Authors: Paul Berrisford, Anabelle Guillory, Michela Giusti, Kevin Marsh

Peer Review: Hans Hersbach, CUS team





Currently, the family of ERA5 datasets is comprised of ERA5, ERA5.1 and ERA5-Land.

  • ERA5 is a comprehensive reanalysis, from 1940 to 5 days behind real time, which assimilates as many observations as possible in the upper air and near surface. The ERA5 atmospheric model is coupled with a land surface model and a wave model.
  • ERA5.1 is a re-run for ERA5, for the years 2000 to 2006 only, which was produced to improve upon the lower stratospheric cold bias evident in ERA5 during this period. Behaviour of ERA5 in most of the troposphere is similar to that in ERA5.1.
  • ERA5-Land is a land surface dataset, from 1950 to 5 days behind real time, produced at higher resolution (9km) and forced by ERA5 atmospheric parameters with lapse rate correction, but with no additional data assimilation.

ERA5 back extension (preliminary version), from 1950 to 1978 was made available separately from ERA5.  Reason for this is it appeared to suffer from tropical cyclones that are sometimes unrealistically intense. This has now been resolved for 1950 to 1978. Access to this preliminary product was discontinued on August 15, 2023.

Usually, access to the family of ERA5 datasets is through the C3S Climate Data Store (CDS). The complete datasets are held in ECMWF's tape archive, MARS, but a sub-set of the datasets (all of the dataset for ERA5-Land) have been interpolated to a regular latitude, longitude grid and put on the CDS disks. Data access from the CDS disks is faster than from MARS, so if possible it is better to retrieve the data from the CDS disks. Please see the Climate Data Store (CDS) documentation for further details.

ERA5/ERA5-Land post-processed daily statistics (post-processed aggregated to daily time steps) are now also available to download from the Climate Data Store (CDS) either through the CDS web interface or the API service. Please note that daily aggregations are calculated during the retrieval process and are not part of a permanently archived dataset.

ERA5 hourly time-series data on single levels from 1940 to present is a subset of some parameters of the full CDS ERA5 single levels hourly dataset on 0.25 degrees resolution and is stored in Analysis Ready Cloud Optimised (ARCO) format, which has been implemented for retrieving long time-series for a single point in a efficient way. Because this dataset uses an alternative source for the ERA5 data designed for fast access long-timeseries for a single point, it is not recommended for operational use. Formats and structure of the data files are subject to change.

ERA5

  1. ERA5 data on CDS Disks - Fast access

The sub-set of data on the CDS disks comprises some single level parameters and pressure level parameters. The data are available hourly throughout the whole period. Monthly mean data are also available, in two forms: monthly means (of daily means) and monthly means for each hour of the day (synoptic monthly means). The CDS catalogue entries are:

2. ERA5 data on ECMWF MARS tapes - Slow access

The complete ERA5 dataset, at full resolution on the native grid, is stored in MARS. ERA5 data that has not been made available on the CDS disks includes:

  • ERA5 data on other level types i.e. model levels, potential temperature levels and one potential vorticity level, from 1940 to present (2 months in arrears). In addition, the last few months of data (up to 5 days in arrears) are kept online/cached and can be accessed much quicker than older data on tape.
  • Any other ERA5 parameters not listed on the CDS Download forms (e.g. some forecast parameters and ocean wave spectra)
  • ERA5.1 data for the years 2000 to 2006

Further documentation on ERA5 data is available here.

3. ERA5 post-processed  

ERA5 post-processed daily statistics (post-processed aggregated to daily time steps) are now also available to download from the Climate Data Store (CDS) either through the CDS web interface or the API service. Please note that daily aggregations of ERA5/ERA5-Land (on CDS Disks) are calculated during the retrieval process and are not part of a permanently archived dataset.

4. ERA5 hourly time-series data

ERA5 hourly time-series data on single levels is a subset of some parameters of the full CDS ERA5 single levels hourly dataset on 0.25 degrees resolution and is stored in Analysis Ready Cloud Optimised (ARCO) format, which has been implemented for retrieving long time-series for a single point in a efficient way. Please note that this dataset uses an alternative source for the ERA5 data designed for fast access long-timeseries for a single point, and it is not recommended for operational use. Formats and structure of the data files are subject to change.

ERA5-Land

For ERA5-Land, the data comprises some single level parameters.

The data are available hourly throughout the whole period. Monthly mean data are also available, in two forms: monthly means (of daily means) and monthly means for each hour of the day (synoptic monthly means). Daily aggregations of ERA5-Land are calculated during the retrieval process and are not part of a permanently archived dataset. The CDS catalogue entries are:

Further documentation on ERA5-Land data is available here.


 

This document has been produced in the context of the Copernicus Climate Change Service (C3S).

The activities leading to these results have been contracted by the European Centre for Medium-Range Weather Forecasts, operator of C3S on behalf of the European Union (Delegation Agreement signed on 11/11/2014 and Contribution Agreement signed on 22/07/2021). All information in this document is provided "as is" and no guarantee or warranty is given that the information is fit for any particular purpose.

The users thereof use the information at their sole risk and liability. For the avoidance of all doubt , the European Commission and the European Centre for Medium - Range Weather Forecasts have no liability in respect of this document, which is merely representing the author's view.

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