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The regional air quality production of the Copernicus Atmosphere Monitoring Service (CAMS) is based on an ensemble of 11 state-of-the-art numerical air quality models developed in Europe : CHIMERE from INERIS (France), EMEP from MET Norway (Norway), EURAD-IM from Jülich IEK (Germany), LOTOS-EUROS from KNMI and TNO (Netherlands), MATCH from SMHI (Sweden), MOCAGE from METEO-FRANCE (France), SILAM from FMI (Finland), DEHM from AARHUS UNIVERSITY (Denmark), GEM-AQ from IEP-NRI (Poland), MONARCH from BSC (Spain) and MINNI from ENEA (Italy).

The regional air quality models provide two streams of regional reanalyses every year of the main atmospheric pollutants concentrations, in the lowest layers of the atmosphere for the European domain (east boundary=25.0° W, west=45.0° E, south=30.0° N, north=72.0°). Their horizontal resolution is 0.1° approximately from 3 km (at 72.0°N) to 10 km (at 30°N), allowing background air pollution levels and medium-range atmospheric composition to be monitored. To get insight into your local area, please liaise with your national or local air quality agency.

Two streams of regional European reanalyses are produced every year:

1) “interim” re-analyses are data assimilated fields of air pollutant concentrations, based on up-to-date observation data. Since October 1st, 2015, according to EU Decision 2011/850/EU on reciprocal exchange of information and reporting on ambient air quality, EU Member States must report to the European Environment Agency (EEA) observation data as soon as it is produced, even if the necessary validation process is not completed. Such data is thus flagged as “non-validated” or “non- verified” data. Up-to-Date (UTD) data should be considered as provisional or “interim” data, until they are flagged as “validated” by the Member States, which can formally happen more than one year after their production.

2) ‘validated’ reanalyses are data assimilated fields of air pollutant concentrations based on observation data rigorously validated according to the air quality reporting principles set in EU Decision 2011/850/EU on reciprocal exchange of information and reporting on ambient air quality. These data are reported by the Member States to the European Environment Agency (EEA) in autumn, every year for the previous year. 

The same post-processing are operated on these two streams.

Reanalyses from all partner models are combined in calculating the median value of the individual outputs, which currently gives the best estimate from the ensemble. In that case the median value is designated as the ENSEMBLE output.

Please note that access to the numerical data produced by the production chains of the individual models and the ENSEMBLE output is subject to your prior acceptance of the Licence agreement and registration (read more here for licence and here for registration).

Air quality models and data assimilation system

The nine air quality models use the meteorological parameters settings coming from operational ECMWF IFS, the boundary conditions for chemical species coming from IFS global production, the emissions coming from CAMS emission (for anthropic emissions over Europe and for biomass burning). 

Table 1: Air quality models (Source: Regional Production, Updated documentation covering all Regional operational systems and the ENSEMBLE (01-2021) document)

EMEPMET Norway (Norway)
EURAD-IMJülich IEK (Germany)
LOTOS-EUROSKNMI and TNO (Netherlands)
SILAMFMI (Finland)

Data access

Data is available for download from the CAMS Atmosphere Data Store (ADS). CAMS ADS registered users can access the available data interactively through the CAMS European air quality reanalyses ADS download web interface and/or programmatically using the API as per instructions detailed here.

Data availability

The CAMS European air quality reanalyses is available for recent years. 

Interim reanalyses become available for whole year Y on May of year Y+1.

Validated reanalyses become available for whole year Y in November year Y+2.

Table 2: Next release dates (last update  )


Published on ADSPublished on ADSPublished on ADS***

Published on ADS

Published on ADS*

Published on ADS*

Published on ADS**

Published on ADS**

Published on ADSPublished on ADSPublished on ADSPublished on ADS***expected in 20252024expected in 20262025

*for surface O3, NO2,PM2.5 and PM10 concentrations from the ENSEMBLE only.

**for surface O3, NO2, CO,SO2, PM2.5 and PM10 concentrations from the ENSEMBLE only.

***Two more species are provided: Formaldehyde(HCHO) and Glyoxal(CHOCHO)


MATCH data are available for some type and years. Please check on the ADS for availability.

Spatial grid

Horizontal resolution of ENSEMBLE reanalyses is on a 0.1°× 0.1° regular latitude-longitude grid.

The eleven individual models have different native spatial grids (for details see Regional Production, Updated documentation covering all Regional operational systems and the ENSEMBLE (01-2021) document) and they are interpolated on the ensemble common regular grid for each time step of the hourly reanalyses.


It's worth noting that it was decided to harmonize grid definitions between the NRT production and the reanalyses production in 2022. 

