1. Joint Program on the Science and Policy of Global Change Massachusetts Institute of Technology Cambridge MA USA
2. The Ecosystems Center Marine Biological Laboratory Woods Hole MA USA
3. Now at Atmospheric and Environmental Research Lexington MA USA
4. Department of Meteorology and Earth and Environmental Systems Institute Pennsylvania State University University Park PA USA
5. Laboratory for Aviation and the Environment, Department of Aeronautics and Astronautics Massachusetts Institute of Technology Cambridge MA USA