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<div class="Section1">
<h1><span lang="EN-GB" style="font-size:20.0pt"> </span></h1>
<h1 align="center" style="text-align:center"><span lang="EN-GB" style="font-size:
18.0pt">Maintaining and Advancing the CF Standard for</span></h1>
<h1 align="center" style="text-align:center"><span lang="EN-GB" style="font-size:
18.0pt"> Earth System Science Community Data</span></h1>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal" align="center" style="text-align:center"><span lang="EN-GB">B.N.
Lawrence<a href="#_ftn1" name="_ftnref1" title=""><span class="MsoFootnoteReference"><span class="MsoFootnoteReference"><span lang="EN-GB" style="font-size:12.0pt;font-family:"Times New Roman"">[1]</span></span></span></a>,
R. Drach<a href="#_ftn2" name="_ftnref2" title=""><span class="MsoFootnoteReference"><span class="MsoFootnoteReference"><span lang="EN-GB" style="font-size:12.0pt;font-family:"Times New Roman"">[2]</span></span></span></a>,
B.E. Eaton<a href="#_ftn3" name="_ftnref3" title=""><span class="MsoFootnoteReference"><span class="MsoFootnoteReference"><span lang="EN-GB" style="font-size:12.0pt;font-family:"Times New Roman"">[3]</span></span></span></a>,
J. M. Gregory<a href="#_ftn4" name="_ftnref4" title=""><span class="MsoFootnoteReference"><span class="MsoFootnoteReference"><span lang="EN-GB" style="font-size:12.0pt;font-family:"Times New Roman"">[4]</span></span></span></a>,
S. C. Hankin<a href="#_ftn5" name="_ftnref5" title=""><span class="MsoFootnoteReference"><span class="MsoFootnoteReference"><span lang="EN-GB" style="font-size:12.0pt;font-family:"Times New Roman"">[5]</span></span></span></a>,
R.K. Lowry<a href="#_ftn6" name="_ftnref6" title=""><span class="MsoFootnoteReference"><span class="MsoFootnoteReference"><span lang="EN-GB" style="font-size:12.0pt;font-family:"Times New Roman"">[6]</span></span></span></a>,
R.K. Rew<a href="#_ftn7" name="_ftnref7" title=""><span class="MsoFootnoteReference"><span class="MsoFootnoteReference"><span lang="EN-GB" style="font-size:12.0pt;font-family:"Times New Roman"">[7]</span></span></span></a>,
and K. E. Taylor<sup>2</sup>.</span></p>
<p class="MsoNormal" align="center" style="text-align:center"><span lang="EN-GB"> </span></p>
<p class="MsoNormal" align="center" style="text-align:center"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<h1><span lang="EN-GB">Abstract</span></h1>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoBlockText"><span lang="EN-GB">The Climate and Forecast (CF)
conventions governing metadata appearing in netCDF files are becoming ever more
important to earth system science communities. This paper outlines proposals
for the future of CF, based on discussions at an international meeting held at
the British Atmospheric Data Centre in 2005. The proposal presented here is
aimed at maintaining the scientific integrity of the CF conventions, while
transitioning to a community governance structure (from the current situation
where CF is maintained informally by the original authors). </span></p>
<p class="MsoBlockText"><span lang="EN-GB"> </span></p>
<h2><span lang="EN-GB">1. Introduction</span></h2>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB">The Climate and
Forecast (CF) metadata conventions are designed to promote the processing and
sharing of data stored in files created with the netCDF API<a href="#_ftn8" name="_ftnref8" title=""><span class="MsoFootnoteReference"><span class="MsoFootnoteReference"><span lang="EN-GB" style="font-size:12.0pt;font-family:
"Times New Roman"">[8]</span></span></span></a>. Fundamental features of the
conventions are that CF-aware software can automatically determine the
space-time location of variables (facilitating analysis and graphical display),
and metadata describing each variable is sufficiently detailed to determine
whether variables from different sources are comparable. The general principles
of CF design are enumerated in Gregory (2003)<a href="#_ftn9" name="_ftnref9" title=""><span class="MsoFootnoteReference"><span class="MsoFootnoteReference"><span lang="EN-GB" style="font-size:12.0pt;font-family:"Times New Roman"">[9]</span></span></span></a>:</span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<ol style="margin-top:0in" start="1" type="1">
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Data should be
self-describing. No external tables are needed to interpret the file. For
instance, CF encodings do not depend upon numeric codes (by contrast with
GRIB).</span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Conventions
have been developed only for known issues. Instead of trying to foresee
the future, features are added as required. </span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">The convention
should be easy to use, both for data-writers and users of data.</span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">The metadata
and the semantic meaning encoded through the metadata should be readable
by humans as well as easily utilized by programs. </span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Redundancy
should be minimised as much as possible (so as to reduce the chance of
errors of inconsistency when writing data).</span></li>
</ol>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB">CF was initiated
in the climate modelling community because of the lack of an adequate existing
standard (although COARDS was a good basis, with which CF remains backward
compatible). CF is becoming the de facto standard for storing outputs of
atmospheric, ocean and climate models. Interest may expand to related
"earth system" communities, but few users have thus far embraced the
full self-descriptive capabilities enabled by the CF-standard, perhaps because
software that can interpret all of this information has yet to be developed.
