 3b, Point Courrier 129
F-91191 Gif-sur-Yvette Cedex
FRANCE
mailto: christiane.textor at lsce.ipsl.fr
Tel ++33 1 69 08 34 07 Fax ++33 1 69 08 77 16
GEOmon scientific coordinator
http://www.geomon.eu
======================================================================
Received on Sun Nov 23 2008 - 10:15:39 GMT
