Dear John and Karl,
Thanks for your comments about the changes.
John Graybeal wrote:
>
> I have a few suggestions for the area_type info. Well, more like
> questions.
>
> An area_type that I imagine being useful within a year or two, if not
> within months, is the benthic floor (i.e., land under the sea). And
> by analog: land under a lake, or the more general
> water_covered_ground. I'm not recommending those changes now, but they
> raise the following question: Is 'land' is intended to be all-
> encompassing in this regard? Definitions would help make this clear.
My own understanding of 'land' is that it means dry land, i.e. not
covered by seas. I think essentially it corresponds to those areas that
would be flagged as land in the land-sea mask of a climate model. I
have wondered myself if this definition of 'land' actually includes
lakes and rivers. I'd welcome any suggestions as to what the precise
definition should be.
> As a general observation, discussing terms without associated
> definitions can lead to confusion on all parts.
I couldn't agree more! It is often only when I come to write the
definitions of standard names that I realise just how woolly is my own
understanding of some of the concepts involved. I would very much like
to move to a situation where all area_type strings and all
standard_names have help text associated. The reasons that very few
area_types have descriptions at the moment are: (a) none were discussed
under ticket 17; (b) I didn't want to simply invent descriptions without
having the opportunity to discuss them first; (c) we wanted to make a
first draft of the area_type table available quickly because the list is
already starting to grow and people need to get at the information.
>
> I don't see how all_standard_names makes sense as an area_type.
>
I think this is a typo and the string should in fact read
all_area_types. Thanks for pointing this out and I'm sure Velimir will
correct it shortly.
> If lake_ice_or_sea_ice excludes icebergs, does sea_ice? This is
> counterintuitive to a lay person, admittedly not the target audience.
> (Also note, this is where the relation between terms is useful
> information to have -- somewhere in my assumed hierarchy
> floating_ice
> lake_ice_or_sea_ice
> sea_ice
> there is a discrepancy, perhaps intentional. Suggest the discontinuity
> be made explicit in the definition (i..e, explain why
> lake_ice_or_sea_ice excludes icebergs, while floating_ice does not;
> and address whether sea_ice includes icebergs. The definition is
> where people will look to understand the relationships.
Again, I agree completely with your general point. I think we do need
to be clear about the definitions, or to be able to say when and why we
are being deliberately vague. Quite a number of the standard name
descriptions contain information about relationships and I can see no
reason not to do the same with area_types. As to whether sea_ice
includes icebergs, I suspect the answer is no (because climate model
sea-ice masks don't include icebergs) but my answer could well be wrong!
I hope that Jonathan may be able to help out with the ice area_types as
it is more his field of expertise than mine.
>
> I assume the absence of lake_ice is deliberate. (Just a thought:
> Sometimes completeness is helpful for clarity, especially when there
> are no definitions, even though there may not be any immediate use for
> the term. Otherwise it makes some of us wonder why something *wasn't*
> included.)
>
A lake_ice area type hasn't been included at the moment because nobody
has asked for it. The underlying philosophy for adding standard names
is that we don't add them unless there is a specific proposal, even if
that means that some obvious 'sets' of standard names are incomplete.
In the first instance I have adopted a similar philosophy for
area_types. As you know, there is a lot of discussion at the moment
about the general direction standard names should take in the future and
I suggest that would be a suitable place for further debate of this
particular point. I would note, however, that the current position is
consistent with the overall CF development philosophy of not trying to
anticipate all possible future needs.
Best wishes,
Alison
==> Please note new email address: alison.pamment at stfc.ac.uk <==
------
J Alison Pamment Tel: +44 1235 778065
NCAS/British Atmospheric Data Centre Fax: +44 1235 446314
Rutherford Appleton Laboratory Email: alison.pamment at stfc.ac.uk
Chilton, Didcot, OX11 0QX, U.K.
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Received on Fri Dec 05 2008 - 07:55:02 GMT
