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ERA-Interim Project

| DOI: 10.5065/D6CR5RD9

This historical dataset is recommended for ancillary use only and not as a primary research dataset. It has likely been superseded by a newer, improved dataset.


ERA-Interim represents a major undertaking by ECMWF (European Centre for Medium-Range Weather Forecasts) to produce a reanalysis with an improved atmospheric model and assimilation system which replaces those used in ERA-40, particularly for the data-rich 1990s and 2000s, and to be continued as an ECMWF Climate Data Assimilation System (ECDAS) until superseded by a new extended reanalysis. Preliminary runs indicated that several of the inaccuracies exhibited by ERA-40 such as too-strong precipitation over oceans from the early 1990s onwards and a too-strong Brewer-Dobson circulation in the stratosphere, were eliminated or significantly reduced. Production of ERA-Interim, from 1989 onwards, began in summer of 2006. (The period 1979-1988 was prepended in 2011.)

Through systematic increases of computing power, 4-dimensional variational assimilation (4D-Var) became feasible and part of ECMWF operations since 1997, paving the way to base ERA-Interim on 4D-Var (rather than 3D-Var as in ERA-40). Enhanced computing power also allowed horizontal resolution to be increased from T159 (N80, nominally 1.125 degrees for ERA-40) to T255 (N128, nominally 0.703125 degrees), and the latest cycle of the atmospheric model (IFS CY31r1 and CY31r2) to be used, taking advantage of improved model physics. ERA-interim retains the same 60 model levels used for ERA-40 with the highest level being 0.1 hectopascal. In addition, data assimilation of ERA-Interim also benefits from quality control that draws on experience from ERA-40 and JRA-25, variational bias correction of satellite radiance data, and more extensive use of radiances with an improved fast radiative transfer model.

ERA-Interim uses sets of observations and boundary forcing fields acquired for ERA-40 through 2001, and from ECMWF operations thereafter. Noteworthy exceptions include new ERS (European Remote Sensing Satellite) altimeter wave heights, EUMETSAT (European Organisation for the Exploitation of Meteorological Satellites) reprocessed winds and clear-sky radiances, GOME (Global Ozone Monitoring Experiment) ozone data from the Rutherford Appleton Laboratory, and CHAMP (CHAllenging Minisatellite Payload), GRACE (Gravity Recovery and Climate Experiment), and COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate) GPS radio occultation measurements processed and archived by UCAR (University Corporation for Atmospheric Research).

NCAR's Data Support Section (DSS) is performing and supplying a grid transformed version of ERA-Interim, in which variables originally represented as spectral coefficients or archived on a reduced Gaussian grid are transformed to a regular 512 longitude by 256 latitude N128 Gaussian grid. In addition, DSS is also computing horizontal winds (u-component, v-component) from spectral vorticity and divergence where these are available. Processing of analysis groups and the surface forecast has been completed for January 1979 through December 2014 (inclusive), or at least 36 years, and will continue as ERA-Interim becomes available thereafter. Data is currently available via NCAR's High Performance Storage System (HPSS), or by delayed mode request which transfers files from the HPSS to our web server for internet download, or via direct internet download, or NCAR's GLADE file system.

Temporal Range:
1979-01-01 00:00 +0000 to 2019-09-10 12:00 +0000 (Entire dataset) Period details by dataset product
Usage Restrictions:

Downloading/Accessing data from this dataset implies acceptance of ECMWF's Terms of Use

