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What is the MACC reanalysis?

The Monitoring Atmospheric Composition and Climate (MACC) Reanalysis is a global reanalysis data set of atmospheric composition (AC), made available by the Copernicus Atmosphere Monitoring Service (CAMS).  The dataset spans the period 2003 to 2012. The spatial resolution of the data set is approximately 80 km (T255 spectral) on 60 vertical levels from the surface up to 0.1 hPa for the analysed species and 1.125° by 1.125° at the same 60 levels for the other chemical species.

The MACC Reanalysis was constructed by assimilating satellite data into a global model and data assimilation system. This data assimilation system is based on a 2010 release of the Integrated Forecast System (IFS) (Cy36r1). The chemistry transport model MOZART (Model for OZone And Related chemical Tracers) was coupled to the IFS to provide initial fields and chemical production and loss rates for the reactive gases (Flemming et al. 2009). The system includes a 4-dimensional variational analysis (4D-Var) with a 12-hour analysis window and provides analysis fields of atmospheric composition species, namely ozone (O3), carbon monoxide (CO), nitrogen oxides (NOx), SO2, formaldehyde (HCHO), and aerosols, in addition to meteorological fields. Additional reactive gases species are available from the coupled chemistry transport model MOZART. 

The output of the reanalysis has been validated by the MACC-II VAL sub-project and the latest information is available in a validation report.

An open-access journal article describing the chemistry part of the MACC reanalysis is available from Atmospheric Chemistry and Physics (Inness et al. 2013). Inness et al. (2013) also lists which atmospheric composition data sets were assimilated in the MACC reanalysis.

We are aware of several quality issues with MACC reanalysis data (see known issues section below).

Known issues

Sea salt aerosol mixing ratio above freshwater: The model is not distinguishing between sea and freshwater in the context of sea-salt emissions.  Unfortunately, this appears to affect all cycles from the MACC reanalysis. A fix is planned to be implemented in a future model release (45r1) and will be effective from the implementation date on. This means that the fix will not be retrospective for the MACC reanalysis but will be in future reanalysis.

Changes in biomass burning emissions: The biomass burning emissions were changed on 1 January 2009 from a preliminary version of GFED3 to GFAS version 1.0. The GFAS version 1.0 emissions budget is about 18 % higher than those used during the first 6 yr.

MOPITT CO data: After 23 March 2010 NRT MOPITT CO data were used in the reanalysis instead of the offline product. This change did not have a noticeable impact on the reanalysis fields.

Assimilation of IASI CO: Assimilation of IASI CO after 1 April 2008 led to some changes in the CO field.

Tropospheric O3: Using variational bias correction for MLS ozone profiles led to increased tropospheric ozone and changes to ozone above 15 hPa. However, it did not affect the total column ozone field. These drifts stopped on 1 January 2008 when the bias correction was switched off for MLS, and afterwards agreement with independent ozonesondes and MOZAIC data was improved.

O3 in UTLS: Using NRT MLS data instead of the offline product after 16 March 2009 resulted in larger departures in the upper troposphere and lower stratosphere, because the lowest 3 layers (68–100, 100–146, and 146–215 hPa) of the MLS data could not be used.

OMI O3: NRT OMI ozone columns were assimilated instead of the offline product between 21 March 2007 and 31 December 2007. This did not have a noticeable impact on the ozone analysis.

MOZART model upgrade: A model upgrade to MOZART 3.5 was implemented on 1 January 2009, which slightly improved the representation of the ozone hole in the control run but did not affect the other model fields.

SCIAMACHY NO2: NO2 SCIAMACHY retrievals V1.04 were assimilated until 30 June 2007, SCIAMACHY V1.1 data were assimilated after 11 September 2007, but this only has a minor impact on the analysis fields.

How to cite MACC reanalysis data

Please acknowledge the use of MACC Reanalysis data as per MACC Reanalysis Licence Agreement

Dataset citable as:  MACC-II Consortium, 2011: MACC Reanalysis of Global Atmospheric Composition (2003-2012). Copernicus Atmosphere Monitoring Service (CAMS), date of citation.


  • Flemming, J., A. Inness, H. Flentje, V. Huijnen, P. Moinat, , M. G. Schultz, and O. Stein, 2009: Coupling global chemistry transport models to ECMWF's integrated forecast system, Geosci. Model Dev., 2, 253-265,
  • Flemming, J., and A.Inness, 2013: Volcanic sulfur dioxide plume forecasts based on UV satellite retrievals for the 2011 Grímsvötn and the 2010 Eyjafjallajökull eruption, J. Geophys. Res. Atmos., 118, 10,172–10,189,
  • Inness, A., and Coauthors, 2013: The MACC reanalysis: an 8 yr data set of atmospheric composition, Atmos. Chem. Phys., 13, 4073-4109,
  • Katragkou, E., and Coauthors, 2015: Evaluation of near-surface ozone over Europe from the MACC reanalysis, Geosci. Model Dev., 8, 2299-2314,
  • Lefever, K., and Coauthors, 2015: Copernicus stratospheric ozone service, 2009–2012: validation, system intercomparison and roles of input data sets, Atmos. Chem. Phys., 15, 2269-2293,
  • Wagner, A., and Coauthors, 2015: Evaluation of the MACC operational forecast system – potential and challenges of global near-real-time modelling with respect to reactive gases in the troposphere, Atmos. Chem. Phys., 15, 14005-14030,

This document has been produced in the context of the Copernicus 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.