JOOST A. BUSINGER (1924-2023)

BY STEVEN BUSINGER¹
SUBMITTED BY THE NAE HOME SECRETARY

JOOST ALOIS BUSINGER, a pioneer of modern boundary layer meteorology, passed away in December 2023, just shy of his 100th birthday. Joost was born in Haarlem, The Netherlands. At a young age, a warm day in March sparked what would become a lifelong passion for weather. His grandfather, a Swiss immigrant to Amsterdam, passed Swiss citizenship to Joost through his father, Leopold Alois Businger. A Swiss passport later allowed him to pursue studies in physics at Utrecht University in 1942, unhindered by the German occupation.

Meteorology was not available as a specialization within the physics department at the time, so he pursued heat transfer research under Professor Erwin van der Held, where he discovered that turbulent exchange could be approached using dimensional analysis. He graduated in 1947 and began working at the Institute for Horticultural Engineering in Wageningen four days a week, leaving time to continue his dissertation research at Utrecht. He married in 1949. In Wageningen, he worked on greenhouse climate control and developed a method for frost protection that remains in use today.

Joost completed his dissertation in 1954, focusing on turbulent exchange processes in the atmospheric surface layer (ASL), the first approximately 100 meters of the atmospheric boundary layer (ABL). He introduced the concept of “roughness length” as a relevant scaling parameter, independently of Russian researchers Andrei Monin and Alexander Obukhov,² whose 1954 paper laid the foundation for the now widely used Obukhov length. Joost later accepted that the Monin-Obukhov (MO) theory was more adequate than his own, though subsequent research confirmed that roughness length remains an important scale in boundary layer theory.

Joost was one of the first to recognize the importance of the ABL in weather and climate models, as it forms the critical interface between the free atmosphere and the Earth’s surface. He understood how much research was needed to bridge the gap between synoptic meteorology and boundary layer meteorology, and he became a pioneer in doing so. In 1956, with limited support for young scientists in the Netherlands, he accepted a research associate position at the University of Wisconsin. One of his first assignments was to analyze raw data collected with a sonic anemometer developed by Verner Suomi (NAE 1966).

In 1957, Joost became an assistant professor at the University of Washington (UW). There, with his first graduate student, Jagadish Chandran Kaimal, he advanced the sonic anemometer and adapted it to measure turbulent fluxes using the eddy correlation method. During a sabbatical in Australia in 1965-66, he collaborated with A.J. Dyer and William Christopher Swinbank to lay the theoretical foundation for what became the Dyer-Businger MO relationships. These profile descriptions were finalized during the Kansas field experiment of 1967-68, organized by the Air Force Cambridge Research Laboratories, where Kaimal had begun working. The fieldwork culminated in the milestone publication on MO flux-profile relationships,³ an article that has since been cited nearly 5,000 times. It was a natural evolution of the ideas he began developing as a student in Utrecht during World War II.

Today, sonic anemometers are used globally with digital data loggers, but at that time, Joost’s work required manually processing strips of x-y writer recordings – an exceptionally painstaking effort, which makes the 1971 paper all the more impressive. He considered many of his other contributions equally important. For more on his career and legacy, see De Bruin & Nieuwstadt⁴ and Steven Businger.⁵

While on sabbatical at the Royal Netherlands Meteorological Institute in 1975, Joost wrote his first article on atmosphere-ocean interactions and helped foster new collaborations, contributing to the Netherlands’ rich tradition of boundary layer research.

As a textbook author, Joost’s knowledge remains highly influential. Key publications include An Introduction to Atmospheric Physics (with Robert G. Fleagle; Academic Press, 1980); Workshop on Micrometeorology (American Meteorological Society, 1973); A Short Course on Atmospheric Turbulence and Air Pollution Modeling (Springer Netherlands, 1982) and Atmosphere–Ocean Interaction (with Eric B. Kraus; Oxford University Press, 1994).

After taking early retirement from UW in 1982, Joost moved to the National Center for Atmospheric Research in Boulder, where he developed the Atmosphere/Surface Turbulent Exchange Research Facility to promote ABL research. He also collaborated with Steven Oncley on the conditional sampling method – also known as the relaxed eddy accumulation approach – which was patented. In 1989, he retired fully and helped design and build a sustainable home in the San Juan Islands of Washington State. Nature conservation and the judicious use of energy and water were central values in his life.

Joost will be remembered as a kind and modest man who, despite his international reputation, remained approachable and generous to young researchers. He is survived by his wife, Marianne; three children, Ferdi, Steven, and Margi; and two stepchildren, Bret and Erica.

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¹Reprinted with permission of Department of Atmospheric Sciences and Climate, University of Washington.
²Monin AS, Obukhov AM. 1954. Basic laws of turbulent mixing in the surface layer of the atmosphere. Transactions of the Geophysical Institute, Academy of Sciences of the USSR 24(151):163-87. (Roughly translated; Originally published in Russian.)
³Businger JA, Wyngaard JC, Isumi Y, Bradley EF. 1971. Flux-profile relationships in the atmospheric surface layer. Journal of the Atmospheric Sciences 28(2):181-89.
⁴De Bruin H, Nieuwstadt F. 2005. Joost Businger–His career in boundary-layer meteorology in a nutshell. Boundary-Layer Meteorology 116:149-59.
⁵Businger S. 2025. Joost Businger—A pioneer in atmospheric boundary layer research. Bulletin of the American Meteorological Society 106(1):E204-16.