Wilken-Jon von Appen, Alfred Wegener Institute, Helmholtz-Centre for Polar and Marine Research, Bremerhaven, Germany, Rebecca McPherson, Alfred Wegener Institute Helmholtz-Center for Polar and Marine Research Bremerhaven, Bremerhaven, Germany, Laura de Steur, Royal Netherlands Institute for Sea Research, Physical Oceanography, Den Burg, Netherlands, Torsten Kanzow, Alfred-Wegener-Institute, Bremerhaven, Germany, Agnieszka Beszczynska-Möller, Institute of Oceanology Polish Academy of Sciences, Department of Physical Oceanography, Sopot, Poland and Angelika Renner, Institute of Marine Research, Tromsø, Norway