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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 v26v29.0e, 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. |
The underlying station dataset
Data access information
| Description | Link |
|---|---|
| E-OBS is available to users via the Climate Data Store | https://cds.climate.copernicus.eu/cdsapp#!/dataset/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 85 participating institutions and the The station data are provided by 82 participating institutions and the ECA&D dataset contains over 22600 23600 meteorological stations (status September 2022March 2024). 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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Figure 6: Precipitation [mm/day] on 21 January 1995 in E-OBSv4.0 (a) and 22 January 1995 (b). After a one day-shift of the Luxembourg precipitation series, a more realistic precipitation pattern was obtained (c). Problem noticed by a colleague from KNMI.b
An example where the gridding method of E-OBS was improved following feed-back from a user relates to the number of drizzle-days in E-OBSv8.0 (released April 2013). Drizzle-days are days with precipitation totals between 0.1 and 0.5mm/day. Figure 7 shows a distinct raster-like pattern in the number of drizzle days in E-OBSv8.0 on the rotated 0.22° grid. Following this feed-back, a modification was made to the method, which removed the raster-pattern from this metric. Note that these rotated grids are no longer available for E-OBSv18.0e and higher.
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Similarly, the global radiation dataset has been post-processed in the areas and in the periods where it suffers from unrealistic values. This problem occurs in areas and periods where the station network is of low density. Following a similar procedure to that for relative humidity, the same quality-control rules are applied to the grids as are applied to the stations. This means that any daily global radiation sum in each of the E-OBS ensemble members is set to missing where it falls below the 3% TOA (Top Of Atmosphere) level or exceeds the maximum expected global radiation at the earth surface on a clear sky day. The quality control procedure is detailed in ECA&D (2021). This additional post-processing is in place as of E-OBSv24.0e.
Known issues
There are a couple of known issues with the E-OBS dataset or in certain versions and/or for certain elements. These issues are given on the following page which is updated when needed: https://surfobs.climate.copernicus.eu/userguidance/known_issues_eobs.php
Comparison with other datasets
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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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OBSv29.0e vs E-
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OBSv28.0e
E-OBSv26OBSv29.0e was released in October 2022 March 2024 and spans the period 1950-01-01 to 20222023-0612-3031, while E-OBSv25OBSv28.0e was released in April 2022 October 2023 spanning 1950-01-01 to 20212023-1206-3130. 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 groups 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), Montenegro, Belgium, France, Denmark, UK, Hungary 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-OBSv26OBSv29.0e are:
- Several duplicate stations and series were corrected.
- Global radiation units for Luxembourg have been corrected.
- Missing data for France are now included correctly instead of as zeros.
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- Included new stations and updates for Ukraine, Portugal and Belgium
- Included data from Global Summary of the Day for southeast Europe
- Updated Polish precipitation series that were wrongly included
- Included radiation series for Trentino in Italy
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 29.0e and 28.0e. 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 29.0e and 28.0e.
Figure 12: Differences in seasonal means of daily minimum temperature [°C] for Dec 1999-Nov 2000 between versions 29.0e and 28.0e.
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 29.0e and 28.0e. 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 29.0e and 28.0e.
Figure 14: Differences in seasonal means of daily mean temperature [°C] for Dec 1999-Nov 2000 between versions 29.0e and 28.0e.
Maximum temperature
Figure 15 Figure 11 shows the difference in the annual mean climatology of daily mean temperature for the period 1991-2020 between E-OBS versions 2629.0e and 2528.0e. Figure 12 16 shows the seasonal mean differences between these two versions for the period Dec 1999 – Nov 2000.
Figure 1115: Difference in annual mean climatology of daily mean temperature [°C] for the period 1991-2020 between versions 2629.0e and 2528.0e.
Figure 1216: Differences in seasonal seasonal means of daily mean temperature temperature [°C] for Dec 1999-Nov 2000 between versions 2629.0e and 2528.0e.
Precipitation
Figure 13 17 shows the difference in the annual mean climatology of daily precipitation for the period 1991-2020 between E-OBS versions 2629.0e and 2528.0e. Figure 14 18 shows the seasonal mean differences between these two versions for the period Dec 1999 – Nov 2000.
Figure 1317: Difference in annual mean climatology of daily precipitation [mm/day] for the period 1991-2020 between versions 2629.0e and 2528.0e.
Figure 1418: Differences in seasonal means of daily precipitation [mm/day] for Dec 1999-Nov 2000 between versions 2629.0e and 2528.0e.
Sea level pressure
Figure 15 19 shows the difference in the annual mean climatology of daily mean sea level pressure for the period 1991-2020 between E-OBS versions 2629.0e and 2528.0e. Figure 16 20 shows the seasonal mean differences between these two versions for the period Dec 1999 – Nov 2000.
Figure
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19: Difference in annual mean climatology of daily mean sea level pressure [hPa] for the period 1991-2020 between versions
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29.0e and
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28.0e.
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Figure
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20: Differences in seasonal means of daily mean sea level pressure [hPa] for Dec 1999-Nov 2000 between versions
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29.0e and
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28.0e.
Radiation
Figure 17 21 shows the difference in the annual mean climatology of daily mean global radiation for the period 1991-2020 between E-OBS versions 2629.0e and 2528.0e. Figure 18 22 shows the seasonal mean differences between these two versions for the period Dec 1999 – Nov 2000.
Figure 1721: Difference in annual mean climatology of daily mean global radiation [W/m2] for the period 1991-2020 between versions 2629.0e and 2528.0e.
Figure 1822: Differences in seasonal means of daily mean global radiation [W/m2] for Dec 1999-Nov 2000 between versions 2629.0e and 2528.0e.
Relative humidity
Figure 19 23 shows the difference in the annual mean climatology of daily mean relative humidity for the period 1991-2020 between E-OBS versions 2629.0e and 2528.0e. Figure 20 24 shows the seasonal mean differences between these two versions for the period Dec 1999 – Nov 2000. 
Figure 1923: Difference in annual mean climatology of daily mean relative humidity [%] for the period 1991-2020 between versions 2629.0e and 2528.0e.
Figure 2024: Differences in seasonal means of daily mean relative humidity [%] for Dec 1999-Nov 2000 between versions 26.0e and 25.0e.
Wind speed
of daily mean relative humidity [%] for Dec 1999-Nov 2000 between versions 29.0e and 28.0e.
Wind speed
As E-OBSv29.0e does not have radiation ready at the time of writing (8 March 2024), the figures below show still the differences between v28.0e and v27.0e. Figure 25 Figure 21 shows the difference in the annual mean climatology of daily mean wind speed for the period 1991-2020 between E-OBS versions 2628.0e and 2527.0e. Figure 22 26 shows the seasonal mean differences between these two versions for the period Dec 1999 – Nov 2000.
Figure 2125: Difference in annual mean climatology of daily mean wind speed [m/s] for the period 1991-2020 between versions 2628.0e and 2527.0e.
Figure 2226: Differences in seasonal means of daily mean wind speed [m/s] for Dec 1999-Nov 2000 between versions 2628.0e and 2527.0e.
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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Van den Besselaar, E.J.M., van der Schrier and G., de Baar, J. (2021) Daily relative humidity maps for Europe based on in-situ observations (in preparation)
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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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