Furthermore, "standard names" have not yet been agreed on for certain
quantities, and in some cases the existing conventions are unsuitable or
inefficient. To avoid fragmentation of the potential user community, such
issues must be addressed more rapidly.</span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB">CF use is
growing. As CF becomes more important to a diverse range of communities, its
boundaries of applicability are being stretched, and the workload on the
original authors is growing, such that it is not possible to keep pace with
requests for extensions. There have been questions about how (and when) CF can
evolve in the future, but it is not possible to answer such questions with
confidence given the current situation where authorship of CF is a marginal
activity on top of already full workloads, with the authors’ personal interests
representing only a part of the range of the user community. Moreover the
widespread use of CF means that its development must be undertaken with great
care and proper consultation.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoBodyText"><span lang="EN-GB">This paper outlines some of the immediate
issues that the CF community is confronting, beginning with how CF transitions
to community ownership and maintenance. It is based on an extended discussion
held at the British Atmospheric Data Centre in June 2005 as part of the annual
Global Organisation for Earth System Science Portals (GO-ESSP) meeting. </span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<h2><span lang="EN-GB">2. CF Governance and Development</span></h2>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB">If CF is to
become a widely accepted community standard, it is imperative that the
community (a) takes ownership of and responsibility for the future trajectory
of the standard and (b) invests substantial resources in its development. To do
this we need first a clear definition of the boundaries of the problem (who are
the CF community?) and then to set in place a structure for governance and
development which:</span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<ul style="margin-top:0in" type="circle">
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Preserves the
existing intellectual rigor, </span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Achieves rapid
response to community requirements, and </span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Meets the
needs of as much of the community as is possible.</span></li>
</ul>
<p class="MsoNormal" style="margin-left:.25in;text-align:justify"><span lang="EN-GB"> </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB">In some
circumstances these three “what” requirements will pull in different
directions. When this happens, one of the requirements of the governance
structure is to impose a set of constraints on CF evolution that minimises this
tension. To support the requirements we also need agreement about three “how”
issues:</span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<ul style="margin-top:0in" type="circle">
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">How should CF
maintenance be funded? </span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">How should CF
be maintained from a sociological perspective? (What organizational
structures are needed?)</span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">How should CF
be maintained from a technological perspective? (What tools are needed?) </span></li>
</ul>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB">In this section
we discuss the definition of “who is the CF community” and these three “how”
issues in regard to both what we believe is achievable in the near term, and in
terms of the three “what” requirements.</span></p>
<h3 style="text-align:justify"><span lang="EN-GB">2.1 Who is the CF Community?</span></h3>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Climate
modellers initially dominated the CF community, but, recently others (e.g.,
observational communities) have seized on CF as the solution to their own
format description problems. As these communities have expressed their needs,
new problems have arisen: for example, different terminologies are used, Earth
geometry is real, rather than idealised, and standard names are needed for
“raw” instrumental measurements before they are converted to data which are
independent of the method of observation. Other problems can be anticipated,
particularly as interdisciplinary work progresses. The scope of CF standard
names, for example, will likely need to include observational biological
oceanography, atmospheric chemistry, forest-type classification, etc.</span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Given that CF
effectively consists of three sets of conventions - vocabulary management,
semantic concepts (axes, cells etc), and format specific conventions (netCDF,
for now), it is possible that different communities may wish to be involved in
different parts of the CF evolution. For example, some users of CF are only
interested in the CF standard names, storing their data in other formats
(HDF-EOS, NASA-Ames etc), although this is problematic because some parameters
need more than just the standard names to be fully described (e.g. the cell
methods attribute describes the averaging); i.e., vocabulary and concept are
not entirely separated.</span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB">For CF to fulfil
its mission as a medium of interchange for complex information, the needs of
users must be balanced with those of data producers. In addition, the input
from developers of software that can interpret and use the CF metadata
descriptions is vital. (It was noted at the GO-ESSP meetings in both 2004 and
2005 that only a subset of CF-defined metadata is interpretable and actually
used by any real software.) Furthermore, despite the name, forecasters have not
been greatly involved in developing CF.</span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB">The future of CF
will inevitably involve use in earth system models, and so the scope of CF will
need to address the requirements of a wide range of communities. Furthermore,
CF does not exist in a vacuum. There are other projects that are developing
community standards for encoding data and describing it: notably the Open
Geospatial Consortium; the WMO metadata initiatives; and controlled
vocabularies in use in other parts of the earth system science community. A
significant challenge for the CF community will be finding ways of interacting
productively with these communities. Meanwhile a working definition of the
“CF community” needs to be “those who choose to use netCDF to store earth
system data in a self describing way” even though this initially
