1. Department of Atmospheric and Oceanic Sciences, McGill University, 805 Sherbrooke Street West, Montreal, Quebec, Canada H3A OB9
2. Lamont-Doherty Earth Observatory of Columbia University, 61 route 9W, Palisades, NY 10964, USA
3. NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025, USA
4. Barnard College, 3009 Broadway, New York, NY 10027, USA