ECMWF Reanalysis Products#

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Please contact data(at)dkrz.de for questions regarding ERA data in the /pool/data/ERA5 directory on Levante.

ERA ('ECMWF Re-Analysis') refers to a series of climate reanalysis datasets produced at the European Centre for Medium-Range Weather Forecasts (ECMWF). Climate reanalyses combine observations with models to generate consistent time series of multiple climate variables. Reanalysis time series are widely used as forcing fields in atmospheric models. ERA5 (ERA fifth generation) is the latest climate reanalysis which is produced by Copernicus Climate Change Service (C3S) at ECMWF. It covers the period from January 1940 to present and replaces ERA-Interim and other predecessor ERA datasets such as, e.g., ERA-40, ERA-15 and ERA-20C.

ERA5 data are produced with a spatial resolution of approximately 31 km, 137 vertical model levels and hourly time steps. It consists of analyses and short forecasts. ECMWF runs ERA5 forecasts twice daily from 06 and 18 UTC, providing hourly output forecast steps from 0 to 18 hours. ERA5 is available on single and model levels. In addition, data that are interpolated to 37 pressure levels or to potential temperature/vorticity are provided. Single or ‘surface’ level data encompass 2D parameters such as surface quantities (e.g., precipitation) or top of atmosphere radiation. There are more than 200 different parameters available for single level data, as well as 16 parameters for vertically resolved data. The final, quality-assured ERA5 product is archived on a spectral/reduced Gaussian grid (T639/N320) on the ECMWF MARS tape system.

Apart from the final ERA5 product, ECMWF has released two additional product variants: ERA5T and ERA5.1. ERA5T is a provisional, early-release version of the ERA5 data. ECMWF produces ERA5T with a ~3-day delay from real time, i.e. with much less delay compared to the 2-3 months for the release of the final, validated ERA5 data. ERA5T is superseded once the validated ERA5 data become available. ERA5.1 is an improved re-run of ERA5 for the years 2000 to 2006 as it corrects for the pronounced cold bias in the lower stratospheric temperature observed during that period (see Simmons et al., 2020). ERA5.1 shows significant differences to ERA5 only in the upper troposphere/stratosphere and only for certain variable s.

As a service to DKRZ users, DKRZ makes a comprehensive subset of the ERA5, ERA5T and ERA5.1 data available on the HPC system Levante through its data pool at /pool/data/ERA5. The subset comprises model (ml) and pressure level (pl) data for all 16 parameters, and single level data (sf) for around 100 parameters. Only ERA5 analysis (‘an’) are provided. The exception are surface parameters where ERA forecasts (‘fc, steps 1 to 12 hours’) are made available in addition to ERA analysis. Besides hourly resolution data (1H), daily (1D) and monthly (1M) aggregated data are made accessible. Also some time-invariant data (IV) are provided. All files are stored in GRIB format.

Users can access the final ERA5 data on Levante via /pool/data/ERA5/E5. That directory contains the ERA5 time series starting from January 1940. DKRZ staff regularly updates the available time series to extend them forward in time. Updates of ERA5 typically lag 3 months behind real time. ERA5T data are provided on /pool/data/ERA5/ET with a 2-3 day delay from real time. ERA5T files are being deleted whenever the corresponding final ERA5 files are made available on /pool/data/ERA5/E5. ERA5.1 data for the period 2000 to 2006 are provided on /pool/data/ERA5/E1.

File and Directory Names#

A consistent directory structure and file naming conventions has been implemented.

The directory structure is as follows:

/pool/data/ERA5/${FAMILY}/${LEVEL}/${TYPE}/${TRES}/${PARAM}

The file naming convention is as follows:

${FAMILY}${LEVEL}${TYPEID}_${TRES}_${DATE}_${PARAM}.grb

with

FAMILY	(ERA family):
`E5`	Final ERA5 data starting from January 1940.
`ET`	ERA5-T: Provisional, early-release ERA5 data. Only E1 of the last 4 months are provided.
`E1`	ERA5.1: Improved ERA5 re-run for the period 2000 to 2006.

