1. Department of Atmospheric and Oceanic Sciences; University of Colorado Boulder; Boulder CO USA
2. Cooperative Institute for Research in Environmental Sciences; University of Colorado Boulder; Boulder CO USA
3. Department of Atmospheric and Oceanic Sciences; University of Wisconsin-Madison; Madison WI USA
4. National Center for Atmospheric Research; Boulder Colorado USA
5. University Pierre et Marie Curie, Laboratoire de Météorologie Dynamique, Institut Pierre Simon Laplace Ecole Polytechnique; Palaiseau France