SO2 Transfer across the Air-Water Interface

A newly developed laser-induced fluorescence technique to measure high-resolution vertical concentration profiles of the tracer sulfur dioxide above the air-water interface is presented. The concentration profiles can be used to study the transport mechanisms in the air-sided boundary layer at a wavy interface including the gas transfer velocity, turbulent concentration fluctuations, and the partitioning of gas transfer between air and water. The imaging technique was tested in a wind-wave facility under invasion conditions. A proof of principle is presented as well as a first evaluation of the capabilities and uncertainties of the method. In combination with particle imaging velocimetry, this measurement technique will allow for a detailed study of the transport processes across the mass boundary layer.