1. National Institute of Polar Research; Tokyo; Japan
2. Scripps Institution of Oceanography; University of California; San Diego, La Jolla; California; USA
3. Laboratoire de Glaciologie et Géophysique de l'Environnement; CNRS, Université Joseph Fourier Grenoble; Saint-Martin d'Héres; France
4. Meteorological Research Institute, Japan Meteorological Agency; Tsukuba; Japan
5. Centre for Ice and Climate; Niels Bohr Institute, University of Copenhagen; Copenhagen; Denmark
6. Byrd Polar Research Center; Ohio State University; Columbus; Ohio; USA