Spatio-temporal slope measurement of short wind waves under the influence of surface films at the Heidelberg Aeolotron

A novel, high resolution Imaging Slope Gauge (ISG) at the Heidelberg Aeolotron is presented. The instrument allows measurements of the two-dimensional slope of short wind-driven water waves at unprecedented temporal and spatial resolution. Wave number spectra are measured up to k = 13000 rad/m with a temporal resolution of more than 1500 Hz. The high sampling frequency eliminates aliasing up to wave numbers of about k = 2660 rad/m. A new non-linear calibration and data processing work flow has been implemented to convert raw camera images into wave slope in the range of \pm 0.96. The average statistical measurement error is estimated to be \Delta s_rms = 0.018, a significant improvement compared to previous Color Imaging Slope Gauge setups. Spectrally resolved measurements of the influence of various surface-active materials (surfactants) on small-scale waves are reported. The wave damping effects of different substances are analyzed. It is shown that, except for low wind speeds, gas transfer velocities across the air-sea boundary layer can be parametrized with the mean square slope of the waves, independent of the specific type of surfactant that is used.

Level thesis:degree_level

master

Grantor dc:publisher

Universität Heidelberg

Year

2014

Author dc:creator

• Reith, Svenja

Contributors dc:contributor

• Jähne, Bernd

Repository record source_url

http://www.ub.uni-heidelberg.de/archiv/17697

OAI identifier oai:identifier

oai:archiv.ub.uni-heidelberg.de:17697