1. Center of Computation and Visualization, Brown University, 180 George Street, Providence, Rhode Island 02906, USA
2. Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), Borgo Grotta Gigante 42c, 34010 Sgonico, Trieste, Italy
3. Computational Mathematics and Simulation Sciences (MCSS), École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
4. Complex Imaging Group, BP America, Houston, Texas 77079, USA