Abstract

In natural water bodies like oceans and lakes, biological organisms and other chemical species cover the water surface affecting the air-sea boundary conditions. At moderate wind speeds, short gravity wind waves occur on the water surface. It has been speculated that most of these short gravity waves are microscale breaking waves, which play a significant role in air-sea gas and heat transfer. This work reports on results from a series of laboratory experiments investigating the impact of surface contamination on the flow characteristics in the near surface region beneath short gravity waves at moderate wind speeds. In addition, the characteristics of parasitic capillary waves and their relation with microscale breaking waves are explored. In this study, the two-dimensional velocity fields were measured using digital particle image velocimetry (DPIV) and water surface temperature measurements were made simultaneously using infrared imagery. Results are reported for two wind speeds, 6.3 and 8.1 m s -1 . (Abstract shortened by UMI.)