Sönke Dangendorf, University of Siegen, Research Institute for Water and Environment, Siegen, Germany; Old Dominion University, Ocean, Earth & Atmospheric Sciences, Norfolk, United States, Leon Chafik, Stockholm University, Department of Meteorology, Stockholm, Sweden, Christopher G Piecuch, Atmospheric and Environmental Research Lexington, Lexington, MA, United States and Thomas Frederikse, NASA Jet Propulsion Laboratory, Pasadena, CA, United States