Eos, Vol. 94, No. 13, 26 March 2013

VOLUME 94

NUMBER 13

26 MARCH 2013
EOS, TRANSACTIONS, AMERICAN GEOPHYSICAL UNIONPAGES 121–132

Climate Data Guide Spurs
Discovery and Understanding

satellite platform, utility for model diagnostics,
or designation in a special category such as
Climate Data Record [e.g., National ResearchCouncil, 2004].
To illustrate the utility of the expert-user
guidance entries, consider the case of cloud
fraction data from the International Satellite
Cloud Climatology Project (ISCCP) [Pincusand National Center for Atmospheric Research
Staff, 2013, and references therein]. Cloud
fraction information is invaluable to climate
scientists studying Earth’s radiation budget,
as well as to renewable energy developers
interested in a region’s solar energy potentialand many others. As summarized under“Key Strengths” on the guide’s ISCCP Web
page, ISCCP is a high-value data set due toits 3- decade length and global, sub- daily
sampling.
One issue, however, is that the comparisonof cloud amounts across regions can be anapples-to- oranges problem because theinconsistent viewing angle and changing
instrumentation of geostationary satellites
create artifacts in ISCCP’s spatial patterns.
Further, as cloud changes are one of the main
uncertainties in climate change projections,assessing the performance of climate models
with data sets such as ISCCP is important ingaining confidence in the projections.
However, even if analysts apply cloud
simulators to the model output, ISCCP datapose special challenges due in part to thetreatment of partly cloudy pixels, as highlighted in another expert-user guidance entry[Kay and National Center for AtmosphericResearch Staff, 2013].
While issues like these are often wellknown among a small circle of researchers,
it has been difficult to communicate themto the expanding community of users. The
guide thus plays a key role in disseminatingvital end user information. Before posting
reviews, metadata, and links, the guideverifies their general accuracy and validity.
However, users are encouraged to postcomments and questions about the reviews
and to report broken links and/or errors in
the metadata. Users seeking more in-depth
analyses and further details can follow
links from the guide to supporting peerreviewed literature or to data set– specificWeb sites.
As the guide places emphasis on community input and focuses on a limited selectionof data sets that are most useful for largescale climate research and model evaluation,

PAGES 121–122
Highly accurate and stable observations—beyond those provided by routine weather
monitoring—are essential for understanding
the behavior of the climate system, developing and validating Earth system models,and attributing extreme weather eventsand long-term trends to causes [NationalResearch Council, 2012; Trenberth et al.,2013]. In parallel with an exploding volumeof climate data, ready access to data inuser-friendly formats is important to anexpanding number and increasing diversityof individuals worldwide across public,private, and academic sectors [Overpecket al., 2011].
Not only are these users challenged to deal
with enormous data volumes, but they also
must choose from the multitude of data setsthat are available for many variables, fromstratospheric ozone to soil moisture [NationalResearch Council, 2012]. Faced with suchdecisions, some users may select data setsbased upon convenience of access orfamiliarity of format rather than suitability foraddressing the question at hand. Many
researchers and professionals work with datafrom outside their core field of training andlack the knowledge, time, and motivation tothoroughly survey and synthesize theliterature and documentation on unfamiliar
data sets. In addition to these challenges,
along with increased data accessibility comesa responsibility for users to appreciate thenuances and biases of individual data sets
and for data experts to communicate these
openly.
How can the hard-earned knowledge
about the strengths and limitations ofindividual data sets best be shared with thecommunity? Funded by the National Science
Foundation’s Earth System Modeling (EaSM)
initiative, the Climate Data Guide (http://climatedataguide.ucar.edu) is being developed as a community-authored guide to the

BY D. P. SCHNEIDER, C. DESER, J. FASULLO,AND K. E. TRENBERTH

world of climate data sets. The Web site
provides concise and reliable information
on data strengths and limitations, enablingusers to make more informed selections ofdata sets for their own research and to better
understand the data and analysis methods
that are encountered in numerous contexts(e.g., in publications, proposals, presentations, classes, Web sites).