disenfranchises those who wish to use CF conventions for other data formats.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<h3><span lang="EN-GB">2.2 Funding </span></h3>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB">There are four
basic funding mechanisms that could support the maintenance and development of
the CF conventions:</span></p>
<ol style="margin-top:0in" start="1" type="1">
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Institutional
Subscription Mechanisms: Institutions could form a consortium, funded by
membership subscription, which would fund specific activities (with the
Open Geospatial Consortium as a possible role model). </span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">National
Subscription Mechanisms: CF could be sponsored by major international
programmes (for example, the World Climate Research Programme) allowing
national funding agencies to provide support in accordance with
international commitments.</span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Benevolent
Organisations: some key interested parties could dedicate staff time to
the CF “project” as part (or all) of their normal duties. </span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Marginal
Activities: interested parties working on CF in their “spare” time. </span></li>
</ol>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<p class="MsoBodyText"><span lang="EN-GB">Currently all CF development is funded by
the fourth of these options, which means that CF development is not responsive
enough, and it is leading to untenable workloads for the key players. </span></p>
<p class="MsoBodyText"><span lang="EN-GB"> </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Questions that
have been raised concerning the first two funding approaches listed above
include:</span></p>
<ol style="margin-top:0in" start="1" type="1">
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">How would
decisions be made to deploy the funding? </span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">In the case of
the CF Consortium: who would hold the cash? Could the financial management
be separated from the scientific decision-making? </span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">How would the
CF community become involved with national programmes? </span></li>
</ol>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<p class="MsoBodyText"><span lang="EN-GB">Given the right community management
structure, a combination of funding approaches could be used, and indeed given
where CF is now, a combination of these approaches is inevitable during what
will have to be a transition phase.</span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<p class="MsoBodyText"><span lang="EN-GB">In the near future an element of funding
from benevolent organisations is expected. Expressions of commitment to
support parts of CF development have been received from Unidata, from the
Program for Climate Model Diagnosis and Intercomparison (PCMDI), and from the
NERC Centres of Atmospheric Science (NCAS): Unidata may assist with the
community interface, PCMDI will provide support for the CF development process,
and the NCAS/British Atmospheric Data Centre (BADC) will be contributing direct
support for standard name maintenance, development and evolution. However, even
with this extra support, CF will not be able to evolve as it needs, and other
funding arrangements will be necessary. Such arrangements will not be possible
without visible leadership, accountability and formal encoding of the process
of governance</span></p>
<h3><span lang="EN-GB">2.3 Management </span></h3>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB">In keeping with
the past development of the CF standard, the GO-ESSP participants strongly
favoured a continued consensus-based governance procedure. Wide participation
should be encouraged with input sought from individuals representing a variety
of disciplines, perspectives, and geographical locations. Individual influence
on CF's future should be commensurate with the value of suggestions made and
independent of funding. </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB">There is a
strong desire within the existing CF community that, regardless of funding, the
evolution of CF should be carried out with due process. Accordingly, we propose
1) that a collection of reference files, illustrating correct CF encoding and
suitable for the testing of data-reading applications be maintained at every
stage and 2) that CF modifications occur in a manner that conforms to the
following sequence: </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<ol style="margin-top:0in" start="1" type="1">
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Requests for
modification to CF are proposed to the community.</span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">A period of
community discussion is entered into, including consideration of the
relationship of CF to other standards.</span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">A provisional
resolution is described as a consensual agreement.</span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Reference
files incorporating the proposed features are produced.</span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Where the
proposed modifications have non-trivial implications for implementation in
software, trial implementations will be carried out. Trial implementations
will be tested on both existing and new versions of the CF reference
files, to check that new features can be correctly interpreted without
detriment to backwards compatibility. A public evaluation and assessment
of experiences will follow.</span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">If problems
emerge, the process is repeated from step 2; otherwise …</span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Consensus
decision is made to accept the proposed changes as provisional changes to
the standard and to advertise these changes to the community (indicating
that advanced implementers may want to begin using them).</span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Multiple
proposed changes are evaluated as a package in order to implement an
orderly version control strategy.</span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Consensus
decisions should finalise the release of new versions of CF.</span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">The test
reference files should then become part of the corpus of test data for
future revisions.</span></li>
</ol>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB">The process will
be different in detail for modifications (usually additions) to the standard
name table on the one hand, and to the CF standard on the other. The former are
more numerous, require faster turn-round, but generally do not involve wide
community debate or trial implementations; an appropriate turn-round time is
