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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 v27v28.0e, 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/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 84 85 participating institutions and the ECA&D dataset contains over 23000 23300 meteorological stations (status April September 2023). 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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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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OBSv28.0e vs E-
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OBSv27.0e
E-OBSv27OBSv28.0e was released in April October 2023 and spans the period 1950-01-01 to 20222023-1206-3130, while E-OBSv26OBSv27.0e was released in October 2022 April 2023 spanning 1950-01-01 to 2022-0612-3031. 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 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 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-OBSv27OBSv28.0e are:
- New series included for Campania and Trentino in Italy
- Corrected elevation for German precipitation stations
- Included a large number of new stations and series for Denmark.
- Included a few new stations and series for Finland.
- Fixed a temperature problem for Polish temperature series.
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 2728.0e and 2627.0e. 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 mean temperature [°C] for the period 1991-2020 between versions 2728.0e and 2627.0e.
Figure 12: Differences in seasonal means of daily mean temperature temperature [°C] for Dec 1999-Nov 2000 between versions 2728.0e and 2627.0e.
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 2728.0e and 2627.0e. 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 2728.0e and 2627.0e.
Figure 14: Differences in seasonal means of daily mean temperature [°C] for Dec 1999-Nov 2000 between versions 2728.0e and 2627.0e.
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 2728.0e and 2627.0e. 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 2728.0e and 2627.0e.
Figure 16: Differences in seasonal means of daily mean temperature temperature [°C] for Dec 1999-Nov 2000 between versions 2728.0e and 2627.0e.
Precipitation
Figure 17 shows the difference in the annual mean climatology of daily precipitation for the period 1991-2020 between E-OBS versions 2728.0e and 2627.0e. 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 2728.0e and 2627.0e.
Figure 18: Differences in seasonal means of daily precipitation [mm/day] for Dec 1999-Nov 2000 between versions 2728.0e and 2627.0e.
Sea level pressure
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 2728.0e and 2627.0e. Figure 20 shows the seasonal mean differences between these two versions for the period Dec 1999 – Nov 2000.
Figure 19: Difference in annual mean climatology of daily mean sea level pressure [hPa] for the period 1991-2020 between versions 2728.0e and 2627.0e.
Figure 20: Differences in seasonal means of daily mean sea level pressure [hPa] for Dec 1999-Nov 2000 between versions 2728.0e and 2627.0e.
Radiation
Figure 21 shows the difference in the annual mean climatology of daily mean global radiation for the period 1991-2020 between E-OBS versions 2728.0e and 2627.0e. Figure 22 shows the seasonal mean differences between these two versions for the period Dec 1999 – Nov 2000.
Figure 21: Difference in annual mean climatology of daily mean global radiation [W/m2] for the period 1991-2020 between versions 2728.0e and 2627.0e.
Figure 22: Differences in seasonal means of daily mean global radiation [W/m2] for Dec 1999-Nov 2000 between versions 2728.0e and 2627.0e.
Relative humidity
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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28.0e and
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27.0e. 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 2728.0e and 2627.0e.
Figure 24: Differences in seasonal means of daily mean relative humidity [%] for Dec 1999-Nov 2000 between versions 2728.0e and 2627.0e.
Wind speed
Figure 25 shows the difference in the annual mean climatology of daily mean wind speed for the period 1991-2020 between E-OBS versions 2728.0e and 2627.0e. 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 2728.0e and 2627.0e.
Figure 26: Differences in seasonal means of daily mean wind speed [m/s] for Dec 1999-Nov 2000 between versions 2728.0e and 2627.0e.
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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