1. Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02540, USA
2. Université de Lorraine, CNRS, CRAN, F-54000 Nancy, France
3. Applied Physics Laboratory, University of Washington, Seattle, Washington 98105, USA
4. CNRS/GIPSA-Lab, 38402 Saint Martin d'Hères Cedex, France