1. Department of Earth Science and Engineering, California Institute of Technology, Pasadena, CA 91125, USA
2. Jet Propulsion Laboratory (JPL), California Institute of Technology, Pasadena, CA 91109, USA
3. Institute of Environmental Physics, University of Bremen, 28334 Bremen, Germany
4. BC Consulting Limited, Alexandra 9320, New Zealand
5. School of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia
6. Department of Atmospheric Research, National Institute of Water and Atmospheric Research (NIWA) Ltd, Wellington 6021, New Zealand