[1] DLR Inst Atmospher Phys, Oberpfaffenhofen, Germany
[2] Univ Padua, Dept Phys & Astron, Padua, Italy
[3] Univ Leicester, Dept Phys & Astron, Leicester, Leics, England
[4] European Space Agcy, Estec, Noordwijk, Netherlands
[5] DLR Inst Tech Phys, Stuttgart, Germany
[6] NASA, Jet Prop Lab, Pasadena, CA USA
[7] NASA, Goddard Space Flight Ctr, Greenbelt, MD USA