Hello CF-ers,
Background:
The topic of this message is the the CF Standard Names
table. But the context is considerably broader than CF
users, alone. The value of the CF conventions already
extends well beyond the climate and forecast modeling
communities. CF represents one of the most mature and
thoughtful profiles of netCDF that exists today. As such it
has great deal of value to other communities. As an
example, I have encouraged the international group working
on developing an OTS standard (Ocean Time Series -- for
moored ocean measurements) to adopt as much of CF as they
can. A time series series is after all just a degenerate 4D
grid, right? Much of CF applies very nicely. Importantly
it is an achievable goal that an OTS data set can *be* a CF
dataset simply by defining some new attributes and
conventions that are mandatory for OTS, only. So any CF
application will be able to read OTS files -- even if some
of the specialized semantics are not understood.
One notable flaw in this is the CF standard_name table. The
"standard_name" attribute is highly applicable to the OTS
(or any other) community. But the CF standard_name table
contents are not. The ocean measurement community needs to
grow its own rapidly evolving and distinct list of
specialized names -- some may be as arcane and specialized
as "tendency_of_air_temperature_due_to_diabatic_processes".
I assert (in order to hear if there is dissent) that CF does
not want to become a naming authority for all physical
parameters. CF is already having to juggle compatibility
with many other organizations involved in this game.
Proposal:
I propose the following new tag, "standardNameConventions":
// global attributes:
:Conventions = "CF-1.0" ;
:standardNameConventions =
?
http://www.cgd.ucar.edu/cms/eaton/cf-metadata/standard_name.xml?
The goal is to make CF into a broader standard at little
effort -- so that OTS and other communities can create true
CF files with differing parameter name standards. Other
communities could insert their own standard_name.xml file.
The new attribute will also liberate the CF standard, so
that the name table can evolve separately from the CF
version, itself (and much more rapidly.)
- steve
====
Post Scriptum:
Standard name tables will be evolving documents for some
time to come (for ever). Mistakes will be made in official
versions of the table (make no mistake about it!) There
should be a mechanism to correct mistakes without "breaking"
files that have previously been created. For discussion I
propose that an easy means to achieve this might be to
expand the XML schema of the standard name table with just a
few new tags, so that it can become an audit trail. In
other words add new XML tags (in bold below) such as
<standardNameTableVersion>
<versionNumber>1.2</versionNumber>
<date>22Jun2004</date>
</standardNameTableVersion>
and
<renamed id="air_pressure_at_convective_cloud_base"
version=1.2>
xlink to new and old <entry> tags
</renamed>
and
<entry id="new_air_pressure_at_convective_cloud_base">
<version>1.2</version>
<canonical_units>Pa</canonical_units>
<description>cloud_base refers to the base of the lowest
cloud.</description>
</entry>
and even
<deleted id="some_misbegotten_variable" version=1.2>
xlink to old <entry> tag
</renamed>
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Received on Tue Jun 22 2004 - 18:14:39 BST