Goals, Specifics, and a Case Study of theClimate Data Guide
The unique function of the Climate Data
Guide (hereafter “the guide”) is the gatheringand dissemination of well-informed perspectives on the essential features, strengths,limitations, and utility of a broad range ofdata sets. The guide actively solicits commentary from both data set developers andexperienced users. These perspectives,
referred to as “expert-user guidance,” addressquestions such as, “What are the typicalresearch applications of this data set? Whatare the most common mistakes that users
encounter when processing or interpretingthese data? What are some comparable data
sets, if any? How is uncertainty characterized
in these data? How do I best compare thesedata with model output? Are there spurious(nonclimatic) features in the temporal
record?”Based at the National Center for
Atmospheric Research (NCAR), the guide’s
Web site profiles more than 100 observational
climate data sets including atmosphericreanalyses, satellite data, and climate indices.
Each profile contains descriptions of a data
set’s key strengths, limitations, and typicaluses, tailored to Earth system modelevaluation and general climate research.
Metadata (period of record, spatial coverage,formatting, etc.) are provided along with links
to download servers, relevant peer-reviewed
publications, and product Web sites. To
facilitate comparisons, this database- driven
Web site generates dynamic lists and tablesof data sets organized by different attributes,
such as by variable, Earth system component(atmosphere, cryosphere, ocean, etc.),© 2013. American Geophysical Union. All Rights Reserved.

Eos, Vol. 94, No. 13, 26 March 2013
it serves a different purpose from typical datarepositories or directories, for example, theNational Climatic Data Center (http://www.
ncdc.noaa.gov) or the Global Change Master
Directory (http://gcmd.nasa.gov). Moreover,data set profiles in the guide are presented ina consistent, accessible style and are notlimited to the products of a single agency orfunding call. The guide incorporates thebroad range of data sets in common usage
among climate researchers.

Highlights of the Guide’s First OperationalYear2012 was the first full calendar year ofoperation for the guide. Usage was tracked
with a commonly used log analyzer (AWStats;
http://awstats.sourceforge.net) as well as
Google Analytics (http://www.google.com/analytics). Additional information on user
demographics and interests was gathered
through an optional registration process(https://climatedataguide.ucar.edu/user/register) that enables users to post comments
and upload materials to be featured on theWeb site. In 2012 there were in excess of
40,000 unique visitors, more than 300,000
page views, and nearly 2.3 million hits.
Visitors came from more than 100 countries,
with 36% of traffic from the United States.
The United Kingdom, China, Germany, andCanada rounded out the top five countries
contributing Web traffic. Nearly half ofvisitors came via search traffic, while 30%
came through referrals from establishedprograms within NCAR as well as fromexternal programs with which the guide has
made efforts to interface, for example, theCoupled Model Intercomparison Project(http://cmip -pcmdi.llnl.gov).
The guide attracted nearly 600 registeredusers in 2012. Their range of occupations
and nationalities supports assertions of an
expanding and diversifying market for climate
data and knowledge [e.g., Overpeck et al.,2011]. The list of registered users includesgraduate students and professors, scientists
and engineers in the public and private
sectors, and analysts in fields such as
insurance and renewable energy. Basedon usage trends so far, the user base is
expected to grow significantly in 2013, witha projected 50–100% growth in site visits
over 2012.

Community Involvement in Improving
the Guidelist of expert contributors (https://climatedataguide.ucar.edu/experts-list).

