Johannes Karstensen is a research scientist at the Ocean Circulation and Climate Dynamics Division of the Leibniz-Institut für Meereswissenschaften in Kiel, Germany. He holds a diploma in physical oceanography and a PhD in natural sciences from the University of Hamburg. He worked as a visiting scientist at the Flinders University, Adelaide, Australia, and at the University of Copenhagen, Denmark; he did postdoctoral work at Lamont Doherty Earth Observatory, New York, USA, and at the Universidad de Concepción, Chile. His research interests cover the interaction of physical and biogeochemical processes in the ocean, large-scale ocean circulation, mixed layer dynamics, and ocean-observing technologies.