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Contributors: Else van den Besselaar (KNMI)
Issued by: KNMI/Else van den Besselaar
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Related documents
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The E-OBS dataset is provided on regular latitude-longitude grids with spatial resolutions of 0.1° and 0.25°, and has a daily resolution. The coverage of E-OBS spans much of the European continent, from northern Scandinavia to southern Spain and north Africa, and from Iceland into the Russian Federation at 40°E, but the coverage changes through time as the station coverage expands and decreases in time. The earliest maps for temperature, precipitation, sea level pressure and radiation in E-OBS start on 1 January 1950, while the maps for wind speed start on 1 January 1980. Full new versions of E-OBS are released twice a year and provisional monthly updates are provided through http://surfobs.climate.copernicus.eu/dataaccess/access_eobs_months.php. The latest version at the time of writing is v30v31.0e, but in this document various earlier versions are used to provide additional information. Except where mentioned explicitly, the difference between subsequent versions is that each version is based on time series from stations which provide 6 months of additional data compared to the previous version. In some cases, new station time series have been added.
ECA&D and E-OBS are the backbone for the Climate Data node of the Regional Climate Centre for WMO RA VI (Europe and the Middle East).
Main variables
Variable | Unit | Description |
Maximum temperature | °C | Daily maximum air temperature measured near the surface, usually at 2 metres above the surface. |
Mean temperature | °C | Daily mean air temperature measured near the surface, usually at 2 metres above the surface. |
Minimum temperature | °C | Daily minimum air temperature measured near the surface, usually at 2 metres above the surface. |
Precipitation amount | mm | Total daily amount of rain, snow and hail measured as the height of the equivalent liquid water in a square metre. The data sources for the precipitation are rain gauge data which do not have a uniform way of defining the 24-hour period over which precipitation measurements are made. Therefore, there is no uniform time period (for instance, 06 UTC previous day to 06 UTC today) which could be attached to the daily precipitation. |
Sea level pressure | hPa | Daily mean air pressure at sea level. In regions where the Earth's surface is above sea level, the surface pressure is used to compute the air pressure that would exist at sea level directly below, given a constant air temperature from the surface to the sea level point. |
Surface shortwave downwelling radiation | W/m2 | Daily mean flux of shortwave radiation (also known as solar radiation) measured at the Earth's surface. |
Relative Humidity | % | Daily mean relative humidity measured near the surface usually at a height of 2 metres. Relative humidity values relate to actual humidity and saturation humidity. Values are in the interval [0,100]. 0% means that the air in the grid cell is totally dry, whereas 100% indicates that the air in the cell is saturated with water vapour, defined with respect to saturation over water. |
Wind speed | m/s | Daily mean wind speed at 10 metres above the surface. |
Data access information
| Description | Link |
|---|---|
| E-OBS is available to users via the Climate Data Store | https://cds.climate.copernicus.eu/datasets/insitu-gridded-observations- |
| europe%20?tab=overview | |
| E-OBS is also available through the C3S2_311_Lot3 portal | https://surfobs.climate.copernicus.eu/dataaccess/access_eobs.php |
The underlying station dataset
The station data are provided by 87 88 participating institutions and the ECA&D dataset contains over 23700 25000 meteorological stations (status September 2024March 2025). Metadata of the time series, including the source and information about the meteorological stations are provided through the ECA&D website.
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Prior to the inclusion of E-OBS in the C3S Climate Data Store (CDS), a (voluntary) user registration system was in place which allowed the number of registered users to be tracked. Figure 2 shows the cumulative number of registered users from the start of this system (early 2009) and the number of new registered users per month. Figure 3 shows a pie chart of the user groups of ECA&D and E-OBS based on a survey from 2013, which shows that the use of E-OBS has spread beyond the climate community.
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The usual approach in the production of a gridded dataset is to determine the best or most likely values for the key parameters used to interpolate station values to values on a regular grid. With an ensemble version of the dataset, a number of these key parameters can be varied, producing a range of possible gridded datasets (referred to as the ensemble). The advantage of producing a dataset this way is that with an ensemble it can be easier to quantify the uncertainty in the grid box averages. Using standard statistical approaches this can be difficult as a number of the error components have spatial and temporal structures which are difficult to model. Where users require a single measure of the interpolated daily fields, then the "best guess" (ensemble mean) values should be used. However, the ensemble spread should always be consulted as the uncertainty of the gridded field varies across the domain, and is ultimately determined by the variations in station coverage. The individual ensemble members are mainly intended for users who require the uncertainty in the gridded fields to propagate through to various other applications. If a user requires rainfall data for hydrological modelling, then each of the ensemble members could be fed into the hydrological model. In this way, the uncertainty in the rainfall interpolation would propagate through to the hydrological model output. Subsequent versions of E-OBS are updated using recent data from the European national meteorological services and by the inclusion of new time series. Usually, the amount of input station data explains the differences between subsequent versions of E-OBS.
