37th International Liège Colloquium on Ocean Dynamics, GAS TRANSFER AT WATER SURFACES, May 2- 6 2005 Modeling the turbulence generated by microscale breaking waves

The turbulence generated by microscale breaking waves beneath the air-water interface is simulated numerically. The goal of this study is to improve our understanding of the physical processes governing the transfer of gases across the ocean surface. The model predictions will ultimately be used to aid the development of a new parameterization of air-sea gas transfer that accounts for microscale wave breaking. Our specific objective is to quantitatively assess the hypothesis that microscale wave breaking is an important factor in the global air-sea flux of carbon dioxide. Microscale breaking waves are small scale breaking waves for which surface tension is sufficiently strong to prevent air entrainment. They are about 10 to 50 cm in length and a few centimeters in height. In the ocean microscale breaking waves occur much more frequently than white caps. Laboratory investigations have shown that at wind speeds from 4 to 10 m·s-1 microscale wave breaking is the dominant physical mechanism that controls the rate of heat, momentum and gas transfer across the air-water interface [Zappa et al. 2001, Siddiqui et al. 2004]. Wave breaking provides a mechanism for the injection of both kinetic energy and momentum from air to water. A one dimensional 2.5 level turbulence closure scheme is used to model the enhanced near surface turbulence produced by microscale breaking waves. The mode