Pierre-Yves Tournigand, Valeria Cigala, Università degli Studi di Padova, Italy; Alfredo J. Prata, AIRES Pty Ltd., Australia; Andrea K. Steiner, Gottfried Kirchengast, Wegener Center for Climate and Global Change (WEGC), Institute for Geophysics, Astrophysics, and Meteorology/Institute of Physics, University of Graz, Austria; Hugues Brenot, Royal Belgium Institute for Space Aeronomy, Belgium; Lieven Clarisse, Université libre de Bruxelles (ULB), Belgium; Riccardo Biondi, Università degli Studi di Padova, Italy