Measurement of surface velocities and shears at a wavy air–water interface using particle image velocimetry

 Measurements have been accomplished within the aqueous surface viscous sublayer of wind-forced microscale breaking waves using particle image velocimetry. These measurements have been used to derive surface velocities and tangential stresses. Assessment is made of the performance of the experimental equipment and techniques developed to accomplish these measurements. Comparison is made with previous studies of viscous sublayer behaviour at the air–water interface and at smooth solid surfaces. Received: 7 June 1996/Accepted: 30 April 1997