Volker Wilken¹, Martin Kriegel², Jens Berdermann², Claudio Cesaroni³, Luca Spogli⁴, Vincenzo Romano⁵, Nicolas Bergeot⁶, Jean-marie J Chevalier, Iwona M Stanislawska⁸, Lukasz Tomasik⁸ and Bert van den Oord⁹, (1)German Aerospace Centre, Neustrelitz, Germany, (2)German Aerospace Center Neustrelitz, Neustrelitz, Germany, (3)Istituto Nazionale di Geofisica e Vulcanologia, Palermo, Italy, (4)INGV National Institute of Geophysics and Volcanology, Rome, Italy, (5)SpacEarth Technology, Rome, Italy, (6)Royal Observatory of Belgium, Brussels, Belgium, (7)Space Research Center Polish Academy of Sciences, Warszawa, Poland, (8)Royal Netherlands Meteorological Institute, De Bilt, Netherlands