Nikolaos Evangeliou, Norwegian Institute for Air Research, Atmospheric and Climate Research, Kjeller, Norway, Yves Balkanski, LSCE, CEA CNRS UVSQ, 91191, Gif sur Yvette, France, Gif-Sur-Yvette Cedex, France, Sabine Eckhardt, Norwegian Institute for Air Research, Atmospheric and Climate Research (ATMOS), Kjeller, Norway, Anne Cozic, Norman, OK, United States, Didier Hauglustaine, Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS-UVSQ, UMR8212, Gif-Sur-Yvette, France and Andreas Stohl, Norwegian Institute for Air Research, Kjeller, Norway