GCOS/WCRP Working Group on Observational Data Sets For Reanalysis

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GCOS/WCRPWorking Group onObservational Data
SetsFor Reanalysis

• Vose et al.

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4 Terms of Reference

• Review data center holdings worldwide
• Develop a plan for integrated data sets
• Oversee progress of Implementing Centers
• Report regularly to AOPC and WOAP

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Generalities

• The Working Group has
• Assembled surface and upper air data set
  inventories
• Augmented existing data sets
• Developed plans for improving specific data sets
• Focused on upcoming reanalyses
• Served as a catalyst (e.g., NCDC wouldnt have
  done)
• The Working Group has not
• Denoted official Implementing Centers (loose
  confederation has generated products thus far)
• Held many meetings (one in Tokyo e-mail and
  phone calls otherwise Trenberth encourages
  proposal for another)

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Dataset Activities

• 20th Century Reanalysis (C20R)
• International Surface Pressure Databank (ISPD)
• International Comprehensive Ocean Atmosphere
  Dataset
• International Best Track Archive for Climate
  Stewardship
• Other data set activities (for ECMWF, etc.)
• C20R datasets listed above
• Integrated Global Radiosonde Archive (IGRA)
• Satellite products (Bates, Zou, etc. encourage me
  to credit these activities to the working group,
  but thats a stretch still, the data sets do
  benefit reanalyses)

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C20R Support
0500 UTC Jan. 22, 1918 (ISPD)
0000 UTC Jan. 22, 1918 (C20R)
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Surface Pressure ISPD 2.2.4

• GCOS/AOPC/OOPC Surface Pressure Working Group
• Identify, retrieve, digitize, merge, QC
• Some numbers
• 33 data sources
• 33,653 stations
• 1.7 billion obs
• 1768-2008
• V3 in late 2010

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Marine Data ICOADS 2.5

• Surface reports from ships, buoys, other
  platforms
• SST, pressure, humidity, etc.
• 1662-2007, with preliminary updates thereafter
• Many new historical sources digitized

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Tropical Cyclones IBTrACS 2.0

• 1st central repository, worlds largest archive
• 14 source datasets (including all RSMCs)
• 10,000 storms from 1840-present

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Other Dataset Activities

• Integrated Global Radiosonde Archive (IGRA)
• Satellite products
• SSM/I and SSMIS (NCDC, CSU, NESDIS/STAR)
• MSU/AMSU (NESDIS/STAR et al.)

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Upper Air Data
Integrated Global Radiosonde Archive (IGRA)

• Variables
• pressure
• geopotential height
• temperature
• dew point depression
• wind direction/speed

• Notables
• v1 done in 2005
• v2 underway
• 42 source datasets (vs. 11)
• All reformatted
• Merging in process (no eta)

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IGRA v1
IGRA v2
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SSM/I and SSMIS

• Extended/improved period of record (1987-present)
• Completed in 2010, freely available from NCDC
• Fundamental climate data record effort by CSU and
  NESDIS/STAR is ongoing
• High-quality but proprietary RSS product still
  available for purchase

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NESDIS/STAR MSU/AMSU

• V2 SNO out
• 1979-2009
• TIROS-N to NOAA-18, MetOp-A
• V1 used in CFSR, MERRA

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Reviewing theTerms of Reference-- Slides with
? more feedback, please --
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Need Feedback On

• CCl partnership
• More data set development work
• Radiosonde temperature metadata
• Better BUFR capability
• Web-based catalogue
• Working Group meeting
• Other suggestions

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Term of Reference 1

• Review
• The holdings of data centres worldwide for
  observations suitable for use in reanalysis or in
  observational studies.
• The opportunities for enhancement of these
  holdings through data recovery, collection, and
  reprocessing.
• Thoughts
• Well intentioned but works better when driven by
  a specific need (e.g., C20R).
• Somewhat related to Met Office proposal to CCl on
  International Analysis of Land Surface Air
  Temperature (hold comments until next slide)

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Partnership with CCl?

• Participation in workshop on Creating Surface
  Temperature Datasets to Meet 21st Century
  Challenges (preferably with a broader mandate)
• Real-time monitoring of synoptic reports by the
  working group (information passed to CCl, which
  in turn can encourage more reporting by
  individual countries helps future reanalyses)

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Continue Other Review Efforts?

• Focus on upcoming surface-only reanalyses by
  ECMWF and NOAA
• Implies surface pressure (ISPD) and other primary
  surface elements (Integrated Surface Dataset)
• Maybe a little more on the radiosonde record
  (ERA-CLIM)
• Implies more work on IGRA

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Term of Reference 2

• Develop a plan for data sets
• Merging of holdings incorporating metadata
• Development of standards, version control,
  software
• Identification of an Implementing Centre for
  data sets
• Extension of data sets in close to real time
• Maintenance and publication of a catalogue of
  data sets
• Thoughts
• We have developed data sets instead. This will
  continue.
• Some radiosonde temperature metadata work is
  needed.
• More work on standards is possible, but its
  tough.
• The time has come for the data set catalogue.

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Sonde Temperature Metadata?

• When there were breaks, how big they were, how
  certain
• Include both documented and inferred changes
• Also include observation minus background (MERRA,
  C20R)
• Basically give the assimilation system more
  information
• Or even try to homogenize (recommendation from
  SDS workshop, Microwave group)

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Better BUFR Capability?

• Universal formats are useful
• As are nice interfaces to those formats
• Can manage both input data and feedback
• Tedious to develop
• Diverging opinions within the working group on
  this

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Web-Based Catalogue?

• A compilation, updated regularly, would be a
  major service.
• What there is, where it is, how to get it
• WG members can volunteer what they know, provide
  contacts
• Keep our pulse on the latest and greatest for
  each data set
• Hosted at NCDC
• Alternative to the Implementing Centre

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Small, Focused Workshop

• Working group members and selected others
• Add-on to another meeting
• 3rd ACRE workshop Reanalysis and Applications
  and the U.S. Reanalysis/IESA workshop in
  Baltimore, MD (Nov. 2010)
• But those two meetings take up 5 days already
• Funding may be available through WOAP
• Key issues are how our activities relate to and
  take advantage of current reanalyses
• Again, feedback welcome

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• Reanalyses Suitable for Characterizing Long-Term
  Trends Are They Really Achievable?
• P.W. Thorne and R.S. Vose
• Reanalyses are, by a substantial margin, the
  most utilized climate data products, and they are
  applied in a myriad of different contexts.
  Despite their popularity, there are substantial
  concerns about their suitability for the
  monitoring of long-term climate trends. This has
  led to calls for a truly climate quality
  reanalysis that retains long-term trend fidelity.
  The authors contend that for such a reanalysis to
  be achieved, a substantial rethinking of the
  current strategy for producing reanalysis
  products is required. First, the problem must be
  defined clearly. Second, the methodology that is
  employed must be reconsidered so as to minimize
  potential nonclimatic artifacts and robustly
  ascertain the inevitable residual uncertainty.
  Finally, a set of validation data and metrics
  must be constructed that the community can use to
  compare and unambiguously assess the claims of
  climate quality. The purpose of this essay is
  very much to initiate discussions to this end
  rather than to prescribe solutions.
• (To be published in BAMS, March 2010)