E-
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OBSv31.0e vs E-
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OBSv30.0e
E-OBSv30OBSv31.0e was released in September 2024 March 2025 and spans the period 1950-01-01 to 2024-0612-3031, while E-OBSv29OBSv30.0e was released in March September 2024 spanning 1950-01-01 to 20232024-1206-3130. The most important changes between these two versions is the amount of data that is used. Existing networks of synoptic, climatological and (manual) rain-gauge station data are updated with the latest measurements that are received directly from the national or regional meteorological services. The group of meteorological services that provide such frequent updates of these networks are those from Germany, Czech Republic, Bosnia and Herzegovina, Norway, Slovenia, Finland, Ireland, Estonia, Sweden, Luxembourg, Netherlands, Portugal, Spain, Switzerland, Italy (Emilia-Romagna, Valle d'Aoste, Lazio, Camania), Montenegro, Belgium, France, Denmark, UK, Hungary, Poland, Latvia, Austria and Catalonia (Spain). For the remaining countries, data from the network of synoptic stations is used to update the time series (as documented in section 2.3). The other main changes for E-OBSv30OBSv31.0e are:
- Included new stations and updates for HungarySpain
- Included new data and updates for France
- Updated data in Romania
- stations for regione Abruzzo, Italy
- Included new stations for regione Veneto, Italy
- Included new stations for regione Puglia, Italy
- Updated stations in regione Trentino, Italy
- Re-included data for relative humidity, wind speed and sea level pressure for PolandUpdated data for Austria
Minimum temperature
Figure 11 shows the difference in the annual mean climatology of daily mean temperature for the period 1991-2020 between E-OBS versions 3031.0e and 2930.0e. Figure 12 shows the seasonal mean differences between these two versions for the period Dec 1999 – Nov 2000.
Figure 11: Difference in annual mean climatology of daily minimum temperature [°C] for the period 1991-2020 between versions 3031.0e and 2930.0e.
Figure 12: Differences in seasonal means of daily minimum temperature [°C] for Dec 1999-Nov 2000 between versions 3031.0e and 2930.0e.
Mean temperature
Figure 13 shows the difference in the annual mean climatology of daily mean temperature for the period 1991-2020 between E-OBS versions 3031.0e and 2930.0e. Figure 14 shows the seasonal mean differences between these two versions for the period Dec 1999 – Nov 2000.
Figure 13: Difference in annual mean climatology of daily mean temperature [°C] for the period 1991-2020 between versions 3031.0e and 2930.0e.
Figure 14: Differences in seasonal means of daily mean temperature [°C] for Dec 1999-Nov 2000 between versions 3031.0e and 2930.0e.
Maximum temperature
Figure 15 shows the difference in the annual mean climatology of daily mean temperature for the period 1991-2020 between E-OBS versions 3031.0e and 2930.0e. Figure 16 shows the seasonal mean differences between these two versions for the period Dec 1999 – Nov 2000.
Figure 15: Difference in annual mean climatology of daily mean temperature [°C] for the period 1991-2020 between versions 3031.0e and 2930.0e.
Figure 16: Differences in seasonal means of daily mean temperature [°C] for Dec 1999-Nov 2000 between versions 3031.0e and 2930.0e.
Precipitation
Figure 17 shows the difference in the annual mean climatology of daily precipitation for the period 1991-2020 between E-OBS versions 3031.0e and 2930.0e. Figure 18 shows the seasonal mean differences between these two versions for the period Dec 1999 – Nov 2000.
Figure 17: Difference in annual mean climatology of daily precipitation [mm/day] for the period 1991-2020 between versions 3031.0e and 2930.0e.
Figure 18: Differences in seasonal means of daily precipitation [mm/day] for Dec 1999-Nov 2000 between versions 3031.0e and 2930.0e.
Sea level pressure
The new pressure data for Spain has been included as station level pressure instead of sea level pressure. Therefore sea level pressure for v31.0e is delayed. The following figures are still based on v30.0e and v29.0e. Figure 19 shows the difference in the annual mean climatology of daily mean sea level pressure for the period 1991-2020 between E-OBS versions 30.0e and 29.0e. Figure 20 shows the seasonal mean differences between these two versions for the period Dec 1999 – Nov 2000.
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Figure 20: Differences in seasonal means of daily mean sea level pressure [hPa] for Dec 1999-Nov 2000 between versions 30.0e and 29.0e.
Radiation
Radiation for v31.0e is delayed due to a longer calculation time. This will be added in the near future. Figure 21 shows the difference in the annual mean climatology of daily mean global radiation for the period 1991-2020 between E-OBS versions 29.0e and 28.0e. Figure 22 shows the seasonal mean differences between these two versions for the period Dec 1999 – Nov 2000.
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Figure 22: Differences in seasonal means of daily mean global radiation [W/m2] for Dec 1999-Nov 2000 between versions 29.0e and 28.0e.
Relative humidity
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New data has been included in Spain in version 31.0e. This new dataset contained a large number of new stations and humidity is now derived from 24 hourly values instead of 3 hourly values resulting in large differences in Spain compared to previous E-OBS verrsions. Figure 23 shows the difference in the annual mean climatology of daily mean relative humidity for the period 1991-2020 between E-OBS versions
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31.0e and
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30.0e. Figure 24 shows the seasonal mean differences between these two versions for the period Dec 1999 – Nov 2000.
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Figure 23: Difference in annual mean climatology of daily mean relative humidity [%] for the period 1991-2020 between versions 3031.0e and 2930.0e.
Figure 24: Differences in seasonal means of daily mean relative humidity [%] for Dec 1999-Nov 2000 between versions 3031.0e and 2930.0e.
Wind speed
As E-OBSv29.0e does not have wind speed, so the figures below show the differences between v30.0e and v28.0e. Figure 25 shows the difference in the annual mean climatology of daily mean wind speed for the period 1991-2020 between E-OBS versions 3031.0e and 2830.0e. Figure 26 shows the seasonal mean differences between these two versions for the period Dec 1999 – Nov 2000.
Figure 25: Difference in annual mean climatology of daily mean wind speed [m/s] for the period 1991-2020 between versions 3031.0e and 2830.0e.
Figure 26: Differences in seasonal means of daily mean wind speed [m/s] for Dec 1999-Nov 2000 between versions 3031.0e and 2830.0e.
Data licence
The data licence for E-OBS is more restrictive than for other CDS products. The background for this difference is explained, below.
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