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Christopher Zappa, who worked under the direction of APL-UW Principal Oceanographer Andy Jessup, will receive the Lorenz G. Straub Award for the most meritorious thesis in hydraulic engineering of 1999. The award was established by the Straub Memorial Fund at the University of Minnesota. (Read the announcement.) Chris earned a Ph.D. from the Department of Civil and Enviromental Engineering at the University of Washington in 1999. His dissertation, "Microscale Wave Breaking and its Effect on Air-Water Gas Transfer Using Infrared Imagery," is the result of laboratory and field experiments conducted in the Air-Sea Interaction and Remote Sensing Department at APL-UW. His thesis presents the first application of infrared imaging techniques to quantify the influence of microscale wave breaking on gas transfer across an air-water |
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interface. Microscale breaking waves are short wind-generated waves that become unstable and break without entraining air. For over two decades, the enhanced mixing caused by this elusive process had been suspected of playing a key role in regulating air-sea gas exchange. Until his use of infrared imaging techniques, an objective method to detect and characterize microscale wave breaking was unavailable. Thus, quantifying their effect on gas transfer had been impossible. But Zappa's compelling evidence proves that microscale wave breaking is indeed the mechanism that governs air-water gas transfer at low to moderate wind speeds. Zappa's original and creative research culminated in the development of powerful new remote sensing techniques for air-sea interaction studies. Identification of the physical process that regulates gas exchange will lead to significantly improved parameterizations for the gas transfer velocity. These parameterizations play a vital role in determining the accuracy of models for air-sea fluxes used to evaluate global climate change. Zappa is now a postdoctoral fellow at Woods Hole Oceanographic Institution. He and Jessup continue to collaborate on research, currently on an ONR-sponsored project, "Coupled Boundary Layer Air-Sea Transfer—Low Winds." For this multidisciplinary, multi-investigator project they are conducting airborne infrared imagery measurements to investigate horizontal temperature variability under low wind conditions. |
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