one month. For the latter, three months would be more realistic.</span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<p class="MsoBodyText"><span lang="EN-GB">We also propose the establishment of two
standing CF committees, the membership of which would be open to those with
significant interest and time to commit to taking CF forward:</span></p>
<p class="MsoBodyText"><span lang="EN-GB"> </span></p>
<p class="MsoBodyText" style="margin-left:.5in;text-indent:-.25in"><span lang="EN-GB">1.<span style="font:7.0pt "Times New Roman"">
</span></span><span lang="EN-GB">Conventions Committee, to be responsible for
developing changes to the CF standard, and to include (but not be limited to)
representatives of those who have reference implementations, who can provide
feedback on the practicality of CF initiatives and validation of tools which
wish to be described as “CF-compliant”.</span></p>
<p class="MsoBodyText" style="margin-left:.5in;text-indent:-.25in"><span lang="EN-GB">2.<span style="font:7.0pt "Times New Roman"">
</span></span><span lang="EN-GB">Standard Name Committee, to be responsible for
adding standard names to the CF convention and working towards interoperability
with other vocabulary maintainers.</span></p>
<p class="MsoBodyText"><span lang="EN-GB"> </span></p>
<p class="MsoBodyText"><span lang="EN-GB">Although CF must remain community-driven,
its continuity can only be assured if some formally established board,
responsive to community needs, assumes responsibility. Accordingly, it is also
proposed that a CF Governance Panel be established under the auspices of
relevant major international programmes, which would be expected to appoint all
or nearly all nominees to membership. The next section discusses the establishment
of such a panel.</span></p>
<p class="MsoBodyText"><span lang="EN-GB"> </span></p>
<p class="MsoBodyText"><span lang="EN-GB">In view of their responsibility to the
community, the membership of the committees will be advertised on the CF
website. The job of the committee members will be to take an active interest in
the community debate on new developments (process outlined above),
participating personally where appropriate. On behalf of the community, the
committees will take the required decisions within their respective remits by
consensus among their own membership in cases where community consensus is not
evident because public debate is inconclusive.</span></p>
<p class="MsoBodyText"><span lang="EN-GB"> </span></p>
<p class="MsoBodyText"><span lang="EN-GB">Each of the CF committees will include a
permanent funded member of staff, viz. the manager of CF standard names and the
manager of CF conventions. Both individuals must be skilled technical document
editors, as their primary duty will be the maintenance of the CF standard
documents. The latter will mostly likely be a software engineer, able to
appreciate issues involved in both data processing and models. The former needs
an understanding of modern metadata frameworks and a broad scientific interest,
since to deal with requests for new standard names (often coming from those who
are not themselves the scientists responsible for producing the data) it is
necessary to understand what the quantities are and to become familiar with the
terminology in various fields. If past experience is a guide, the development
of CF will depend largely on these two individuals, who will be the first point
of call for requests for modifications and who will carry the process forward
by their own contributions to discussions and by deploying appropriate
technology to facilitate community involvement. In particular, it will be part
of their job to provide reference files and implementations. Although the
responsibility will lie with the committees corporately, the other members will
probably have only part-time involvement and the vagaries of their individual
workloads should not be allowed to preclude timely progression of CF. The lack
of anyone with time to carry out the role of manager of CF conventions over the
last year or so, for example, has meant that several significant developments
have been agreed on the CF email list but not yet implemented in the standard
(extension to cell_methods, standard_name parameters, relation of formula_terms
and bounds, relation of forecast and validity time).</span></p>
<p class="MsoBodyText" style="margin-left:.25in"><span lang="EN-GB"> </span></p>
<p class="MsoBodyText"><span lang="EN-GB">In both committees we recommend that </span></p>
<p class="MsoBodyText" style="margin-left:.5in;text-indent:-.25in"><span lang="EN-GB" style="font-family:"Courier New"">o<span style="font:7.0pt "Times New Roman"">
</span></span><span lang="EN-GB">Insofar as possible, the principle of “no
consensus, no change” should be followed. </span></p>
<p class="MsoBodyText" style="margin-left:.5in;text-indent:-.25in"><span lang="EN-GB" style="font-family:"Courier New"">o<span style="font:7.0pt "Times New Roman"">
</span></span><span lang="EN-GB">The chair should be elected to serve for a
period of three years, although the membership should be self-selected. Where
and when possible, the secretarial function should be funded.</span></p>
<p class="MsoBodyText" style="margin-left:.5in;text-indent:-.25in"><span lang="EN-GB" style="font-family:"Courier New"">o<span style="font:7.0pt "Times New Roman"">
</span></span><span lang="EN-GB">Insofar as possible, a geographical distribution
of members should be encouraged – partly by nominating potential candidates to
self-select as required.</span></p>
<p class="MsoBodyText"><span lang="EN-GB"> </span></p>
<p class="MsoBodyText"><span lang="EN-GB">Other ad-hoc groups may be needed to
consider various issues such as those listed in the Appendix One. Such areas,
while heavily overlapping with the CF core, may involve developing branches of
CF which may initially be in conflict. Such conflicts will need to be resolved
through a community discussion at the committee level.</span></p>
<p class="MsoBodyText"><span lang="EN-GB"> </span></p>
<h3 style="text-align:justify"><span lang="EN-GB">2.4 Responsibility and
Stewardship</span></h3>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB">As outlined
above, a formal governance framework is also desirable. There are a number of
possible candidate organisations that could provide a framework, but reflecting
the history of CF, we here recommend that initially the World Climate Research
Programme's (WCRP's) Working Group on Coupled Modeling (WGCM) take formal
responsibility for CF. </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB">The WGCM and
Working Group on Numerical Experimentation (WGNE) have been established to work
together and with the international climate and weather modeling communities to
establish "an integrated approach to climate modelling in the WCRP."
