1. Task Team for Intercomparison of ReAnalysis
Developed with input from
Michael Bosilovich, NASA GSFC GMAO
Jean-Noël Thépaut, ECMWF
Kazutoshi Onogi, JMA
Arun Kumar, NOAA NCEP
Dick Dee, ECMWF
Otis Brown, NCSU and NOAA

2. TIRA Motivation
Several centers developing reanalyses on a regular basis
Despite wide use in research and applications, average users do not know the subtle differences among them
Uncertainties exist across all reanalyses, information both developers and users need
Intercomparison can be made easier for an “average” user
No international coordinating body exists

3. Grass Roots Intercomparison Projects
Reanalysis.org – Information, shared results, expert oversight
Web-based Reanalysis intercomparison Tool (WRIT) – incorporates recent reanalyses, some visualization, and server-side computations
Stratosphere Reanalysis Intercomparison Project (S-RIP) and Ocean (ORA-IP)– Disciplinary self organized with expert input
Collaborative REAnalysis Technical Environment Intercomparison Project (CREATE-IP) – Placing reanalysis data in the ESGF, similar to CMIP and Obs4MIPS
CORE CLIMAX, 2014: Procedure for comparing reanalyses, and comparing reanalyses to assimilated observations and CDRs. COordinating Earth observation data validation for RE-analysis for CLIMAte Services.

4. Continuing the Momentum
S-RIP shows that the community can take on this problem, but it takes effort, others may benefit from guidance
It would benefit the developing centers to have interactions with the science panels in the intercomparisons/validations
WDAC is the obvious choice for a task team to to fill the void

5. TIRA Objectives Charged to develop an intercomparison Project
To foster understanding and estimation of uncertainties in reanalysis data by intercomparison and other means
To communicate new developments and best practices among the reanalyses producing centers
To enhance the understanding of data and assimilation issues and their impact on uncertainties, leading to improved reanalyses for climate assessment
To communicate the strengths and weaknesses of reanalyses, their fitness for purpose, and best practices in the use of reanalysis datasets by the scientific community

6. Tangible Activities
Communication (support and continuation of reanalysis.org)
Reanalysis Intercomparison Project
Start with a template based on IPCC
CREATE-IP provides technical support, CORE-CLIMAX provides methods
Other WCRP projects should provide support
TIRA guides and provides structure
Joint experimentation/work
Consensus inventory of input observations, updated as new versions become available (incl SSTs, and other disciplinary data for eventual integration)
Add standard output (facilitate inclusion in CREATE-IP)
Contribute to deep understanding with center support

7. Potential Standing Members
Atmospheric Reanalysis Developing Centers
ECMWF, JMA, CMA, NCEP and GMAO
WCRP Panels
GEWEX, CLIVAR, CLiC and SPARC
Others?
Disciplinary – Land/Ocean/Cryo reanalyses
Regional reanalysis projects
Reanalysis user communities? Wind Power