John T Sullivan¹, Arnoud Apituley², Thomas J McGee¹, Larry Twigg¹, Grant K. Sumnicht¹, Marc Allaart², Ankie Piters², Michel Van Roozendael³, Pepijn Veefkind², Johan Dehaan² and Karin Kreher⁴, (1)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (2)Royal Netherlands Meteorological Institute, De Bilt, Netherlands, (3)Royal Belgian Institute for Space Aeronomy, Brussels, Belgium, (4)BK Scientific, Mainz, Germany