ERA-Interim Project

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for the data-rich 1990s and 2000s, and to be continued as an ECMWF Climate Data Assimilation System (ECDAS) until superseded by a new extended reanalysis.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.

To Access Resource:

Questions? Email Resource Support Contact:

  • Dave Stepaniak
    davestep@ucar.edu
    UCAR/NCAR - Research Data Archive

Temporal Range

  • Begin:  1979-01-01T00:00:00Z
    End:  2019-07-10T18:00:00Z

Keywords

Resource Type dataset
Temporal Range Begin 1979-01-01T00:00:00Z
Temporal Range End 2019-07-10T18:00:00Z
Temporal Resolution N/A
Bounding Box North Lat 89.463
Bounding Box South Lat -89.463
Bounding Box West Long -180
Bounding Box East Long 180
Spatial Representation grid
Spatial Resolution 0.703 degree
Related Links

Related Resource #1 : ECMWF Downloadable Datasets

Related Resource #2 : Description of ERA-Interim at the NCAR Climate Data Guide

Additional Information N/A
Asset Size 38528447 MB
Legal Constraints

Please see: Terms of Use for ECMWF Data (Other Than Operational Data) [https://rda.ucar.edu/datasets/ds627.0/docs/terms_of_use.html]


Access Constraints Must be a registered user of RDA ECMWF Data (Other Than Operational Data). Please update your current RDA user profile by clicking on the "ECMWF Data (Other Than Operational Data)" terms of acceptance, or create a new RDA user profile if you have not already done so (and click on the "ECMWF Data (Other Than Operational Data)" terms of acceptance during the registration process). Please note that RDA ERA-Interim data can be accessed by international users. It is recommended that all users read the Terms of Use in the next section.
Software Implementation Language N/A
Resource Support Name Dave Stepaniak
Resource Support Email davestep@ucar.edu
Resource Support Organization UCAR/NCAR - Research Data Archive
Distributor NCAR Research Data Archive
Metadata Contact Name N/A
Metadata Contact Email rdahelp@ucar.edu
Metadata Contact Organization NCAR Research Data Archive
Author European Centre for Medium-Range Weather Forecasts
Publisher Research Data Archive at the National Center for Atmospheric Research, Computational and Information Systems Laboratory
Publication Date 2009-02-17
Digital Object Identifier (DOI) https://doi.org/10.5065/D6CR5RD9
Alternate Identifier ds627.0
Resource Version N/A
Topic Category climatologyMeteorologyAtmosphere
Progress onGoing
Metadata Date 2019-09-09T13:05:02-07:00
Metadata Record Identifier edu.ucar.rda::ds627.0
Metadata Language eng; USA
Suggested Citation European Centre for Medium-Range Weather Forecasts. (2009). ERA-Interim Project. Research Data Archive at the National Center for Atmospheric Research, Computational and Information Systems Laboratory. https://doi.org/10.5065/D6CR5RD9. Accessed 21 September 2019.

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