Marc Buckley, Helmholtz-Zentrum Hereon, Geesthacht, Germany, Jeffrey Carpenter, Helmholtz-Zentrum hereon, Institute of Coastal Ocean Dynamics, Geesthacht, Germany, Jochen Horstmann, Helmholtz-Zentrum Hereon, Ocean Surface Dynamics, Geesthacht, Germany, Ivan Savelyev, US Naval Research Laboratory, Washington D.C., United States and Janina Tenhaus, Helmholtz-Zentrum Hereon, Institute of Coastal Ocean Dynamics, Geesthacht, Germany