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ERA5 strengths compared to ERA-Interim

  • Much higher spatial and temporal resolution

  • Information on variation in quality over space and time

  • Much improved troposphere

  • Improved representation of tropical cyclones

  • Better global balance of precipitation and evaporation

  • Better precipitation over land in the deep tropics

  • Better soil moisture

  • More consistent sea surface temperature and sea ice

Comparison table

This table highlights major differences between ERA-Interim and ERA5. There are many additional differences, in particular changes to the computation of individual atmospheric parameters (due to the change in the assimilation system from 31r2 to 41r2) are not listed here.

 ERA-InterimERA5
Period covered1979 - present1950 - present
Production PeriodAugust 2006 – end 2018Jan 2016 – end 2017, then continued in near real-time
Assimilation systemIFS Cycle 31r2 4D-VarIFS Cycle 41r2 4D-Var
Spatial resolution79 km globally, 60 levels to 0.1 hPa31 km globally, 62km for the Ensemble of Data Assimilations (EDA), 137 levels to 0.01 hPa
Output frequency (temporal resolution)

6-hourly analysis fields

Forecast fields on surface and pressure levels 3-hourly up to 24 hours, with reduced frequency up to 10 days

Hourly analysis fields, 3-hourly for the Ensemble of Data Assimilations (EDA)

Hourly forecast fields, 3-hourly for the Ensemble of Data Assimilations (EDA), up to 18 hours, with reduced frequency up to 10 days (not in initial release)

Uncertainty estimatesNoneFrom a 10-member Ensemble of Data Assimilations (EDA) at 63 km resolution
Model inputAs in operations (inconsistent SST)Appropriate for climate (e.g. CMIP5 greenhouse gases, volcanic eruptions, SST and sea-ice cover)
Input observationsAs in ERA-40 and from Global Telecommunication SystemIn addition, various newly reprocessed datasets and recent instruments that could not be ingested in ERA-Interim
Variational bias schemeSatellite radiancesAlso ozone, aircraft and surface pressure data
Satellite dataRTTOV-7, clear-sky, 1D-VAR rainy radiancesRTTOV-11, all-sky for various components
New parametersERA-Interim contains about 100 parameters on surface and single level alone, plus parameters on other level types.

ERA5 contains over 240 parameters on surface and single level alone, plus parameters on other level types. For specific parameters please compare the technical documentation linked below.

Parameters removed


A few parameters present in ERA-Interim are not available in ERA5. For availability of specific parameters please see the technical documentation linked below.

Handling of accumulated parametersAccumulated from the beginning of the forecast

Accumulated from previous post-processing

Product main pagehttp://www.ecmwf.int/en/research/climate-reanalysis/era-interimhttp://climate.copernicus.eu/climate-reanalysis
Technical documentationBerrisford et al 2011: The ERA-Interim archive Version 2.0 ERA5 data documentation
Additional innovations Long-term evolution of CO2 in RTTOV, cell-pressure correction SSU, improved bias correction for radiosondes, EDA perturbations for sea-ice cover