Part of their charge is to promote coordinated experimentation, which requires
sharing data among centres. For the sharing of climate model output, the
format of choice has usually been netCDF, and in some recent WGCM-coordinated
projects, the CF-conventions for metadata have been adopted (e.g., simulations
in support of the IPCC's Fourth Assessment Report). </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB">The WGCM has
expressed interest in data standards for climate model output and has been kept
abreast of the CF-developments. Recent discussions at the Ninth Session of the
WGCM led to an invitation to the original CF authors to formally request
appointment of a panel that under the WGCM would provide oversight for the
governance of the CF conventions. It is therefore proposed that the WGCM
establish a CF Governance Panel charged with the following responsibilities</span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<ul style="margin-top:0in" type="disc">
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Assure the
viability and vitality of the Conventions Committee and the Standard Name
Committee by: </span></li>
<ul style="margin-top:0in" type="circle">
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Formally
appointing members from those self-nominated and by periodically
reviewing the membership (this would also provide at least some formal
recognition of the voluntary work done by committee members).</span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Making
changes to the terms of reference of the committees by consensus with the
committee membership. </span></li>
</ul>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Promote and
help integrate CF across WCRP programs and the broader programs of WCRP's
sponsors (ICSU, WMO, and IOC). In particular the panel would attempt to
influence developing WMO metadata standards so that they gracefully
accommodate the CF conventions. Promotion of CF within other communities
would also be expected as community demand and representation grows.</span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Encourage
continued support of CF by benevolent organizations, guide the deployment
of such spending, and explore additional funding mechanisms as required. </span></li>
</ul>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB">The WGCM will
appoint members of the panel, which would specifically include (but not
necessarily be limited to<a href="#_ftn10" name="_ftnref10" title=""><span class="MsoFootnoteReference"><span class="MsoFootnoteReference"><span lang="EN-GB" style="font-size:12.0pt;font-family:"Times New Roman"">[10]</span></span></span></a>)
representatives from: 1) the WGCM, 2) the leaders, or their nominees, of groups
(initially PCMDI and NCAS) contributing significant resources in support of CF,
and 3) the chairs of the Conventions Committee and Standard Name Committee
described in section 2.3 above. Although this panel would be responsible for
stewardship of CF, it would not have any special responsibility for or
influence on its technical content. The terms of reference for the CF
Governance Panel appear in Appendix Two.</span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">As CF usage widens, it may be necessary to
consider alternative parent bodies (to the WGCM) for the CF Governance Panel,
to provide alternative funding strategies and/or better represent community
expectations of governance. Accordingly, both the WGCM and CF panel will
regularly review whether other governance strategies would be more effective.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<h2><span lang="EN-GB">3. Next Steps</span></h2>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoBodyText"><span lang="EN-GB">The two main priorities in the near
future are to spread the load of CF management by making better use of
technology (including website, issue tracking etc) to exploit the existing
in-kind contributions, and to agree upon a strategy for establishing longer
term funding stream to support CF activities. The WGCM's CF Governance Panel
needs to be established. At the same time, the community needs to buy into the
future management structures outlined here (or suggest alternatives). The
GO-ESSP meeting proposed a formal timetable to achieve that buy-in and move
from the current situation to a new community managed framework:</span></p>
<ol style="margin-top:0in" start="1" type="1">
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Community
discussion should follow the appearance of this paper (done).</span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">One month
after this paper appears, community discussion closes, and the existing CF
authors decide whether the community response requires a different
approach from that outlined here. (Done, approved)</span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">A committee
structure based on section 2.3 should be set up with initial chairs
selected by the existing CF authors. Potential members should be invited
to nominate themselves for appointment by majority vote of the CF authors
and committee chairs. .</span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">The first
order of business of the new committees should be to define the changes in
content for CF-1.1 and outline the priorities for further work.</span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">The managers
of CF standard names and conventions should be appointed as soon as
funding has been secured. (Done)</span></li>
<li class="MsoNormal" style="text-align:justify"><span lang="EN-GB">The draft
terms of reference for the committees (Appendix Two) have been approved at
a community meeting in June 2006, but would need to be formally approved
by the incoming CF Governance Panel.</span></li>
</ol>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Throughout this
process, interested parties should lobby any or all national or international
bodies that could provide ongoing funding for CF maintenance and development.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<h2><span lang="EN-GB">Appendix One: </span><span lang="EN-GB">Current and Future
Issues for CF</span></h2>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB">There are a
large number of issues which need addressing in the near future, some of which
have the potential for requiring divergence in the CF conventions, and this is
partly why an effective CF governance structure is needed.</span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB">Issues include:</span></p>
<p class="MsoNormal" style="text-align:justify"><span lang="EN-GB"> </span></p>
<ol style="margin-top:0in" start="1" type="1">
<li class="MsoNormal" style="text-align:justify"><b><span lang="EN-GB">Supporting
technology: </span></b><span lang="EN-GB">To help facilitate CF development,
several suggestions have been made, including: 1) i</span><span lang="EN-GB">ntegrating the mailing list with forum software to allow better
development of discussion threads; 2) assigning version numbers to the
evolving conventions to indicate both major and minor changes; 3)
updating and improving the website, including documentation of the reasons
for any changes or additions to the CF conventions; 4) developing further
rudimentary tools to check for CF compliance and to encourage "best
practices".</span></li>
<li class="MsoNormal" style="text-align:justify"><b><span lang="EN-GB">Staggered
and unstructured grids</span></b><span lang="EN-GB">: While the CF
convention supports storing data on staggered grids, and indeed on
irregularly spaced grids, it does it in a rather simple manner which
permits the data to be used by any software - this is an advantage - but
does not record any high-level information about the “construction” of the
grids. This is not fully supportive of the wide range of new grids which
are being proposed (e.g. the Yin/Yang grid) and may make efficient storage
of the data relatively awkward. Proposals now on the table suggest for the
first time that grid information may need to be stored in different files
from that of the data which, while not strictly in accord with CF’s status
as a netCDF convention, may be needed for practical reasons and is an
approach already supported by some software. There is also an increasing
need to describe unstructured hydrodynamic and watershed models which use
meshes consisting of triangles, quadrilaterals and mixtures of polygons.
