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This article describes how users can access the family of ERA5 datasets via the Climate Data Store (CDS) infrastructure.
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Any data in the CDS catalogue can be accessed in these two ways. And since such data is kept online, access is usually fast. Some parts of the ERA5 dataset are not listed in the CDS catalogue. These are only accessible through the CDS API service. An example is ERA5 model level data that resides in the ECMWF's MARS tape archive. The extraction of such data from tape can lead to significantly longer retrieval times than data that is available online.
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2 - Prerequisites
- Learn more about the family of ERA5 datasets, and browse through the ERA5 data documentation and ERA5-Land data documentation.
- CDS account - If you do not yet have a CDS account, please create one HERE.
- Accept the Copernicus licence by creating a test download using the CDS Download web form interface (see below).
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- Go to the C3S climate data store (CDS).
- Type 'ERA5' in the search box.
- Follow the ERA5 dataset title link of interest (there will be many more hits).
Currently there are eight online ERA5 and two ERA5-Land catalogue entries
- Each of these dataset catalogue entries includes the following tabs:
- Overview . This gives a description of the selected dataset and metadata information (e.g. spatial details, file format, variables, etc).
- Documentation . This provides links to detailed documentation about the dataset.
- Download data . This is a download web form.
- Go to the Download data tab to make your selection for ERA5 data retrieval. Using this web interface, you can:
- make selections as per your requirements. For your convenience only valid combinations will show; invalid combinations are greyed out interactively.
accept the data licence in the Terms of use section (in case you had not yet accepted it). You will only see this section after you have logged in.
Note You will need to do this regardless whether you are accessing data through the web interface or through the CDS API (see below).
Click on the button Submit Form at the bottom right to submit your data request (you must be logged in and have accepted the terms and conditions before submitting your request).
- You will now be redirected to the Your requests page.
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| Note | ||
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When requesting ERA5 data from the CDS in NetCDF (web or CDS API), users should not request ERA5 reanalysis atmospheric data, wave data, and ensemble data in one request. This is because the data has different spatial grids, which can cause issues for the current grib to NetCDF converter and produce incorrect results. |
Option B: Download ERA5 family data
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stored on MARS tape archive (no data selection can be made from the CDS download form) - SLOW ACCESS
Although some flavours of the ERA5 family data is not online in the CDS (i.e. not available through the interactive web download form), it is accessible through CDS API. This embraces ERA5-complete , and ERA5.1-complete and ERA5-complete-preliminary, which provide data in the 'raw' format as they were produced:
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- Open the MARS ERA5 catalogue
browse for discovery, and browse your way to the parameter level to build a request.
Info - More information on the available streams, product types and levels is available in the ERA5 data documentation.
- On the parameter level, use the left-mouse button and the shift key to select more than one field in one retrieval.
- The MARS catalogue only shows data for the final quality controlled data that is made available 2-3 months in arrear. However, data is also available from preliminary timely updates up to 5 days behind real time, using the same retrieval structure.
Note To retrieve MARS data efficiently (and get your data quicker!) you should retrieve all the data you need from one tape, then from the next tape, and so on.
As a rule of thumb everything shown on one page at parameter level in the MARS ERA5 catalogue is grouped together on one tape
- For analysis fields this is one month of data with respect to one particular level type (e.g. surface).
- For forecast fields on model levels this is limited to one single day.
Use the " View MARS request " feature - this will help you build your own CDS API Python script to retrieve the data through the CDS API.
