Aerosol CCI at ICARE

Project summary

The Aerosol-CCI project (2010-2013), part of the European Space Agency’s Climate Change Initiative (CCI), is designed to provide essential climate variables for aerosols from satellite data. The objective is to develop consistent algorithms for the production of long-term total column aerosol optical depth (AOD) datasets at several wavelengths, together with the Ångström exponent (AE) that roughly describes the particle size. Starting with 8 existing heritage algorithms applied to European Earth Observation sensors, analyses are conducted to qualify and improve the algorithms. Among the algorithms tested, four use AATSR (dual view, one synergetic with SCIAMACHY), three use MERIS (multi-spectral wider swath) and one uses PARASOL (multi-spectral, multi-angle, polarisation providing highest information content).

All 8 algorithms were applied to 1 month of global data to understand the major sensitivities to assumptions made in the inversion scheme. In a first experiment, a harmonized definition of 4 optical aerosol components was used in all algorithms. In a second experiment, a climatology of aerosol properties derived from a combination of model and sunphotometer observations as a priori information in the retrievals was introduced to understand the AOD sensitivity to assumptions on aerosol properties. A third experiment assessed the impact of using a common nadir cloud mask for AATSR and MERIS algorithms in order to characterize the sensitivity of the retrievals to remaining cloud contamination. The performance of the algorithms was assessed by comparing global daily gridded satellite data against daily average AERONET sunphotometer observations. A round robin exercise of “best” versions of these algorithms was then applied to 4 months of global data to identify mature algorithms, and finally one complete year (2008) of global data was processed.
Although it is planned to pursue the study to improve algorithms further, It was decided to apply the most efficient algorithm to the AATSR sensor series and to openly distribute the first 17 years of AOD record.

ICARE’s contribution

The ICARE Data and Services Center is responsible for processing and distribution of the PARASOL aerosol product, based on algorithms provided by LOA. ICARE also provides two MERIS aerosol products, based on algorithms provided by HYGEOS: one is a cloud-decontaminated version of the ESA standard product, the other is the ALAMO product over ocean. ICARE further supports the project with supplying a workspace where data providers share their products with the other partners, to facilitate product intercomparison and validation. ICARE also develops tools to facilitate product visualization, intercomparison and subsampling around validation sites.
All products produced by the Aerosol-CCI Team at the end of phase I of the project are openly distributed from ICARE (see Data Access section below).

Aerosol-CCI partners and products

Coordinating partner: DLR/FMI


    Participating algorithms:
    • MERIS Standard (ESA/Hygeos/ICARE)
    • AATSR ALAMO (Hygeos/ICARE)
    • OMI Absorbing Aerosol Index (KNMI)
  • Three products are provided for each algorithm:
    • Level-2 product: 10-km orbit-wise product in a sinusoidal grid
    • Daily 1-degree level-3 product in a plate-carrée grid
    • Monthly 1-degree level-3 product in a plate-carrée grid

Data Access

Access to the data is subject to the Data Policy below. Users can access the data through the Archive Web Interface and the SFTP server server, using the Aerosol-CCI generic account (username=cci; password=cci). Users may register to access the Aerosol-CCI products and other ICARE data sets using their own account.

Data Policy

The products provided on the ICARE server are openly and freely available. No warranty is given by their providers. Users are obliged to acknowledge the ESA Climate Change Initiative and in particular its Aerosol_cci project together with the individual service provider. We encourage interaction with the service providers on proper use of the products and would like to receive a copy of all reports and publications using the datasets. An offer of co-­authorship should be considered, if the CCI datasets constitute a major component of a scientific publication.
Publications using data from CCI / ICARE must include the following sentence: “ESA Climate Change Initiative — Aerosol_cci Project. Products obtained from ICARE Data and Services Center (”


For more information regarding product access, registration, or any technical information, please contact For questions about the Aerosol-CCI project, please contact the project coordinator Thomas Holzer-Popp. For science questions about the products, please contact original data providers as indicated below:

To be completed


de Leeuw, G., T. Holzer-Popp, S. Bevan, W. Davies, J. Descloitres, R. G. Grainger, J. Griesfeller, A. Heckel, S. Kinne, L. Klüser, P. Kolmonen, P. Litvinov, D. Martynenko, P. North, B. Ovigneur, N. Pascal, C. Poulsen, D. Ramon, M. Schulz, R. Siddans, L. Sogacheva, D. Tanré, G. E. Thomas, T. H. Virtanen, W. von Hoyningen Huene, M. Vountas, S. Pinnock: Evaluation of seven European aerosol optical depth retrieval algorithms for climate analysis, RSE-D-12-00843R1, 2013

Holzer-Popp, T., G. de Leeuw, D. Martynenkow, L. Klüser, S. Bevan, W. Davies, F. Ducos, J. L. Deuze, R. G. Graigner, A. Heckel, W. von Hoyningen-Huene, P. Kolmonen, P. Litvinov, P. North, C. A. Poulson, D. Ramon, R. Siddans, L. Sogacheva, D. Tanré, G. E. Thomas, M. Vountas, J. Descloitres, J. Griesfeller, S. Kinne, M. Schulz, and S. Pinnock: Aerosol retrieval experiments in the ESA Aerosol_cci project, AMTD-2013-13, 2013.