Different issues arise, such as how to describe the indexing methods and
connectivity of meshes, and there is a wealth of experience within the
structures developed by engineering community to draw upon</span></li>
<li class="MsoNormal" style="text-align:justify"><b><span lang="EN-GB">GIS
information content: </span></b><span lang="EN-GB">Interoperability
experiments are underway in a number of places, aiming to both deliver
netCDF data into Geographical Information Systems (GIS) and to store data
originating from GIS systems in netCDF. In both cases there are technical
issues to resolve about how to deal with differing standard descriptions
and how they map onto the other.</span></li>
<li class="MsoNormal" style="text-align:justify"><b><span lang="EN-GB">Ontologies and
nomenclature: </span></b><span lang="EN-GB">CF parameters are fully
described by supplementing their standard names with additional
descriptive information stored as attributes of the netCDF variables.<b> </b>Other
ontologies categorise their information differently, e.g. by including coordinate
information (such as “1.5 above the surface” or “daily maximum”) as part
of the parameter description (in some case CF does this too, such as for
named levels such as “surface”and “top of the atmosphere”). Such
differences complicate the establishment of equivalence tables. Existing
standard names identify only those quantities normally produced or
inferred from climate models; measured parameters (such as radar signal
strength) are currently not supported. It has been suggested that CF
could exploit the XML namespace concept to allow parameters to be included
from named and linked external vocabularies (or dictionaries) which would
help with extending the domain of CF. Such external vocabularies would
have to be well managed, comprehensive, and have reliable futures to avoid
risks associated with, incomplete, imprecise or duplicate definitions and
atrophy. Where CF might come to depend on external vocabularies, it would
be important to have establish clear understandings between external
vocabulary maintainers and the CF community on how the sets of
vocabularies would evolve. <b> </b>CF could also investigate the concept
of “scope” for standard names, to allow regionally important standard
names without global agreement – this would of course have to be done with
care to avoid fragmentation.</span></li>
<li class="MsoNormal" style="text-align:justify"><b><span lang="EN-GB">NetCDF-4</span></b><span lang="EN-GB">: CF-1.0 is based on the netCDF-3 data model, and to some
extent reflects the limitations of that model. netCDF-4 introduces an
expanded model, allowing, for instance, for ragged dimensions and
hierarchical groups of data. The CF-1.0 data model will remain compatible
with netCDF-4; however, it may be more natural to express some features of
CF using the expanded model. Is it appropriate or necessary to assume the
netCDF-4 data model in subsequent revisions of CF?</span></li>
<li class="MsoNormal" style="text-align:justify"><b><i><span lang="EN-GB">In situ</span></i><span lang="EN-GB"> observations (profiles, time series and trajectories): </span></b><span lang="EN-GB">The existing CF documents describe how station data might be
encoded in CF compliant files in a way which is satisfactory for climate
model output. For in-situ observations, it is potentially rather
inconvenient and inefficient, and alternatives have been proposed, perhaps
using new features of netCDF-4.</span></li>
<li class="MsoNormal" style="text-align:justify"><b><span lang="EN-GB">Discovery
information: </span></b><span lang="EN-GB">While CF describes the data
encoded, it does not include “discovery information”, that is, information
which allows the user to discriminate between two otherwise identical
datasets (for example, two model simulations). There are a large number of
potential discovery content standards, and supporting the information to
populate one or more of them in CF attributes would be desirable.</span></li>
<li class="MsoNormal" style="text-align:justify"><b><span lang="EN-GB">Modularisation
and compliance</span></b><span lang="EN-GB">: It is not yet clear what “CF
compliance” means, even though it is clear that it will mean different
things for datasets and software. Since a great deal of CF is optional,
compliance cannot mean that all features are actually used. It has been
suggested that CF could be broken into modules each of which could be
version controlled, allowing software to claim compliance to specific
components of the CF conventions rather than the whole edifice. Since
archived data cannot easily be changed once written, backward
compatibility for the conventions is a serious issue – should it be an
inviolable principle (as it has been so far)? Development of a CF API and
production of reference datasets may be helpful in promoting good CF
practices and software able to interpret CF metadata.</span></li>
<li class="MsoNormal" style="text-align:justify"><b><span lang="EN-GB">CF
dialects: </span></b><span lang="EN-GB">As the diversity of uses of CF
grows, the need may arise for “varieties” of the standard to be developed
for different applications. Because most of CF is optional, this is not
