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Created by esrl_admin on - Updated on 12/03/2023 21:33


Reanalysis is a scientific method for developing a comprehensive record of how weather and climate are changing over time. In it, observations and a numerical model that simulates one or more aspects of the Earth system are combined objectively to generate a synthesized estimate of the state of the system. A reanalysis typically extends over several decades or longer, and covers the entire globe from the Earth’s surface to well above the stratosphere. Reanalysis products are used extensively in climate research and services, including for monitoring and comparing current climate conditions with those of the past, identifying the causes of climate variations and change, and preparing climate predictions. Information derived from reanalyses is also being used increasingly in commercial and business applications in sectors such as energy, agriculture, water resources, and insurance.


Using a collaborative Wiki framework, the goal of is to facilitate comparison between reanalysis and observational datasets. Evaluative content provided by reanalysis developers, observationalists, and users; and links to detailed data descriptions, data access methods, analysis and plotting tools, and dataset references are available. Discussions of the recovery of observations to improve reanalyses is also a focus. The wiki framework encourages scientific discussion between members of and other reanalysis users.

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       New!  A new Japanese global atmospheric reanalysis JRA-3Q is available.

       Reanalysis Session at 2022 AGU

       Workshop on Future US Earth System Reanalysis - US CLIVAR

What is Reanalysis: Resources (Background, animations, overview)

Copernicus Video on Reanalysis

How to obtain ocean data and plots: Updated. 

Met Office Hadley Centre Integrated Ocean Database (HadIOD) 1850-present: A database of ocean temperature and salinity observations NEW!

MERRA-2 Weather Maps www page

Recently published: Introduction to the SPARC Reanalysis Intercomparison Project (S-RIP) and overview of the reanalysis systems 


JRA-55: Some tropical cyclones occurring over the Northeast Pacific and the North Atlantic from 1959 to 1987 were erroneously represented as anti-cyclonic vortices in the Japanese 55-year Reanalysis (JRA-55) dataset.

LMRv2: NOAA has released v2 of the Last Millennium Reanalysis project at annual resolution. More details here.

ERA5: ECMWF has released their full-input atmospheric reanalysis spanning 1959 to present at hourly resolution. More details here.

20CRv3: NOAA, CIRES, and DOE have just released an improved version of the 20th Century Reanalysis, "3", spanning 1806-2015. More details here.

CERA-20C: ECMWF has released their second reanalysis (and first coupled) of the 20th century. More details here.

MERRA-2: NASA GMAO has released a new version of the MERRA dataset spanning 1980 to present. More details here.


Pages and Meetings

Area for Questions, Notes, and Comments on recently released Atmospheric Reanalyses: Ask a Question