The guide is a cost- effective solution tocalls by both scientists [e.g. Overpeck et al.,2011] and funding agencies [National ScienceFoundation, 2013] to share climate data andresearch methods transparently, freely,and effectively. Each contributor of expertuser guidance is acknowledged, andindividual pages and reviews are citable.
Text, figures, publication lists, and metadata
may be uploaded to the Web site or e-mailed
to climatedataguide@cgd.ucar.edu.
Registered users are alerted to new content
via e-mail notifications, although anyone may
follow updates through Really Simple
Syndication (RSS) feeds and, in the future,through social media. In addition, to better
serve its diverse and growing audience,
project leaders plan to update the guide by
improving its Web design, search tools, anduser interfaces; reaching out across social
media and mobile platforms; and, mostimportant, incorporating broad input fromthe climate research community.
Currently, the most comprehensive
coverage on the guide is for atmospheric andsurface climate variables, including thoseused to diagnose the performance of theCommunity Atmosphere Model, a componentof NCAR’s Community Earth System Model(CESM). Most major model diagnostic data
sets used by CESM and other Earth systemmodels will be incorporated into the guide
over the next year. Other categories to be
expanded are boundary condition andforcing data sets used in historical climate
simulations, satellite data sets, and reprocessed data sets of broad interest, such as
those considered in the Climate Data Records
and the Global Energy and Water Cycle
Experiment projects [see Trenberth et al., 2013;
http://www.gewex.org].
Through these efforts, data sets andpublications profiled on the guide will
become more accessible and visible.
However, the success of this endeavor hinges
upon community participation.
Strong participation in this vital community
resource will help to ensure that researchers
are well equipped to address the complex
questions that pertain to past, present, andfuture climate. The Climate Data Guide invites
scientists to add themselves to the growing

Acknowledgments© 2013. American Geophysical Union. All Rights Reserved.

We gratefully acknowledge the National
Science Foundation’s support for the Climate
Data Guide (grant 1048899). A. Phillips,A. Dai, J. Hurrell, and D. Shea have been
instrumental to the project, and theircomments helped to improve this paper. We
thank two anonymous reviewers for theirhelpful comments.

References
Kay, J., and National Center for AtmosphericResearch Staff (Eds.) (2013), The Climate Data
Guide: COSP: Cloud Feedback Model Intercomparison Project (CFMIP) Observation Simulator
Package, Natl. Cent. for Atmos. Res., Boulder,Colo. [Last modified 8 January 2013. Available
at http://climatedataguide.ucar.edu/guidance/cosp‐cloud‐feedback‐model‐intercomparison‐project‐cfmip‐observation‐simulator‐package.]
National Research Council (2004), Climate Data
Records from Environmental Satellites, 150 pp.,Natl. Acad. Press, Washington, D. C.
National Research Council (2012), A National
Strategy for Advancing Climate Modeling, 280 pp.,Natl. Acad. Press, Washington, D. C.
National Science Foundation (2013), Dissemination and sharing of research results, in Award
and Administration Guide, chap. VI.D.4,
Washington, D. C. [Available at http://www.nsf.
gov/pubs/policydocs/pappguide/nsf13001/aag_6.
jsp#VID4.]
Overpeck, J. T., G. A. Meehl, S. Bony, and D. R.
Easterling (2011), Climate data challenges in the
21st century, Science, 331, 700 –702, doi:10.1126/
science.1197869.
Pincus, R., and National Center for AtmosphericResearch Staff (Eds.) (2013), The Climate Data
Guide: ISCCP: International Satellite Cloud Climatology Project, Natl. Cent. for Atmos. Res.,
Boulder, Colo. [Last modified 4 January 2013.
Available at http://climatedataguide.ucar.edu/guidance/isccp‐international‐satellite‐cloud‐climatology‐project.]Trenberth, K. E., et al. (2013), Challenges of asustained climate observing system, in Climate
Science for Serving Society: Research, Modelingand Prediction Priorities, edited by J. W. Hurrell
and G. Asrar, Springer, Berlin, in press.
—DAVID P. SCHNEIDER, CLARA DESER,JOHN FASULLO, and KEVIN E. TRENBERTH, National
Center for Atmospheric Research, Boulder, Colo.;E-mail: climatedataguide@cgd.ucar.edu

Eos, Vol. 94, No. 13, 26 March 2013

© 2013. American Geophysical Union. All Rights Reserved.