1. Potsdam Institute for Climate Impact Research, 14482 Potsdam, Germany.
2. Laboratoire d'Etudes en Géophysique et Océanographie Spatiales, 31400 Toulouse, France.
3. Marine and Atmospheric Research and Antarctic Climate and Ecosystems Cooperative Research Centre, Commonwealth Scientific and Industrial Research Organisation, Hobart Tasmania, 7001, Australia.
4. NASA Goddard Institute for Space Studies (GISS), New York, NY 10025, USA.
5. Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA.