1. GEOMAR Helmholtz Centre for Ocean Research Kiel; Germany
2. Faculty of Mathematics and Natural Sciences; University of Kiel; Germany
3. Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research; Bremerhaven Germany
4. Department of Physics and Electrical Engineering at the University of Bremen; Germany
5. Department of Physics, National Centre for Atmospheric Science (NCAS); University of Oxford; UK
6. European Centre for Medium-Range Weather Forecasts (ECMWF); Reading UK