Climate Reanalysis Research

Reanalysis integrates the instrumental record with model forecasts, produces a coherent set of climate variables for monitoring and analysis of climate variability, and supports climate prediction and climate model development. Reanalysis datasets have been identified as an important component of the WMO Global Framework for Climate Services. Major reanalysis datasets have recently been developed in the US (CFSR, MERRA, 20CR) and internationally (e.g., ERA-Interim, JRA-25). Evaluation of these datasets has demonstrated many advances (e.g., improvements in the representation of intraseasonal variability, and the capability to represent climate anomalies back to the early 1900s) but has also highlighted issues that limit the use of these datasets for climate studies. These include spurious trends and jumps associated with the changing observing system, shortcomings in the representation of the hydrological cycle and surface fluxes, and issues with the quality of reanalyses in the stratosphere and in polar regions. (For a technical report on this topic, see Newly available remotely-sensed data, the development of Earth System models, and the benefits that would derive from more consistent states across analysis components, all point to a considerable interest in integrated Earth System reanalysis systems, including some level of coupling among the various analysis components (e.g., atmosphere and ocean).

MAPP Program has the broad objective to advance NOAA’s climate reanalysis capability. Activities include:

  • Past MAPP investments to develop Climate Forecast System Reanalysis (CFS-R) and 20th Century Reanalysis. ( (Supported FY08-FY12)
  • Planned investments for FY13-FY15 include research to 1) Address outstanding issues in atmospheric reanalysis to improve upon past NOAA re-analysis products 2) Explore the integration among Earth System reanalysis components. Research will be carried out as part of the Climate Reanalysis Task Force.
  • The CRTF organized a technical workshop on May 4-5, 2015 for the purpose to highlight advancements across NOAA, university and international efforts, identify gaps, and improve coordination of future activities to meet the requirements of the diverse array of users of reanalyses. View the workshop page for more information.
  • Connecting with, a tool used by the CRTF to advance climate reanalysis, providing coordination in part of a global effort to advance reanalysis.



Climate Program Office
1315 East-West Hwy, Suite 1100
Silver Spring, MD 20910


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