|Title||GEMS data assimilation system for chemically reactive gases|
|Year of Publication||2009|
|Authors||Inness, A, Flemming, J, Suttie, M, Jones, L|
|Secondary Title||Technical Memorandum|
A data assimilation system for chemically reactive gases has been developed at the European Centre for Medium-Range Weather Forecasts (ECMWF) for the Global and regional Earth-system Monitoring using Satellite and in-situ data (GEMS) project. ECMWF's integrated forecast system (IFS) was extended to include the chemically reactive gases ozone, carbon monoxide, nitrogen oxides, formaldehyde and sulphur dioxide. Chemical transport models were coupled to the IFS using the OASIS4 coupler to model the chemical processes and to provide the IFS with chemical production and loss rates. This paper describes the assimilation system for the reactive gases, presents the background error statistics developed for the reactive gases, and shows some first results of the assimilation of satellite retrievals for all five new species.