CAREER: Parameterizations of Langmuir Turbulence in Shallow Water

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0846510 Tejada-MartinezThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Historically, Langmuir circulation (LC) is characterized by pairs of parallel counter-rotating vortices oriented approximately in the downwind direction driven by the wave- and wind-driven turbulence within the upper ocean mixed layer. The highly resolved field measurements of Gargett et al. (2004) first identified full-depth LC in shallow water with dominant effects on the mixing process and sediment re-suspension on the bottom boundary layer. These unique measurements have drastically changed perceptions of what turbulent processes are important on shallow shelves. The PI's large-eddy simulation (LES) of full-depth LC shows favorable agreement with the in-water observations of the turbulent structure. The PI will focus on LES computations of the interaction of LC with the bottom boundary layer and its impact on the gas transfer and temperature at the air-water interface. Studies will be guided and validated by comparisons with field measurements. Preliminary LES computations have revealed that the homogenizing action of LC introduces a deviation from the classical law-of-the-wall behavior often invoked for the bottom boundary layer. Furthermore, LES has shown that full-depth LC can increase the surface gas transfer efficiency by 30%. These studies will lead to new RANS (Reynolds-averaged Navier-Stokes) parameterizations accounting for its effects on bottom boundary layer turbulence in coastal regions. These studies will also lead to new bulk parameterizations of gas transfer at the air-water interface and temperature across the surface thermal boundary layer.An educational program is designed to introduce computational science and turbulence in the environment to high school and undergraduate students. Through the NSF-sponsored Research Experiences for Teachers program at USF, high school teachers will gain experience in scientific computations by participating in summer research projects. Simulations will also be incorporated into the PI's Basic Fluid Mechanics third-year undergraduate level course. A citizen science network will be established to record LC events in the Tampa Bay region and promote environmental awareness. This project is being co-funded by the Engineering, Geosciences, and Cyber Infrastructure Directorates.