generally a problem; it simply means that metadata needed in one
discipline will not be used in another. However, a more difficult issue
arises where a structure which suits one variety of data is quite
unsuitable in another, or where a mandatory feature is too onerous (for
instance because it requires too much space for metadata storage). Since
so many needs are in common, it would generally be better for
interoperability and ease of maintenance to develop a single CF standard,
but if it has incompatible dialects, the circumstances in which they
should be used will have to be carefully defined.</span></li>
<li class="MsoNormal" style="text-align:justify"><b><span lang="EN-GB">Automatic
processing:</span></b><span lang="EN-GB"> CF could consider how to support
variable naming from standard names after processing. For example, a
derivative with respect to time of an east-west coordinate should lead to
a standard name which is mapped onto a velocity.</span></li>
<li class="MsoNormal" style="text-align:justify"><b><span lang="EN-GB">External
references: </span></b><span lang="EN-GB">The current CF standard does not
allow for reference to external files that might contain additional useful
metadata, but perhaps it should.</span></li>
</ol>
<p class="MsoNormal"><i><span lang="EN-GB"> </span></i></p>
<h2><span lang="EN-GB">Appendix Two: Terms of Reference for Committees and
Governance Panel</span></h2>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><u><span lang="EN-GB">Constitution of the CF Governance Panel</span></u></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">The CF Governance Panel will come into
existence on </span><span lang="EN-GB">1st October 2006</span><span lang="EN-GB">
and assume its duties and responsibilities from that date. Until that date, the
original CF authors will have responsibility for the governance of the CF
standard.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">The panel will initially be appointed by
the WMO/WCRP Working Group on Coupled Modelling (WGCM) to govern the
development of the CF standard on behalf of the user community. If the WGCM
wishes to transfer or share responsibility for CF with another permanent
committee of an international organisation, it may decide to do so with the
agreement of both CF committees.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">The panel will include, but not be limited
to, members of the WGCM, the leaders, or their nominees, of organisations
contributing significant resources in support of CF, and the chairs of the CF
committees on conventions and standard names.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><u><span lang="EN-GB">Terms of reference of the CF Governance
Panel</span></u></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">The panel will be responsible for the
stewardship of CF, but will not have any special responsibility for or
influence on the technical content of CF.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">The panel will ensure that its own
constitution and terms of reference, those of the CF committees, and the aims
and general principles of design of the CF standard are published. These may be
altered by the panel only after appropriate public debate and with the
agreement of both CF committees.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">The panel will promote and help integrate
the use of CF across WCRP programmes, the broader programmes of WCRP's sponsors
(ICSU, WMO, and IOC), and other interested communities. In particular the panel
will attempt to influence developing metadata standards of WMO and other
international organisations so that they accommodate the CF standard.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">The panel will encourage continued support
of CF by benevolent organisations and explore additional funding mechanisms if
necessary.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">The panel will appoint people who have
nominated themselves or agreed to serve as members of the conventions committee
and the standard names committee. In doing so it will have regard to the
expertise and interests relevant to the remit of each committee and will
attempt to obtain representation of a variety of communities and a geographical
spread of members. The maximum and minimum numbers of members of either
committee may be amended by agreement between that committee and the panel. The
panel will ensure that the current membership of the two CF committees is
published.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><u><span lang="EN-GB">Constitution of the CF committees</span></u></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">Anyone with sufficient time, interest and
expertise is qualified to serve as an ordinary member of the conventions
committee or the standard names committee or both. Prospective ordinary members
will nominate themselves. Before </span><span lang="EN-GB">1st October 2006</span><span lang="EN-GB">, members of the committees will be appointed by the original CF
authors. From </span><span lang="EN-GB">1st October 2006</span><span lang="EN-GB">,
they will be appointed by the CF Governance Panel. Committee members judged by
the panel to have been inactive for an extended period will be asked to resign.
