1. Department of Meteorology and Geophysics, University of Vienna, Universitätsring 1, 1010 Vienna, Austria
2. Laboratory for Fluid Physics, Pattern Formation and Biocomplexity, Max Planck Institute for Dynamics and Self-Organisation, Am Faßberg 17, 37077 Göttingen, Germany
3. Institute for the Dynamics of Complex Systems, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany