An OSSE to Study the Impact of S4/5 Spaceborne Observations on Air Quality Data Assimilation Systems
Eskes, Henk¹; Veefkind, Pepijn¹; Williams, Jason¹; Oude Nijhuis, Albert¹; de Haan, Johan¹; Attie, Jean-Luc²; Abida, Rachid²; Ricaud, Philippe²; El Amraoui, Laaziz²; Curier, Lyana³; Segers, Arjo³; Kujanpaa, Jukka⁴; Tamminen, Johanna⁴; Lahoz, William⁵; Schuettemeyer, Dirk⁶; Veihelmann, Ben^6
1KNMI, NETHERLANDS; ²CNRM-GAME, FRANCE; ³TNO, NETHERLANDS; ⁴FMI, FINLAND; ⁵NILU, NORWAY; ⁶ESA, NETHERLANDS

ISOTROP (Impact of Spaceborne Observations on Tropospheric Composition Analysis and Forecast) is an ESA funded OSSE study. It's aim is to quantify the impact of sentinel 4 (GEO) and 5 (LEO) measurements of ozone, CO, NO2 and HCHO to better constrain pollutant concentrations and precursor emissions that influence air quality. The work has started in June 2012, and we will describe the approach, plans and first results. The project is based on a cross-OSSE approach which involves two independent air quality models. Each of the models will generate the nature run for the other model, used subsequently in two linked OSSE studies. The models involved are MOCAGE, and the air quality model LOTOS-EUROS combined with the global TM5 chemistry-transport model. The work is based on state-of-the-art synthetic observations and their error characteristics derived by the KNMI and FMI teams involved in the TROPOMI retrieval algorithm development.