LEVEL	(level type):
`sf`	Single (or ‘surface’) (sf) level analysis or forecast data
`ml`	Model level (ml) data (137 levels)
`pl`	Pressure level (pl) data (37 levels)

TYPE	(ECMWF type):
`an`	Analysis
`fc`	Forecast

TRES	(temporal resolution):
`1H`	Hourly resolution data
`1D`	Daily aggregated statistics
`1M`	Monthly means of daily aggregated statistics
`IV`	Time-invariant (static) data

TYPEID	(ECMWF type ID):
`00`	all data with ECMWF type (TYPE) = an
`12`	for data with ECMWF type (TYPE) = fc

DATE	(date stamp with YYYY = 4-digit year; MM = two-digit month; DD = 2-digit day):
`${YYYY}-${MM}-${DD}`	for TRES=1H
`${YYYY}-${MM}`	for TRES=1D
`${YYYY}`	for TRES=1M
`INVARIANT`	for TRES=IV

PARAM	(parameter code, derived from the WMO GRIB parameter table):
`PARAM <=256`	3-digit parameter ID of GRIB table 128
`PARAM >256`	256 + last 3-digits of parameter ID of GRIB table 228

For example, PARAM=259 corresponds to “friction velocity” which has the parameter ID 003 in GRIB table 228.

How to Use and Correctly Cite ERA5 Data?#

ERA5 data, which are produced as part of the EU-funded Copernicus Climate Change Service (C3S), are distributed on an open basis without any specific restrictions on their usage or distribution (see License). However, all users of Copernicus Products must provide clear and visible attribution to the Copernicus program. The citation for the ERA products distributed by DKRZ on Levante /pool/data/ERA5 is as follows:

ERA5 (E5 and ET):

Hersbach, H., Bell, B., Berrisford, P., Hirahara, S., Horányi, A., Muñoz‐Sabater, J., Nicolas, J., Peubey, C., Radu, R., Schepers, D., Simmons, A., Soci, C., Abdalla, S., Abellan, X., Balsamo, G., Bechtold, P., Biavati, G., Bidlot, J., Bonavita, M., De Chiara, G., Dahlgren, P., Dee, D., Diamantakis, M., Dragani, R., Flemming, J., Forbes, R., Fuentes, M., Geer, A., Haimberger, L., Healy, S., Hogan, R.J., Hólm, E., Janisková, M., Keeley, S., Laloyaux, P., Lopez, P., Lupu, C., Radnoti, G., de Rosnay, P., Rozum, I., Vamborg, F., Villaume, S., Thépaut, J-N. (2017): Complete ERA5 from 1940: Fifth generation of ECMWF atmospheric reanalyses of the global climate. Copernicus Climate Change Service (C3S) Data Store (CDS). DOI: 10.24381/cds.143582cf (Accessed on 15-JUN-2023). Data distribution by the German Climate Computing Center (DKRZ).

ERA5.1 (E1):

Simmons, A., Soci, C., Nicolas, J., Bell, B., Berrisford, P., Dragani, R., Flemming, J., Haimberger, L., Healy, S., Hersbach, H., Horányi, A., Inness, A., Munoz-Sabater, J., Radu, R., Schepers, D. (2020): ERA5.1: Rerun of the Fifth generation of ECMWF atmospheric reanalyses of the global climate (2000-2006 only). Copernicus Climate Change Service (C3S) Data Store (CDS). DOI: 10.24381/cds.143582cf (Accessed on 02-FEB-2023). Data distribution by the German Climate Computing Center (DKRZ).

Further Information on ERA Data#

More detailed information on the data can be found in:

the README files in /pool/data/ERA5/READMEs
The ECMWF ERA5 data documentation provides detailed explanations on ERA5 parameters, space and time properties and many more topics.

Other ERA Products#

In addition to holding ERA5 data on Levante /pool/data directory, DKRZ distributes the following ERA datasets via the WDCC data repository:

last updated 2023-06-23 by A. Heil