Gabriel George Katul was awarded the James B. Macelwane Medal at the AGU Spring Meeting Honors Ceremony, which was held on 29 May 2002, in Washington, D.C. The medal recognizes significant contributions to the sciences by a young scientist of outstanding ability.
“Gabriel Katul grew up in Beirut, Lebanon, where he completed his bachelor’s degree at the American University of Beirut. He then came to the United States for graduate school. He obtained his master’s degree at Oregon State University, where he worked with Professor Richard Cuenca on evaporation modeling and measurement. I was then most fortunate to have Gabriel join me at U.C. Davis for his Ph.D. (thanks to recommendations from Richard), where I had just started as assistant professor. Upon his arrival, it was immediately clear that Gabriel was someone extremely special. He had the remarkable ability to quickly define the most critical aspects of a problem and then without hesitation or fear bring the best experimental, theoretical, and modeling approaches to bear. After earning his Ph.D. in 1993, he started as assistant professor at Duke University, where today he is professor in the School of the Environment and the Department of Civil and Environmental Engineering.
“His discoveries on the interactions between the land and the atmosphere with his students and colleagues at Duke rank as some of the most profound and important in the field over the past ten years. His work cuts across both hydrology and meteorology, and he has published extensively in both communities. It is not possible to cover all the important research he has accomplished in such a short period of time, but I will attempt to highlight some critical findings.
“The fundamental issue he has addressed is, How do the coupled physical and evolving biological systems within the land-atmosphere continuum express themselves in biogeochemical fluxes when variations in forcing (e.g., variable precipitation, increased atmospheric CO2, or nitrogen deposition) are active over a broad spectrum of time scales (fractions of seconds to decades)?
“Gabriel has pioneered our understanding of the role of organized multi-scale eddy motion in the transport of heat and water vapor from forested systems. Localized and energy-containing eddy motion were identified from newly-derived Lorentz wavelet thresholding approaches and applied to field measurements his group collected over many forest types. On the basis of his findings, cumulant discard approximations are now used by the micro-meteorological community to construct new closure models for the momentum and scalar flux divergences that explicitly account for the ejection-sweep cycle so crucial in land-atmosphere exchange.
“Gabriel has developed the theory on the role of so-called inactive eddy motion on atmospheric surface-layer turbulence. This theory is the first to explain why surface-layer vertical velocity variances follow the classical Monin-Obukhov similarity theory, but the horizontal velocity and static pressure do not.
“Gabriel and his students have developed, and tested with experiment, forward and inverse models to infer space-time evolution of CO2 sources, sinks, and fluxes within forested canopies. This work is now the basis for CO2 source/sink identification. These models are the first to include ecophysiological theories and enzyme kinetics, radiative transfer schemes, hydraulic theory of plants, novel approaches to modeling canopy turbulence, and water-carbon optimization theories to model stomatal function.
“On a personal note, Gabriel is a wonderful human being and a genuine friend to all his colleagues and students. I am delighted to present Professor Gabriel G. Katul of Duke University, 2002 Macelwane Medalist.”
—MARC PARLANGE, Johns Hopkins University, Baltimore, Md.
“Thank you Marc for your kind citation. I am honored by this award, which I share with many people.
“I was fortunate to start my career with Richard Cuenca at Oregon State University and Marc Parlange at the University of California at Davis as mentors, inspirational colleagues, and friends. With Marc Parlange, much of our effort was dedicated to injecting fluid mechanics into studies of land-atmosphere exchange.
Upon leaving graduate school, I was lucky to join the Nicholas School of the Environment and Earth Sciences at Duke University, where I formed partnerships with many ecophysiologists and ecologists. In particular, I had the pleasure of working with exceptional colleagues like Ram Oren and David Ellsworth whose insights about ecosystem science led us to discover numerous intersections between ecology and fluid mechanics, and which further led to exciting manuscripts on coupled water vapor and carbon dioxide exchange between forests and the atmosphere. Early on, we realized that the combination of fluid mechanics, ecology, and hydrology needed new statistical tools to unfold the multi-scale biological and physical system. While I wish to claim credit for a higher order design at this junction, the facts remain that luck brought me in contact with Brani Vidakovic at Duke University. His expertise and enthusiasm on multi-scale analysis was crucial to numerous papers utilizing wavelet transformations and information theory.
I was also fortunate to end my graduate work at U.C. Davis and start my professional career with John Albertson, a colleague and friend whose insights and guidance on almost all aspects of fluid dynamics and statistical mechanics I had to consult before any real progress was made on more than 30 manuscripts. Most importantly, I wish to acknowledge the contribution of my graduate students Cheng-I Hsieh, Chun-Ta Lai, Mario Siqueira, and Karen Wesson whose team spirit, enthusiasm, and optimism to tackle almost any research problem created a unique spark in our research.
“Thanks again to the Macelwane Medal committee for their confidence and to the American Geophysical Union.”
—GABRIEL GEORGE KATUL, Duke University, Durham, N.C.