Expand title Example: Download ERA5 model level analysis data (temperature) in the native spherical harmonics representation in GRIB format. Code Block #!/usr/bin/env python import cdsapi c = cdsapi.Client() c.retrieve('reanalysis-era5-complete', { # Requests follow MARS syntax # Keywords 'expver' and 'class' can be dropped. They are obsolete # since their values are imposed by 'reanalysis-era5-complete' 'date' : '2013-01-01', # The hyphens can be omitted 'levelist': '1/10/100/137', # 1 is top level, 137 the lowest model level in ERA5. Use '/' to separate values. 'levtype' : 'ml', 'param' : '130', # Full information at https://apps.ecmwf.int/codes/grib/param-db/ # The native representation for temperature is spherical harmonics 'stream' : 'oper', # Denotes ERA5. Ensemble members are selected by 'enda' 'time' : '00/to/23/by/6', # You can drop :00:00 and use MARS short-hand notation, instead of '00/06/12/18' 'type' : 'an', }, 'output') # Output file; in this example containing fields in grib format. Adapt as you wish.- Tailor your request to
- re-grid to the desired regular lat-lon resolution
- convert to NetCDF (works for regular grids only, i.e., so you need to use the 'grid' keyword as well)
select sub areas
Expand title Example to download model level ERA5 analysis data (temperature) for a given area at a regular lat/lon grid in NetCDF format. Code Block #!/usr/bin/env python import cdsapi c = cdsapi.Client() c.retrieve('reanalysis-era5-complete', { # Requests follow MARS syntax # Keywords 'expver' and 'class' can be dropped. They are obsolete # since their values are imposed by 'reanalysis-era5-complete' 'date' : '2013-01-01', # The hyphens can be omitted 'levelist': '1/10/100/137', # 1 is top level, 137 the lowest model level in ERA5. Use '/' to separate values. 'levtype' : 'ml', 'param' : '130', # Full information at https://apps.ecmwf.int/codes/grib/param-db/ # The native representation for temperature is spherical harmonics 'stream' : 'oper', # Denotes ERA5. Ensemble members are selected by 'enda' 'time' : '00/to/23/by/6', # You can drop :00:00 and use MARS short-hand notation, instead of '00/06/12/18' 'type' : 'an', 'area' : '80/-50/-25/0', # North, West, South, East. Default: global 'grid' : '1.0/1.0', # Latitude/longitude. Default: spherical harmonics or reduced Gaussian grid 'format' : 'netcdf', # Output needs to be regular lat-lon, so only works in combination with 'grid'! }, 'ERA5-ml-temperature-subarea.nc') # Output file. Adapt as you wish.
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For ERA5-complete preliminary back-extension (1950-1978, superseded now, users are advised to access the final release from 1940 instead) follow the same procedure as for era5-complete explained above, however:
edit the script to change:
| Code Block |
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'reanalysis-era5-complete' to 'reanalysis-era5-complete-preliminary-back-extension'
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Data is available for the years 1950-1978 inclusive - so make sure that your request dates are within this time period.
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| Info | ||
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This document has been produced in the context of the Copernicus Climate Change Service (C3S). | ||
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| Code Block | ||
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import cdsapi
c = cdsapi.Client()
c.retrieve('reanalysis-era5-complete-preliminary-back-extension', { # Please note the name of the dataset
# Keywords 'expver' and 'class' can be dropped. They are obsolete
# since their values are imposed by 'reanalysis-era5-complete-preliminary-back-extension'
'date': '1970-01-01', # Valid range: 1950-01-01 to 1978-12-31.
'levelist': '1/2/3/4/5', # Model levels from 1 to 5
'levtype': 'ml',
'param': '130.128', # Full information at https://apps.ecmwf.int/codes/grib/param-db/
'stream': 'oper', # Hourly data.
'type': 'an',
'grid': '1.0/1.0', # Latitude/longitude grid resolution.
'time':'00/to/23', # You can drop :00:00 and use MARS short-hand notation, instead of '00/06/12/18', full information at https://confluence.ecmwf.int/pages/viewpage.action?pageId=118817378
'format':'netcdf', # Output needs to be regular lat-lon, so only works in combination with 'grid'!
}, 'era5.preliminary-back-extension-temperature-monthly-mean.nc') |
| title | Example to download ERA5 back extension (preliminary 1950-1978) monthly mean temperature at 50 hPa at a regular lat/lon grid in NetCDF format |
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| Code Block |
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#!/usr/bin/env python
import cdsapi
c = cdsapi.Client()
c.retrieve('reanalysis-era5-complete-preliminary-back-extension', { # Please note the name of the dataset
# Keywords 'expver' and 'class' can be dropped. They are obsolete
# since their values are imposed by 'reanalysis-era5-complete-preliminary-back-extension'
'date': '1964-01-01', # Valid range: 1950-01-01 to 1978-12-31. Always first of the month for monthly means
'levelist': '50', # Pressure level at 50 hPa
'levtype': 'pl',
'param': '130.128', # Full information at https://apps.ecmwf.int/codes/grib/param-db/
'stream': 'moda', # Monthly means (of Daily means).
'type': 'an',
'grid' : '1.0/1.0', # Latitude/longitude grid resolution.
'format' : 'netcdf', # Output needs to be regular lat-lon, so only works in combination with 'grid'!
}, 'era5.preliminary-back-extension-temperature-monthly-mean.nc')
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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 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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