Members may choose to resign at any time and must retire after five years, but
may be reappointed. The maximum number of ordinary members of each committee is
sixteen and the minimum is four.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">The initial chairs of the committees will
be appointed by the original CF authors. Whenever a vacancy arises
subsequently, each committee will elect its own chair from among its ordinary
members. The chair may resign the office at any time and must retire after
three years, but may be reelected.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">Each committee will have authority and
responsibility for the development of the aspects of the CF standard within its
remit, as detailed in its terms of reference, having regard to the aims and
general principles of design of CF. It will discharge its responsibility by
overseeing and contributing to public debate on how the standard should be
expanded or altered, and by deciding after debate whether and what changes will
be made.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">Each committee will be assisted in its
responsibility by a permanent and funded member of staff, who will be appointed
in a manner decided by the CF Governance Panel, and who will be an ex-officio
member and secretary of the committee. The manager of CF conventions will be
the secretary of the conventions committee and the manager of CF standard names
will be the secretary of the standard names committee. The committee will
propose priorities for work by its secretary.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">Each committee will ensure that appropriate
means are made available for making proposals and carrying out debates in a way
which is visible and open to participation by all interested parties, and for
retaining a permanent public record of debates and of any decisions made by the
committee. It will decide the period of time which should be allowed between a
proposal being made publicly and a final decision being required, and any other
procedures necessary. These procedures should assume that community consensus
will generally be followed in deciding for or against changes, but the
committee will make the decision itself if no consensus is evident or the
public debate is inconclusive. The committee may decide exceptionally to make
no change although public consensus is in favour of a change, if it judges that
the proposed change would be damaging to the CF standard. A committee member
who believes this to be case for a particular proposed change should notify the
other members of this opinion before the time arrives by which a decision must
be made according to the rules, and may request the committee to take the
decision itself, rather than allowing public consensus to decide. If such a
request is not made, the secretary will decide what is the outcome of the
public debate and will make or not make changes accordingly.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">A decision by the committee on changes to
the CF standard within its remit or on any procedural matter will require a
simple majority of the membership to be in favour.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">The committees may not devolve
responsibility for the CF standard to other bodies, but they may encourage the
formation of other permanent or temporary ad-hoc groups to debate issues and
propose developments to CF.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">Each committee will ensure that the parts
of the standard for which it is responsible, any supporting documents and
resources, and the procedures for proposing and deciding changes are kept
up-to-date and made publicly available.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">The committees may not change their
constitutions or terms of reference themselves, but each may propose changes to
be made by the CF Governance Panel.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><u><span lang="EN-GB">Terms of reference of the conventions
committee</span></u></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">The conventions committee will be
responsible for the development of the CF conventions constituting the CF
netCDF standard, except for the definition of standard names and of any other
aspects of controlled vocabulary in the appendices to the standard that it
agrees with the standard names committee should be within the remit of that
committee.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">The conventions committee and standard
names committee will together define the format of the standard name table.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">The conventions committee will have an
interest in implementation of CF metadata conventions corresponding to the CF
standard in other file formats and media apart from netCDF.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">The conventions committee will be
responsible for the CF conformance document and for deciding what CF
conformance means.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">The membership of the conventions committee
should include representatives of those who maintain widely used software which
follows the CF conventions, especially those which the committee regards as
reference implementations.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><u><span lang="EN-GB">Terms of reference of the standard names
committee</span></u></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">The standard names committee will be
responsible for the definition of CF standard names and of any other aspects of
controlled vocabulary in the appendices to the CF netCDF standard that it
agrees with the conventions committee should be within its remit.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">The standard names committee will be
responsible for maintaining the standard name table. The standard names
committee and the conventions committee will together define the format of the
standard name table.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">The standard names committee will have an
interest in working towards interoperability with other vocabulary maintainers.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">The standard names committee will make
proposals for modification of conventions when it appears that names cannot be
satisfactorily defined within the prevailing conventions.</span></p>
<p class="MsoNormal"><span lang="EN-GB"> </span></p>
<p class="MsoNormal"><span lang="EN-GB">The membership of the standard names
committee should include representatives of the various scientific user
communities of the CF standard.</span></p>
</div>
<hr>
<div><br clear="all">
<hr align="left" size="1" width="33%">
<div id="ftn1">
<p class="MsoFootnoteText" style="margin-left:.2in;text-indent:-.2in"><a href="#_ftnref1" name="_ftn1" title=""><span class="MsoFootnoteReference"><span lang="EN-GB"><span class="MsoFootnoteReference"><span lang="EN-GB" style="font-size:
10.0pt;font-family:"Times New Roman"">[1]</span></span></span></span></a><span lang="EN-GB"> NCAS/British Atmospheric Data Centre, Rutherford Appleton
Laboratory, U.K. Correspondence to: [email protected]</span></p>
</div>
<div id="ftn2">
<p class="MsoFootnoteText" style="margin-left:.2in;text-indent:-.2in"><a href="#_ftnref2" name="_ftn2" title=""><span class="MsoFootnoteReference"><span lang="EN-GB"><span class="MsoFootnoteReference"><span lang="EN-GB" style="font-size:
10.0pt;font-family:"Times New Roman"">[2]</span></span></span></span></a><span lang="EN-GB"> Program for Climate Model Diagnosis and Intercomparison, </span><span lang="EN-GB">Lawrence</span><span lang="EN-GB"> </span><span lang="EN-GB">Livermore</span><span lang="EN-GB"> National Laboratory, </span><span lang="EN-GB">U.S.A.</span></p>
</div>
<div id="ftn3">
<p class="MsoFootnoteText" style="margin-left:.2in;text-indent:-.2in"><a href="#_ftnref3" name="_ftn3" title=""><span class="MsoFootnoteReference"><span lang="EN-GB"><span class="MsoFootnoteReference"><span lang="EN-GB" style="font-size:
10.0pt;font-family:"Times New Roman"">[3]</span></span></span></span></a><span lang="EN-GB"> </span><span lang="EN-GB">National</span><span lang="EN-GB"> </span><span lang="EN-GB">Center</span><span lang="EN-GB"> for Atmospheric </span><span lang="EN-GB">Research</span><span lang="EN-GB">, </span><span lang="EN-GB">U.S.A.</span></p>
</div>
<div id="ftn4">