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Created by
Michela Giusti, last updated on Jul 16, 2026
8 minute read
Contributors: Marco Cucchi ( B-Open) , Vivien Mavel ( B-Open) , Chiara Cagnazzo (ECMWF), Marie-Louise John (ECMWF), Niclas Rieger (ECMWF)
Issued by: B-Open / Marco Cucchi
Issued Date: 12/12/2025
Ref: C3S2_420a_Provision_of_WFDE5_extension
Official reference number service contract: 2024/C3S2_420a_B-Open
Executive summary
The W5E5 dataset [1] was compiled to support the bias adjustment of climate input data for the impact assessments carried out in phase 3b of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP3b). It consists of 14 variables (see Table 1 ) with a daily temporal resolution on a regular longitude-latitude half-degree grid, with global spatial coverage. W5E5 is a merged dataset, which combines WFDE5 [2] data over land with ERA5 reanalysis [3] data over the ocean. In addition, it makes use of the Global Precipitation Climatology Project (GPCP) data [3] for precipitation data rescaling. Details about the different versions of the W5E5 dataset can be found in Table 2.
W5E5 v3.0 is distributed through the C3S Climate Data Store as monthly files in netCDF format. It uses a full half-degree grid (720 × 360 grid boxes) covering the whole globe. See Table 3 for a summary of all the input datasets used for W5E5 v3.0, and Table 4 for a description of of the dataset's general attributes.
Table 1: W5E5 variables summary
Name | Long name | Description | Units | Time coverage |
mask | WFDE5-ERA5 mask | A mask indicating whether the W5E5 data is derived from WFDE5 (1) or from ERA5 (0). | 1 | - |
orog | Surface altitude | The land surface altitude used for elevation corrections in WFDE5. | m | - |
sfcWind | Near-surface wind speed | The horizontal speed of the wind, or movement of air, at a height of 10 metres above the surface of the Earth. Values are derived from ERA5 near-surface wind speed. | m s-1 | 1979-01-01 to 2024-12-31 |
tas | Near-surface air temperature | The temperature of air at 2 metres above the surface of land, sea or inland waters. Values are derived from ERA5 2m air temperature with an elevation correction and bias correction using CRU mean monthly temperature and mean diurnal temperature range. | K | 1979-01-01 to 2024-12-31 |
tasmax | Daily maximum near-surface air temperature | Over land the W5E5 Daily maximum near-surface air temperature is the daily maximum of hourly WFDE5 Near-surface air temperature. Over the ocean, the W5E5 data is based on temporally (from hourly to daily resolution) and spatially (from 0.25° to 0.5° horizontal resolution) aggregated ERA5 Near-surface air temperature. | K | 1979-01-01 to 2024-12-31 |
tasmin | Daily minimum near-surface air temperature | Over land the W5E5 Daily minimum near-surface air temperature is the daily minimum of hourly WFDE5 near-surface air temperature. Over the ocean, the W5E5 data is based on temporally (from hourly to daily resolution) and spatially (from 0.25° to 0.5° horizontal resolution) aggregated ERA5 near-surface air temperature. | K | 1979-01-01 to 2024-12-31 |
ps | Surface air pressure | The pressure (force per unit area) of the atmosphere at the surface of land, sea and inland water. Values are derived from ERA5 surface air pressure with an elevation correction. | Pa | 1979-01-01 to 2024-12-31 |
psl | Sea level pressure | Over land the W5E5 Sea level pressure (psl) is the daily mean of hourly psl computed from hourly WFDE5 Surface altitude (orog), Surface air pressure (ps), and Near-surface temperature (tas) according to psl = ps * exp((g * orog) / (r * tas)), where g is gravity, and r is the specific gas constant of dry air. Over the ocean, W5E5 psl is based on temporally (from hourly to daily resolution) and spatially (from 0.25° to 0.5° horizontal resolution) aggregated ERA5 psl. | Pa | 1979-01-01 to 2024-12-31 |
huss | Near-surface specific humidity | The amount of moisture in the air divided by amount of air plus moisture at that location. Values are derived from ERA5 vapor pressure and saturation vapor pressure with an elevation correction. | kg kg-1 | 1979-01-01 to 2024-12-31 |
hurs | Near-surface relative humidity | Over land the W5E5 Near-surface relative humidity (hurs) is the daily mean of hourly hurs computed from hourly WFDE5 Near-surface specific humidity, Surface air pressure, and Near-surface air temperature using the equations of Buck (1981) as described in Buck (2010). Over the ocean, the W5E5 hurs is based on temporally (from hourly to daily resolution) and spatially (from 0.25° to 0.5° horizontal resolution) aggregated ERA5 hurs. | kg kg-1 | 1979-01-01 to 2024-12-31 |
rlds | Surface downwelling longwave radiation | The amount of thermal (also known as longwave or terrestrial) radiation emitted by the atmosphere and clouds that reaches a horizontal plane at the surface of the Earth. Values are derived from ERA5 surface downwelling longwave radiation with an elevation correction. | W m-2 | 1979-01-01 to 2024-12-31 |
rsds | Surface downwelling shortwave radiation | The amount of solar radiation (also known as shortwave radiation) that reaches a horizontal plane at the surface of the Earth. This parameter comprises both direct and diffuse solar radiation. Values are derived from ERA5 surface downwelling shortwave radiation and bias corrected using CRU cloud cover and effects of inter-annual changes in atmospheric aerosol loading. | W m-2 | 1979-01-01 to 2024-12-31 |
