The impact of small-scale Langmuir circulations on air-water interface and surface cool skin
Date
2016
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Publisher
University of Delaware
Abstract
Mixing and turbulence take a great role in air-sea interactions nowadays. When wind starts to blow over a quiescent air-sea interface, both currents and surface waves are initially generated. The interaction between the wind-driven waves and currents leads to the generation of Langmuir circulation (LC) consisting of counter rotating vortices aligned with the wind. Shortly thereafter, Langmuir turbulence (LT), that is multiple scales of LC, appear. In LT, length scales range from several centimeters when short capillary waves first appear up to tens of meters when the spectrum of waves broadens. The main purpose of this thesis is to research how small-scale LC develops and evolves and its impact to mixing and turbulence, especially on the disruption of the near surface molecular layers of heat and momentum. The results are from laboratory experiments performed at the air-sea interaction lab at University of Delaware in Lewes DE. In this experiment, we used surface infrared imagery and subsurface Particle Image Velocitmetry techniques. We saw that the evolution of from organized small scale LC to LT is very rapid leading to intense surface mixing whereby momentum initially transferred to the surface through viscosity efficiently mixes the near surface layers. Subsurface turbulence measurements are presented in the context of scalar (gas) flux through the air-water interface.