1. Department of Ocean Sciences, University of California Santa Cruz 1 , 1156 High St., Santa Cruz, California 95064, USA
2. Department of Oceanography, Naval Postgraduate School 2 , 1 University Circle, Monterey, California 93943, USA
3. Scripps Institution of Oceanography, University of California San Diego 3 , La Jolla, California 92093, USA
4. Nansen Environmental and Remote Sensing Center 4 , Bergen, Norway
5. Woods Hole Oceanographic Institution 5 , Woods Hole, Massachusetts 02543, USA