1. Laboratoire des Ecoulements Géophysiques et Industriels, Institut de Mécanique de Grenoble, 38041 Grenoble Cedex, France
2. Department of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, USA.
3. Senior Research Fellow with the Institute of Oceanographic Sciences, Deacon Laboratory, Wormley, GU8 5UB, UK.