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-Interim | ERA5 | |
|---|---|---|
| Period covered | 1979 - present | 1950 - present |
| Production Period | August 2006 – end 2018 | Jan 2016 – end 2017, then continued in near real-time |
| Assimilation system | IFS Cycle 31r2 4D-Var | IFS Cycle 41r2 4D-Var |
| Spatial resolution | 79 km globally, 60 levels to 0.1 hPa | 31 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 estimates | None | From a 10-member Ensemble of Data Assimilations (EDA) at 63 km resolution |
| Model input | As in operations (inconsistent SST) | Appropriate for climate (e.g. CMIP5 greenhouse gases, volcanic eruptions, SST and sea-ice cover) |
| Input observations | As in ERA-40 and from Global Telecommunication System | In addition, various newly reprocessed datasets and recent instruments that could not be ingested in ERA-Interim |
| Variational bias scheme | Satellite radiances | Also ozone, aircraft and surface pressure data |
| Satellite data | RTTOV-7, clear-sky, 1D-VAR rainy radiances | RTTOV-11, all-sky for various components |
| New parameters | ERA-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 parameters | Accumulated from the beginning of the forecast | Accumulated from previous post-processing |
| Product main page | http://www.ecmwf.int/en/research/climate-reanalysis/era-interim | http://climate.copernicus.eu/climate-reanalysis |
| Technical documentation | Berrisford 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 |
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