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

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

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.

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

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

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

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