Air Temperature Albedo Albedo Cloud Frequency
Cloud Liquid Water/Ice Convection Convergence Dew Point Temperature
Evaporation Geopotential Height Gravity Wave Heat Flux
Humidity Hydrostatic Pressure Ice Extent Incoming Solar Radiation
Longwave Radiation Maximum/Minimum Temperature Outgoing Longwave Radiation Planetary Boundary Layer Height
Potential Temperature Precipitation Amount Runoff Sea Level Pressure
Sea Surface Temperature Shortwave Radiation Skin Temperature Snow
Snow Density Snow Depth Snow/Ice Temperature Snow/Ice Temperature
Snow Melt Soil Moisture/Water Content Soil Temperature Streamfunctions
Sunshine Surface Pressure Surface Roughness Surface Winds
Terrain Elevation Total Precipitable Water Tropospheric Ozone Upper Air Temperature
Upper Level Winds Vegetation Cover Vegetation Species Vertical Wind Velocity/Speed
Vorticity Water Vapor Wind Stress
GRIB parameter table: HTML | XML
Vertical Levels:
See the detailed metadata for level information.
Data Types:
Spatial Coverage:
Longitude Range: Westernmost=180W Easternmost=180E
Latitude Range: Southernmost=89.463S Northernmost=89.463N Detailed coverage information
Data Contributors:
European Centre for Medium-Range Weather Forecasts
Palmeiro, F. M., D. Barriopedro, R. García-Herrera, and N. Calvo, 2015: Comparing Sudden Stratospheric Warming Definitions in Reanalysis Data J. Climate, 28, 6823-6840 (DOI: 10.1029/2009JD012442).

Berg, L. K., L. D. Riihimaki, Yun Qian, H. Yan, and M. Huang, 2015: The Low-Level Jet over the Southern Great Plains Determined from Observations and Reanalyses and Its Impact on Moisture Transport J. Climate, 28, 6682-6706 (DOI: 10.1029/2009JD012442).

Chen, G., T. Iwasaki, H. Qin, and W. Sha, 2014: Evaluation of the Warm-Season Diurnal Variability over East Asia in Recent Reanalyses JRA-55, ERA-Interim, NCEP CFSR, and NASA MERRA J. Climate, 27(14), 5517-5537 (DOI: 10.1029/2009JD012442).

Lindsay, R., M. Wensnahan, A. Schweiger, and J. Zhang, 2014: Evaluation of Seven Different Atmospheric Reanalysis Products in the Arctic J. Climate, 27(7), 2588-2606 (DOI: 10.1029/2009JD012442).

Dee, D. P., M. Balmaseda, G. Balsamo, R. Engelen, A. J. Simmons, and J.-N. Thepaut, 2014: Toward a Consistent Reanalysis of the Climate System Bull. Amer. Meteor. Soc., 95(8), 1235-1248 (DOI: 10.1029/2009JD012442).

Zappa, G., L. Shaffrey, and K. Hodges, 2014: Can Polar Lows be Objectively Identified and Tracked in the ECMWF Operational Analysis and the ERA-Interim Reanalysis?. Mon. Wea. Rev., 142(8), 2596-2608 (DOI: 10.1029/2009JD012442).

Siam, M. S., M.-E. Demory, and E. A. B. Eltahir, 2013: Hydrological Cycles over the Congo and Upper Blue Nile Basins: Evaluation of General Circulation Model Simulations and Reanalysis Products J. Climate, 26(22), 8881-8894 (DOI: 10.1029/2009JD012442).

Decker, Mark, Michael A. Brunke, Zhuo Wang, Koichi Sakaguchi, Xubin Zeng, Michael G. Bosilovich, 2012: Evaluation of the Reanalysis Products from GSFC, NCEP, and ECMWF Using Flux Tower Observations J. Climate, 25, 1916-1944 (DOI: 10.1029/2009JD012442).

Berrisford, P., P. Kallberg, S. Kobayashi, D. Dee, S. Uppala, A. J. Simmons, P. Poli, and H. Sato, 2011: Atmospheric conservation properties in ERA-Interim Quart. J. R. Meteorol. Soc., 137, 1381-1399 (DOI: 10.1029/2009JD012442).

Trenberth, Kevin E., John T. Fasullo, Jessica Mackaro, 2011: Atmospheric Moisture Transports from Ocean to Land and Global Energy Flows in Reanalyses J. Climate, 24, 4907-4924 (DOI: 10.1029/2009JD012442).

Dee, D. P., with 35 co-authors, 2011: The ERA-Interim reanalysis: configuration and performance of the data assimilation system Quart. J. R. Meteorol. Soc., 137, 553-597 (DOI: 10.1029/2009JD012442).