pr | Precipitation | Over land the W5E5 Precipitation (pr) is the daily mean of the sum of hourly WFDE5 rainfall and snowfall. Over the ocean, the W5E5 pr is based on temporally (from hourly to daily resolution) and spatially (from 0.25° to 0.5° horizontal resolution) aggregated ERA5 Precipitation. | kg m-2 s-1 | 1979-01-01 to 2020-12-31 |
prsn | Snowfall flux | The rate of snow that falls to the Earth's surface. Values are derived from ERA5 total precipitation and snowfall and are bias corrected primarily using precipitation data from CRU and GPCC. | kg m-2 s-1 | 1979-01-01 to 2020-12-31 |
Table 2: W5E5 versions history
Versions | Observational datasets used | Software version used | Changes from previous version |
v3.0 | WFDE5 Python software v2.1.0 | - | |
v3.1 | WFDE5 Python software v2.1.2 |
|
Table 3: Input dataset
Dataset | Summary | Variables used |
ERA5 | ECMWF reanalysis product |
|
Near surface meteorological variables from 1979 to 2024 derived from bias-corrected reanalysis |
| |
Global Precipitation Climatology Project data |
|
Table 4: W5E5 dataset general attributes
Dataset attribute | Details |
Horizontal coverage | Global |
Horizontal resolution | 0.5° x 0.5° |
Vertical coverage | Surface |
Temporal coverage | Depends on variable (see Table 2) |
Temporal resolution | Daily |
File format | netCDF |
Data type | Grid |
Versions | v3.0 |
Algorithms Description
The algorithms used for the generation of W5E5 v3.0 are identical to the ones used for the generation of previous versions v1.0 and v2.0, and are described at [1] . For the generation of W5E5 v3.0, a Python implementation of these algorithm has been developed and used, and is available for download in the "Documentation" tab of the dataset's CDS catalogue entry.
Data Description
File naming convention
File names adhere to the following convention:
<var>_W5E5_<YYYYMM>_v<version>.nc,
where
<var>: variable name, as in Table 1
- <YYYYMM>: year and month (where applicable)
- <version>: W5E5 dataset version
As an example, possible file names are:
File content
Actual file content and dimensions size varies from month to month and depending on the variable, but the general file structure is constant and analogous to the following example:
netcdf tas_W5E5_201801_v3.0 {
dimensions:
lat = 360 ;
lon = 720 ;
time = 31 ;
variables:
double lat(lat) ;
lat:_FillValue = NaN ;
lat:long_name = "Latitude" ;
lat:standard_name = "latitude" ;
lat:units = "degrees_north" ;
lat:axis = "Y" ;
double lon(lon) ;
lon:_FillValue = NaN ;
lon:long_name = "Longitude" ;
lon:standard_name = "longitude" ;
lon:units = "degrees_east" ;
lon:axis = "X" ;
int64 time(time) ;
time:long_name = "Time" ;
time:standard_name = "time" ;
time:axis = "T" ;
time:units = "hours since 1900-01-01" ;
time:calendar = "proleptic_gregorian" ;
float tas(time, lat, lon) ;
tas:_FillValue = 1.e+20f ;
tas:units = "K" ;
tas:long_name = "Near-Surface Air Temperature" ;
tas:standard_name = "air_temperature" ;
// global attributes:
:title = "WFDE5 over land merged with ERA5 over the ocean (W5E5) version 3.0" ;
:institution = "Potsdam Institute for Climate Impact Research (PIK) & European Center for Medium Range Weather Forecast (ECMWF) under Copernicus Climate Change Service" ;
:project = "Inter-Sectoral Impact Model Intercomparison Project phase 3 (ISIMIP3)" ;
:contact = "ISIMIP cross-sectoral science team <info@isimip.org> <https://www.isimip.org>; ECMWF Support Portal <http://copernicus-support.ecmwf.int>" ;
:summary = "WFDE5 (with GPCC precipitation correction) over land merged with ERA5 (with GPCP precipitation correction) over the ocean for ISIMIP3" ;
:references = "Cucchi et al. (2020) <https://doi.org/10.5194/essd-12-2097-2020> and Lange et al. (2021) <https://doi.org/10.48364/ISIMIP.342217> for W5E5; Weedon et al. (2014) <https://dx.doi.org/10.1002/2014WR015638> and Cucchi et al. (2020) <https://doi.org/10.5194/essd-12-2097-2020> for WFDE5; Hersbach et al. (2020) <https://dx.doi.org/10.1002/qj.3803> and Copernicus Climate Change Service Climate Data Store (2017) <https://cds.climate.copernicus.eu/#!/home> for ERA5" ;
:version = "3.0" ;
:Conventions = "CF-1.7" ;
}
Known issues
Licence and Citation
The described dataset is distributed under the Licence to Use Copernicus Products. The corrections applied are based upon CRU TS 4.09, distributed under the Open Government Licence (OGL), and GPCP/v2.3 monthly, distributed under the GPCP product license.
If publishing using this dataset please cite [1], where a more detailed description of the dataset can be found.
References
[1] Lange, Stefan (2019): WFDE5 over land merged with ERA5 over the ocean (W5E5). V. 1.0. GFZ Data Services. https://doi.org/10.5880/pik.2019.023
[2] M. Cucchi, G. P. Weedon, A. Amici, N. Bellouin, S. Lange, H. M. Schmied, H. Hersbach, C. Buontempo, "WFDE5: bias-adjusted ERA5 reanalysis data for impact studies", Earth System Science Data, https://essd.copernicus.org/articles/12/2097/2020, 2020.
[3] Copernicus Climate Change Service (C3S), "ERA5: Fifth generation of ECMWF atmospheric reanalysis of the global climate", C3S Climate Data Store (CDS), 2017, https://cds.climate.copernicus.eu/.
