1. Institute of the Environment, 845 North Park Avenue, Suite 532, University of Arizona, Tucson, AZ 85721, USA.
2. National Center for Atmospheric Research, Boulder, CO, USA.
3. CNRS, Laboratoire de Météorologie Dynamique, Institut Pierre-Simon Laplace, Université Pierre et Marie Curie, Paris, France.
4. National Oceanic and Atmospheric Administration (NOAA)/National Climatic Data Center, Asheville, NC, USA.