Simmons, A. J., K. M. Willett, P. D. Jones, P. W. Thorne, and D. P. Dee, 2010: Low-frequency variations in surface atmospheric humidity, temperature and precipitation: Inferences from reanalyses and monthly gridded observational datasets J. Geophys. Res., 115, 1-21 (DOI: 10.1029/2009JD012442).

Poli, P., S. B. Healy, and D. P. Dee, 2010: Assimilation of Global Positioning System Radio Occultation data in the ECMWF ERA-Interim reanalysis Quart. J. R. Meteorol. Soc., 136, 1972-1990 (DOI: 10.1029/2009JD012442).

Kobayashi, S., M. Matricardi, D. P. Dee, and S. Uppala, 2009: Toward a consistent reanalysis of the upper stratosphere based on radiance measurements from SSU and AMSU-A Quart. J. R. Meteorol. Soc., 135, 2086-2099 (DOI: 10.1029/2009JD012442).

Dee, D. P., and S. Uppala, 2009: Variational bias correction of satellite radiance data in the ERA-Interim reanalysis Quart. J. R. Meteorol. Soc., 135, 1830-1841 (DOI: 10.1029/2009JD012442).

Simmons, A, S. Uppala, D. Dee, and S. Kobayashi, 2007: ERA-Interim: New ECMWF reanalysis products from 1989 onwards. Newsletter 110 - Winter 2006/07, ECMWF, 11 pp. (DOI: 10.1029/2009JD012442)

Total Volume:
38.69 TB (Entire dataset) Volume details by dataset product
Data Formats:
Related RDA Datasets:
ERA40 T106 6-hourly Surface Analysis and Surface Forecast Fields, created at NCAR
ERA40 T106 Analysis Fields on Pressure Surfaces, created at NCAR
ERA40 T106 Analysis Fields on Model Levels, created at NCAR
Japanese 25-year Reanalysis Project
Japanese 25-year Reanalysis Project, Monthly Means
ERA-20C Project (ECMWF Atmospheric Reanalysis of the 20th Century)
ERA-Interim Project, Monthly Means
ERA-Interim Project, Single Parameter 6-Hourly Surface Analysis and Surface Forecast Time Series
JRA-55: Japanese 55-year Reanalysis, Daily 3-Hourly and 6-Hourly Data
JRA-55: Japanese 55-year Reanalysis, Monthly Means and Variances
WCRP and WWRP THORPEX YOTC (Year of Tropical Convection) Project, Single Parameter 6-Hourly Surface Analysis and Surface Forecast Time Series, Transformed to a Regular 1600 by 800 (N400) Gaussian Grid
WCRP and WWRP THORPEX YOTC (Year of Tropical Convection) Project, Single Parameter 6-Hourly Pressure Level Analysis Time Series, Transformed to a Regular 1600 by 800 (N400) Gaussian Grid
WCRP and WWRP THORPEX YOTC (Year of Tropical Convection) Project, Single Parameter 6-Hourly Pressure Level Forecast Time Series, Transformed to a Regular 1600 by 800 (N400) Gaussian Grid
WCRP and WWRP THORPEX YOTC (Year of Tropical Convection) Project, Single Parameter 6-Hourly Model Level Analysis Time Series, Transformed to a Regular 1600 by 800 (N400) Gaussian Grid
WCRP and WWRP THORPEX YOTC (Year of Tropical Convection) Project, Single Parameter 3-Hourly Surface Forecast Time Series, Transformed to a Regular 1600 by 800 (N400) Gaussian Grid
ERA5 Reanalysis
More Details:
View a more detailed summary of the data, including specific date ranges and locations by parameter
Metadata Record:
Data License:
Citation counts are compiled through information provided by publicly-accessible APIs according to the guidelines developed through the project. If journals do not provide citation information to these publicly-accessible services, then this citation information will not be included in RDA citation counts. Additionally citations that include dataset DOIs are the only types included in these counts, so legacy citations without DOIs, references found in publication acknowledgements, or references to a related publication that describes a dataset will not be included in these counts.