Characterizing Wind-Generated Waves Using a Color Imaging Slope Gauge (CISG)

Wind-driven waves play a pivotal role in air-sea interactions, influencing processes such as energy dissipation and turbulent mixing. In this study, we employ a Color Imaging Slope Gauge (CISG) to measure surface wave slopes with high spatiotemporal resolution in the linear wind-wave tank at the University of Hamburg. Complementary techniques include a Laser Doppler Velocimetry (LDV) system for point-wise, two-dimensional velocity measurements; a wire gauge and a laser slope gauge for point measurements of wave height and slope, respectively; and an infrared radiometer capable of capturing surface temperature variations. These tools enable the investigation of thermal gradients and their correlation with wave dynamics. 

This research aims to examine the statistical properties of wind-generated waves and reconstruct their three-dimensional profiles to better understand their physical and kinematic behavior. A particular focus is placed on the mechanisms of microbreaking, which contribute to energy dissipation and capillary wave generation. To explore surface tension effects, surfactants are introduced to dampen gravity-capillary waves, allowing for detailed investigations of energy fluxes between wave regimes and the suppression of high-frequency wave components. 

The combined use of slope imaging, velocity measurements, and thermal detection enhances our ability to study the interplay of different physical processes at the air-sea interface. This work lays the groundwork for further investigations of wave behavior under varying environmental conditions. In particular, the findings of this study will provide critical insights into the small-scale processes driving wave dynamics and contribute to improved parameterizations for wave and climate models.