From VRA2020 and IRA2022, the grid definition is:

700 x 420 gridpoints:
– from -24.95°E to 44.95°E
– from 30.05°N to 71.95°N 
– Resolution 0.1° x 0.1°

For all previous productions (to VRA2020 and IRA2022) the grid definition is :

701 x 421 gridpoints:
– from -25°E to 45°E
– from 30.0°N to 72°N 
– Resolution 0.1° x 0.1°

Temporal frequency

The yearly ensemble reanalyses is available with a Time resolution of 1 hour from step 1st January to the 31st of December.

Data format

Data are available in NetCDF format for the individual models outputs and for the ENSEMBLE outputs.

Level listings

Vertical levels: Surface, 50m,100m, 250m, 500m, 750m, 1000m, 2000m, 3000m, 5000m


100m and 750m were added up from VRA2020 and IRA2022.

Product listings

The following species could be considered experimental and without assessment and to be used with caution:

  • SIA
  • PANs
  • PM10_WF
  • PM25_tot
  • PM25_res
  • NH3
  • PM10 DUST

The land-sea mask field used to produce the regional air quality data is attached here below, already interpolated to a regular lat/lon grid of 0.1°x0.1°:



land-sea mask (netCDF4)


Table 3: List of parameters

Variable NameNetCDF UnitsVariable name in ADSNote
Ammoniaµg m-3


Carbon monoxideµg m-3carbon_monoxide
PM 10 Dust fractionµg m-3dustDust is fraction in PM10
Formaldehydeµg m-3formaldehydeavailable from IRA 2023 and VRA2021
Glyoxalµg m-3glyoxalavailable from IRA 2023 and VRA2021
Nitrogen dioxideµg m-3nitrogen_dioxide
Nitrogen monoxideµg m-3nitrogen_monoxide
Non-methane volatile compounds (VOCs)µg m-3non_methane_vocs
Ozoneµg m-3ozone
Particulate matter d < 10 µm (PM10)µg m-3particulate_matter_10um
Particulate matter d < 10 µm, wildfires only (PM10_WF)µg m-3


available from IRA 2021 and VRA2019
Particulate matter d < 2.5 µm (PM2.5)µg m-3particulate_matter_2.5um

Particulate matter d < 2.5 µm, anthropogenic total carbon (PM2.5_tot)

µg m-3


available from IRA2022 and VRA2020
Particulate matter d < 2.5 µm, anthropogenic residential carbon only (PM2.5_res)µg m-3


available from IRA2022 and VRA2020
Peroxyacyl nitrates (PANs)µg m-3peroxyacyl_nitrates
PM 2.5 Secondary inorganic aerosol (SIA)µg m-3secondary_inorganic_aerosol
Sulphur dioxideµg m-3sulphur_dioxide

In Situ Observations

In situ observations used as input into the CAMS regional services to constrain the regional forecast models. In situ observations are also used in the evaluation and quality assurance (EQA) of all CAMS products.

titleTable 1: In situ observations

Application in CAMSMeasured speciesNetworks
Input for regional servicesO3, NO2, SO2, CO, PM2.5, PM10EEA/EIONET
EQA of regional servicesO3, NO2, SO2, CO, PM2.5, PM10EEA/EIONETEMEP

Validation reports

Validation Reports for the CAMS reanalysis can be found on the CAMS Quality Assurance website .

How to acknowledge, cite and refer to the data

All users of data uploaded on the Atmosphere Data Store (ADS) must provide clear and visible attribution to the Copernicus programme and are asked to cite and reference the dataset provider.

(1) Acknowledge according to the licence to use Copernicus Products.

(2) Cite each dataset used:

  • Expand
    titleFor ENSEMBLE

    Institut national de l'environnement industriel et des risques (Ineris), Aarhus University, Norwegian Meteorological Institute (MET Norway), Jülich Institut für Energie- und Klimaforschung (IEK), Institute of Environmental Protection – National Research Institute (IEP-NRI), Koninklijk Nederlands Meteorologisch Instituut (KNMI), METEO FRANCE, Nederlandse Organisatie voor toegepast-natuurwetenschappelijk onderzoek (TNO), Swedish Meteorological and Hydrological Institute (SMHI), Finnish Meteorological Institute (FMI), Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA) and Barcelona Supercomputing Center (BSC) (2022): CAMS European air quality forecasts, ENSEMBLE data. Copernicus Atmosphere Monitoring Service (CAMS) Atmosphere Data Store (ADS).  (Accessed on <DD-MMM-YYYY>),!/dataset/cams-europe-air-quality-reanalyses?tab=overview

(3) Throughout the content of your publication, the dataset used is referred to as Author (YYYY) e.g. for Ensemble data:  INERIS et. al (2020)



This document has been produced in the context of theCopernicus Atmosphere Monitoring Service (CAMS).

The activities leading to these results have been contracted by the European Centre for Medium-Range Weather Forecasts, operator of CAMS on behalf of the European Union (Delegation 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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