Claus Zehner, European Space Agency, Villanueva De La Can, Spain, Pepijn Veefkind, Royal Netherlands Meteorological Institute, De Bilt, Netherlands, Diego G Loyola, German Aerospace Center (DLR), The Remote Sensing Technology Institute (IMF), Oberpfaffenhofen, Germany, Michel Van Roozendael, Royal Belgian Institute for Space Aeronomy, Brussels, Belgium and Jochen Landgraf, SRON Netherlands Institute for Space Research, Utrecht, Netherlands