In memoriam Prof. Will de Ruijter
Professor Will de Ruijter passed away on January 12, 2023. In the last ten years he increasingly suffered from the consequences of Parkinson’s disease. Over his long and eminent career, Will has made landmark contributions on a broad range of topics, including the dynamics of currents and fronts in the Dutch coastal zone and, in particular, the Agulhas Current system off South Africa.
Will graduated from Utrecht University in 1979 majoring in Applied Mathematics under guidance of Prof. W. Eckhaus, with a PhD thesis entitled: “On the asymptotic analysis of the large scale ocean circulation”. He then became project leader and later head of the Division of Coast and Sea, Delta Service and Tidal Waters at Rijkswaterstaat, the Netherlands. During this period, he spent two years at the University of Miami, USA, where he worked on the dynamics of the Agulhas Current. In 1986, he became full professor of Physical Oceanography at Utrecht University. This was his academic home for 30 years up to his retirement in 2016.
Throughout his career, and using theory, modeling and observations, Will has contributed significantly to the fundamental understanding of many topics, including the transport of suspended matter in the North Sea, the physics of Agulhas Leakage, and the importance of the Agulhas Current system in global climate. He predicted the existence of the Southern Hemisphere supergyre decades before it was observed with data from the ARGO float array. Much of this Agulhas research is summarized in the highly cited Nature paper “On the role of the Agulhas system in Ocean Circulation and Climate” (Beal et al., Nature, 472, 429-436, 2011), on which Will is a lead author.
Because of Will’s tireless efforts to conduct research in the Agulhas region, he and the associated Dutch oceanographic community are world renowned for their expertise on the circulation, variability and large-scale impacts of the Agulhas Current and Agulhas Leakage. Will foresaw the significance of this research and advocated for the work to be done, despite the high costs and difficult logistics. From 2000, Will coordinated the MARE (Mixing of Agulhas Rings Experiment) and ACSEX (Agulhas Current Sources Programme) programmes and co-coordinated the Long-term Oceanographic Observations (LOCO) programme of measurements in the Mozambique Channel. For his research accomplishments, Will was in 2000 elected as foreign fellow of the Royal Society of South Africa and in 2005 as member of the South African Academy of Science and Arts.
Through these programmes and also due to his membership of the CLIVAR Indian Ocean Panel, Will had a large international network of collaborators. One of these was his Agulhas “compadre” Johann Lutjeharms, who he visited frequently in Stellenbosch, South Africa, and who was a regular visitor in Utrecht. Another one was Co van de Kreeke, who Will often visited in Miami. In each of these collaborations and forums, Will participated with a source of clear vision and great ideas, and with a magnanimous leadership style that encouraged collaboration and allowed younger colleagues to grow and take the spotlight. Many of Will’s PhD students have gone on to pursue highly successful and productive careers in science, both within the Netherlands and abroad.
His great leadership talents, excellent communication skills, strong vision and good sense of humor also enabled Will to put the broader climate community in the Netherlands on the world map. In 1989, Will was one of the co-founders of Netherlands Centre for Coastal Research. He was founding Director of the Institute for Marine & Atmospheric Research (IMAU) in 1992, as well as founding Director of the Dutch Graduate School for Atmospheric and Marine Science (presently the Buys-Ballot Research School). Owing to his continuous drive, the IMAU strongly expanded over the years and it became a world-renowned institute for climate physics. Will also did not shy away to take on large administrational tasks, as he was Dean of the Faculty of Physics and Astronomy from 2003 to 2006 and, from 2006 until his retirement in 2016, he was Scientific Director of the IMAU. In addition, he participated in many governing and advisory boards in the Netherlands (e.g., Dutch Science Foundation, Royal Netherlands Institute for Sea Research, Royal Dutch Meteorological Institute) and abroad (e.g., Institut fur Meereskunde, Kiel). Will was an excellent and motivating teacher, giving courses on physical and dynamical oceanography, and directed the masterprogramme Meteorology, Physical Oceanography and Climate (now Climate Physics) from 2003 to 2014. For his extraordinary contributions to science and society, Will was knighted in the Order of the Dutch Lion on June 20, 2011.
Will leaves a large legacy in the Physical Oceanography, Coastal Oceanography and Climate Physics research fields through his scientific papers, through his students, and through his national and international leadership. We both, and many others, were strongly influenced by his extraordinary physical intuition, broad vision and kind personality. He will be sorely missed.
Huib de Swart and Henk Dijkstra
January 17, 2023