A joint effort to deliver satellite retrieved atmospheric CO2 concentrations for surface flux inversions
The ensemble median algorithm EMMA


Since long time, climate modellers use ensemble approaches to calculate the ensemble median and to estimate uncertainties of climate projections where no ground-truth is known. Following this idea, the ensemble median algorithm EMMA composes level 2 data of up to seven GOSAT and SCIAMACHY XCO2 retrievals independently developed by NASA (ACOS), NIES (operational product, PPDF), SRON (RemoteC), University of Leicester (UOL-FP), and the University of Bremen (BESD, WFMD). EMMA determines in 10x10 degree grid boxes monthly averages and selects the level 2 data of the median algorithm. Intelligent thresholds (depending on potential information content) prevent from over-weighting individual algorithms with a considerably larger amount of data.


EMMA, University of Bremen
Max Reuter (maximilian.reuter at iup.physik.uni-bremen.de)
Institute of Environmental Physics (IUP)
University of Bremen, FB1
Otto-Hahn-Allee 1
D-28334 Bremen
Phone: +49 (421) 218 62085
FAX: +49 (421) 218 4555

ACOS retrieval, NASA
Chris O'Dell (odell at atmos.colostate.edu)

BESD retrieval, University of Bremen
Max Reuter (maximilian.reuter at iup.physik.uni-bremen.de)

NIES operational retrieval
Yoshida Yukio (yoshida.yukio at nies.go.jp)

NIES PPDF-S retrieval
Andrey Bril (andrey.bril at gmail.com)

RemoTeC retrieval, SRON, KIT
Andre Butz (andre.butz at dlr.de)
Otto Hasekamp (o.p.hasekamp at sron.nl)

UoL-FP retrieval, University of Leicester
Hartmut Bösch (hb100 at leicester.ac.uk)

WFMD retrieval, University of Bremen
Oliver Schneising (schneising at iup.physik.uni-bremen.de)

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Data Access

The data access is password-restricted. Please use the following form to obtain username and password.





Please tell us in a few words (>3) what you plan with the data:

I agree with the conditions of use:

Please use the following link to access the data archive:

Till now, the EMMA data sets cover the period 01/2003-12/2018.

The data-format is NCDF.

Condition of Use

When using EMMA data, you agree ...

... to inform us prior to any publication where EMMA data products are planned to be used.

... to offer us co-authorship for any planned peer-reviewed publication based on EMMA data products. (For non peer-reviewed publications it is sufficient if you add an appropriate acknowledgement.)

... not to distribute the EMMA data products to any third party. The only exception being colleagues working in your institute (in this case you agree to inform them about the conditions listed here and that they also have to accept these conditions).


EMMA is in part funded by ESA/ESRIN (GHG CCI, ADVANSE), EU (MACC-II, MACC, CityZen, C3S), DLR (SADOS), and the state and the University of Bremen as well as participating institues and funding organizations.