%0 Generic
%A Friman, Sonja Isabella
%C Heidelberg
%D 2020
%F heidok:28310
%K gas transfer, momentum transfer, mass boundary layer, wind-wave tank, laser-induced fluorescence, particle streak velocimetry, UV spectroscopy, gas transfer velocity, friction velocity
%R 10.11588/heidok.00028310
%T Laboratory investigations of concentration and wind profiles close to the wind-driven wavy water surface
%U https://archiv.ub.uni-heidelberg.de/volltextserver/28310/
%X Studying the air- and water-sided boundary layers is vital to understand the exchange of momentum and gases between ocean and atmosphere. While the water-sided mass boundary layer can be studied with several imaging techniques, no such technique was available for the air side. In the scope of this thesis, a laser-induced fluorescence (LIF) technique was developed, where the tracer sulfur dioxide (SO2) is illuminated with a UV laser and its fluorescence is imaged, yielding near-surface concentration profiles of SO2 with a resolution of up to 20 μm. The profiles can be used to quantify reliable boundary layer thicknesses and gas transfer velocities, which was shown in a proof-of-principle experiment in a wind-wave tank.    In a second experiment at two fetches of a larger wind-wave tank, the SO2 LIF technique was employed together with particle streak velocimetry, measuring local wind speeds, and surface elevation measurements. This experiment is the first simultaneous and collocated measurement of mass and momentum transfer in the air-sided mass boundary layer. The mean concentration and wind speed profiles as well as their fluctuations were analyzed and compared. Including the surface elevations, the modulation of the transport processes by waves was analyzed, resulting in wave-phase averaged transfer velocities.