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| ECMWF Reanalysis (ERA5) | |
|---|---|
| Name | ECMWF Reanalysis (ERA5) |
| Started | 2016 |
| Institute | European Centre for Medium-Range Weather Forecasts |
| Area | Global |
| Period | 1950–present (hourly) |
| Variables | Atmospheric, land, ocean-surface |
ECMWF Reanalysis (ERA5)
ERA5 is a global reanalysis dataset produced by the European Centre for Medium-Range Weather Forecasts that provides hourly estimates of a wide range of atmospheric, land and ocean-surface variables from 1950 to the present, supporting studies in climatology, meteorology, hydrology, oceanography, cryosphere research and operational forecasting. It replaces earlier reanalyses by offering higher temporal resolution, finer spatial grid and improved data assimilation compared with predecessors, and it is widely used by institutions such as the World Meteorological Organization, National Aeronautics and Space Administration, National Oceanic and Atmospheric Administration, United Kingdom Met Office and numerous research universities and national meteorological services.
ERA5 provides a consistent reconstruction of the past climate state using a fixed version of the Integrated Forecasting System at ECMWF and a comprehensive assimilation of observations from satellites like NOAA platforms, METOP series, Global Precipitation Measurement (GPM) constellation, TOPEX/Poseidon, Jason missions and radiosonde networks managed by agencies including EUMETSAT, CMA and JMA. The dataset is produced on a regular latitude–longitude grid and on model levels, with variables tailored for users ranging from the Intergovernmental Panel on Climate Change assessments to regional reanalysis downscaling efforts conducted by institutes such as CNRM, KNMI, DWD and Météo-France.
ERA5 includes atmospheric variables (temperature, wind components, vorticity, divergence), thermodynamic fields (specific humidity, relative humidity), surface fluxes (latent heat, sensible heat), radiation components (shortwave, longwave), precipitation types, soil moisture and snow depth, sea surface temperature and sea ice parameters. The dataset also supplies derived products like hourly 10 m wind, 2 m temperature, 2 m dew point, total column ozone and mean sea level pressure, used by stakeholders including European Commission, International Energy Agency, UNESCO, World Bank and researchers at Massachusetts Institute of Technology, ETH Zurich and California Institute of Technology.
ERA5 is generated using four-dimensional variational data assimilation (4D-Var) implemented in ECMWF’s Integrated Forecasting System (IFS) at a specified resolution; the system ingests observations from satellites, radiosondes, aircraft, surface synoptic observations, buoys and profilers. The reanalysis employs bias correction and observation operators adapted to instruments such as Advanced Microwave Sounding Unit (AMSU), Infrared Atmospheric Sounding Interferometer (IASI), Clyde satellite-class sensors and scatterometers used by NASA and ESA missions, and assimilates spaceborne retrievals and direct radiances following protocols endorsed by WMO. Ensemble techniques like the ECMWF Ensemble Prediction System inform uncertainty estimation and probabilistic outputs, and coupling with land-surface models, sea-ice schemes and ocean analyses ensures consistency across domains similar to approaches used by NOAA Climate Prediction Center and UK Met Office Hadley Centre.
Validation of ERA5 involves intercomparison with in situ networks (radiosondes, surface stations), satellite records (e.g., MODIS, AVHRR, CERES), and independent reanalyses including those from NCEP/NCAR, JRA-55 and MERRA-2. Studies by groups at Princeton University, Columbia University and Imperial College London evaluate biases, temporal homogeneity, trend fidelity and representation of extreme events, while operational centers such as ECMWF and NOAA quantify uncertainties via ensemble spread and observation-minus-forecast diagnostics. Limitations include inhomogeneities before the satellite era, representation errors in complex terrain like the Himalaya and Andes, and challenges for tropical cyclones compared with dedicated hurricane analyses used by National Hurricane Center.
ERA5 underpins climate monitoring in reports by IPCC, supports renewable energy assessments for wind and solar projects for companies and agencies like IRENA and European Commission DG Energy, informs hydrological modeling for basin studies in the Amazon Basin, Nile Basin and Mekong River initiatives, aids agricultural analytics for organizations such as FAO and national ministries, and contributes to disaster risk reduction for entities including UNDRR and insurance firms like Swiss Re and Munich Re. It is employed in air quality studies referenced by WHO, in paleoclimate model evaluation at NCAR and in urban climate downscaling for cities like London, New York City, Tokyo and Beijing.
ERA5 data are distributed via the Copernicus Climate Change Service infrastructure and ECMWF’s dissemination systems, accessible through APIs, web portals and cloud platforms used by Amazon Web Services, Google Cloud Platform and Microsoft Azure. Common file formats include NetCDF and GRIB, with data offered on pressure levels, model levels and single-level diagnostics; tools such as Python libraries, xarray, CDO, NCO and GIS platforms like QGIS and ArcGIS facilitate analysis, while workflows integrate with community projects hosted by GitHub and data portals maintained by EMODnet and national centers.
ERA5 succeeded prior ECMWF reanalyses and interrelated efforts such as ERA-Interim and was developed through collaborations among ECMWF, Copernicus, EC and research partners including University of Reading, LSCE and KNMI. Ongoing enhancements lead to higher-resolution experiments and coupled reanalyses combining atmosphere, ocean and chemistry, feeding successor initiatives like ERA6 planning and complementary products such as ERA5-Land. The dataset continues to evolve with advances in data assimilation, increased satellite missions (e.g., Sentinel series), and integration with community models at centers like NOAA Geophysical Fluid Dynamics Laboratory and Max Planck Institute for Meteorology.
Category:Reanalysis datasets