1. Program in Atmospheric and Oceanic Sciences; Princeton University; Princeton New Jersey USA
2. Geophysical Fluid Dynamics Laboratory/National Oceanic and Atmospheric Administration; Princeton New Jersey USA
3. School of Engineering and Applied Sciences; Harvard University; Cambridge Massachusetts USA
4. Department of Chemistry and Department of Earth and Planetary Science; University of California; Berkeley California USA
5. Division of Engineering and Applied Science and Division of Geological and Planetary Sciences; California Institute of Technology; Pasadena California USA
6. Now at Environmental Protection Agency Region IX; San Francisco California USA
7. EOS Group; Department of Physics & Astronomy; University of Leicester; Leicester UK