Russ and all,
One aspect of netCDF-4 we almost certainly expect to make use of for
CMIP6 is the "automated" compression option. As far as I know, this
does not affect the conventions. If you see a problem with this, please
let me know right away.
Karl
lem any
On 9/10/14, 9:16 AM, Russ Rew wrote:
Jim,
I'm hoping more data providers follow your approach, as it will
gradually bring along software developers, other data providers, and
ultimately conventions authors. I gave a talk
<http://www.unidata.ucar.edu/presentations/Rew/agu_2010_nc4_Rew.pdf>
at AGU a few years back about how to manage the transition to the
netCDF-4 enhanced data model. The obstacles to the transition are
summarized in slides 19-21, where my lack of artistic talent is
demonstrated in an illustration of the "chicken and egg logjam".
--Russ
On Wed, Sep 10, 2014 at 9:25 AM, Jim Biard <[email protected]
<mailto:[email protected]>> wrote:
Tim,
You can use netCDF-4 without "classic" format, but for true, full
CF compliance you can't use any new features.
Personal opinion alert!!! The following is just my personal
opinion. I'm not trying to stir up trouble. I'm just sharing my
observations on my experiences. Please don't hate me.
The official CF community position is that for
backwards-compatibility reasons, they would rather not adopt new
features unless there is no "good" workaround using the old
feature set. Contention can arise over the question of whether you
view the workaround as "good" or not, but that seems to be roughly
how the thought goes. The CF community also do not view themselves
as developers of new features that aren't driven by present needs.
They are also interested in maximizing the ability of (sometimes
theoretical) existing CF-aware analysis packages to properly
handle all CF-compliant files.
In previous conversations I've been given to understand that the
effective process for bringing new netCDF features into CF will be
for someone to use them in a dataset, doing their best to
interpret CF in the light of the new features. If it is a popular
dataset, it will push the CF community towards adopting some form
of those new features.
In a case where I was developing a new dataset that would have
been particularly unwieldy (in my opinion) without groups, I went
ahead and used them, applying a hierarchical scope approach to
file and group attributes. As my dataset is not likely to be
widely used by any analysis packages, it will not likely cause
anyone grief or drive the adoption of new netCDF features into CF.
Grace and peace,
Jim
On 9/10/14, 9:53 AM, Timothy Patterson wrote:
Is it correct to say that, although they don't explicitly state it, the CF
conventions (1.6 and the draft 1.7) restrict compliant netCDF products to be
either netCDF-3 or netCDF-4 in classic format? There are no conventions for the
enhanced features such as groups and user-defined types like enumerated
variables, and Section 2.2, as an example, bars the use of unsigned integer
variables or string variables (which are even stated not to exist, again
implying classic-model only).
There are some features of the enhanced model we want to use for our future
datasets (such as groups) and some features which would make life easier but
could be worked around if it led to CF compliance (enumerated types, unsigned
integers, string types, etc.). Are there any plans to introduce conventions for
the use of these enhanced features at some point in the future or would
non-classic model datasets always be seen as non-compliant?
Thanks for your insights on this issue!
Regards,
Tim Patterson
---------------------
Dr. Timothy Patterson
Instrument Data Simulation
Product Format Specification
EUMETSAT, Eumetsatallee 1, D-64295 Darmstadt, Germany
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