1. Department of Geophysical Sciences, University of Chicago, Chicago, Illinois, USA
2. Max Planck Institute for Meteorology, Hamburg, Germany
3. Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado, USA
4. Earth and Environmental Systems Institute, College of Earth and Mineral Sciences, Pennsylvania State University, University Park, Pennsylvania, USA
5. Institut de Physique du Globe de Paris, Université Paris 7-Denis Diderot, Paris, France