1. School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK.
2. Kennedy School of Government, Harvard University, Cambridge, Massachusetts, USA.
3. BAER Institute, Moffett Field, California, USA.
4. Department of Geosciences, Idaho State University, Pocatello, Idaho, USA.
5. School of Geography and Earth Sciences, McMaster University, Hamilton, Canada.
6. NASA Ames Research Center, Moffett Field, California, USA.