Please be aware that the generation of this dataset is using an alternative source for the ERA5-land data and may be subject to changes over time (e.g. file format, data file structure, deprecation etc). This dataset should therefore be regarded as “experimental” and is not recommended for use in a production environment.
Notification of changes via the catalogue entry warning banner and/or in the Forum will be provided on best efforts.
Introduction
ERA5-Land is a reanalysis dataset providing a consistent view of the evolution of land variables over several decades at an enhanced resolution compared to ERA5. It covers the period from January 1950 to the present with hourly sampling and continues to be extended forward with 5 days behind real time.
This dataset presented here is a subset of some parameters of the full CDS ERA5-Land single levels hourly dataset on 0.1 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 an efficient way.
Methodology
The process to generate this dataset involves:
- Fetching ERA5-Land data in GRIB format.
- Apply homogenization conventions, as applicable:
- Rename spatial coordinates to latitude, longitude.
- Ensure latitude, longitude ranges are between [-90, +90], [-180, +180].
- If the number of hourly samples is incomplete (less than 24) the date is skipped (e.g. 1950-01-01).
- Time is expressed in one single dimension called time, which in ERA5-Land netCDFs is usually called valid_time.
- Drop "number", "step", "surface", "valid_time" and "depthBelowLandLayer".
- The accumulation variables (e.g. Total precipitation) are de-accumulated* to hourly resolution.
- Written to an ARCO Zarr archive (which is similar in structure to netCDF).
- The CDS requests the data from the Zarr archive using xarray and writes the data to netCDF or CSV (as requested).
(*) De-accumulation is the process of substracting to each hourly time sample its previous sample so that the final value expresses only the magnitude for that hour, and not for that hour plus the previous ones. The process takes into account the accumulation period of 24 hours, so that the first sample of every period is left as it is.
Data organization and access
The ARCO data is stored as Zarr datacubes.
The data is now available from the Climate Data Store (CDS), either interactively through its download web form or programmatically using the CDS API service:
ERA5-Land hourly time-series data on single levels from 1950 to present.
Spatial grid
The atmospheric parameters have a grid resolution of 0.1 degrees.
Please be aware when you select a "Location" on the form, the latitude and longitude values are rounded to the closest neighbourhood point of the 0.1 degrees grid.
Temporal frequency
Temporal frequency of the data is hourly and every day has 24 hourly steps.
Data format
In the CDS, there are the options of retrieving the data in NetCDF format or CSV format.
Parameters are stored in groups to ensure a proper access performance. The number of NetCDF files downloaded will be equal to total number of groups of all the parameters selected. Users can check the groups in the Parameters listings section below.
The file naming convention is:
reanalysis-era5-land-timeseries-sfc-groupnamerandomcharacters.[nc|csv]
Data update frequency
ERA5-Land is updated on a daily basis. New daily data in ERA5-Land becomes available in ERA5-Land hourly time-series in a few hours.
The availability of the data is of 5 days behind the actual date, this means that on the 24/04 users can download data for that day - 5 days = 19/04.
Variations in delivery times may occur due to the non-operational nature of this CDS service, as issues may arise which cause delays.
Parameters listings
Table 1 below lists the surface and single level parameters (levtype=sfc).
Table 1: surface and single level parameters (instantaneous and accumulations)
| Count | Name | Units | Variable name | Notes | Group |
|---|---|---|---|---|---|
1 | 2 metre temperature | K | 2m_temperature | 2m temperature | |
| 2 | 2 metre dewpoint temperature | K | 2m_dewpoint_temperature | 2m temperature | |
| 3 | Total precipitation | m | total_precipitation | De-accumulated | Pressure and precipitation |
| 4 | Surface pressure | Pa | surface_pressure | Pressure and precipitation | |
| 5 | 10 metre V wind component | m s**-1 | 10m_v_component_of_wind | Wind | |
| 6 | 10 metre U wind component | m s**-1 | 10m_u_component_of_wind | Wind | |
| 7 | Surface solar radiation downwards | J m**-2 | surface_solar_radiation_downwards | De-accumulated | Radiation and heat |
| 8 | Volumetric soil water layer 1 | m**3 m**-3 | volumetric_soil_water_layer_1 | Soil water | |
| 9 | Volumetric soil water layer 2 | m**3 m**-3 | volumetric_soil_water_layer_2 | Soil water | |
| 10 | Volumetric soil water layer 3 | m**3 m**-3 | volumetric_soil_water_layer_3 | Soil water | |
| 11 | Volumetric soil water layer 4 | m**3 m**-3 | volumetric_soil_water_layer_4 | Soil water | |
| 12 | Soil temperature level 1 | K | soil_temperature_level_1 | Soil temperature | |
| 13 | Soil temperature level 2 | K | soil_temperature_level_2 | Soil temperature | |
| 14 | Soil temperature level 3 | K | soil_temperature_level_3 | Soil temperature | |
| 15 | Soil temperature level 4 | K | soil_temperature_level_4 | Soil temperature | |
| 16 | Snow cover | % | snow_cover | Snow |
Known issues
Please refer to the ERA5-Land documentation.
References
Further ERA5 references are available from the ECMWF website.
Related articles
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How to download ERA5 (Copernicus Knowledge Base)
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