1. Institute of Applied Physics of Russian Academy of Sciences, and Lobachevsky State University of Nizhni Novgorod, Nizhny Novgorod, Russia
2. Department of Mathematics and Statistics, University of Nevada, Reno, Reno, Nevada
3. Geosciences Department, and Laboratoire de Météorologie Dynamique, CNRS and IPSL, École Normale Supérieure, Paris, France, and Department of Atmospheric and Oceanic Sciences, and Institute of Geophysics and Planetary Physics, University of California, Los Angeles, Los Angeles, California