[CF-metadata] how to represent a "pft" dimension

From: Etienne Tourigny <etourigny.dev>
Date: Wed, 13 Jun 2012 16:31:59 -0300

On Wed, Jun 13, 2012 at 4:23 PM, Jonathan Gregory
<j.m.gregory at reading.ac.uk> wrote:
> Dear Etienne
>
>> The problem with area_type is that it mostly deals with "vegetation
>> types" rather than "plant function types", some models make a
>> distinction between them.
>> For example, a "savanna" vegetation type is made of several "plant
>> function types", such as grass, shrubs and deciduous trees
>
> I would see no objection to adding some PFTs to the area_type table. They
> can be area types too, of course i.e. you could have an area covered by
> grass or shrubs.

I would rather see something like actual land cover types, such as the
IGBP classification:

---
Water
Evergreen Needleleaf forest
Evergreen Broadleaf forest
Deciduous Needleleaf forest
Deciduous Broadleaf forest
Mixed forest
Closed shrublands
Open shrublands
Woody savannas
Savannas
Grasslands
Permanent wetlands
Croplands
Urban and built-up
Cropland/Natural vegetation mosaic
Snow and ice
Barren or sparsely vegetated
---
As I mentioned earlier, some land surface/ vegetation models represent
a particular surface type (say savanna) as a combination of different
PFTs (such as grass, shrubs, trees, etc).
As many models can have different PFTs, depending on their complexity,
I don't see an advantage in making a standard name table for  this,
because its use would be limited.
Although, if the list is comprehensive enough, it should be sufficient
for all needs
>
>> Numeric values are easier to deal with in many models, and also in
>> displaying (e.g. in grads)
>
> Yes, I appeciate that. If you use flag_values and flag_meanings, you can
> have a data variable with numerical values, and it's still self-describing
> because the flag attributes record a "key" to translate the numbers into
> strings.
Ok, I will look into that
Thanks,
Etienne
>
> Best wishes
>
> Jonathan
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Received on Wed Jun 13 2012 - 13:31:59 BST