Simple tools for measuring wind fields above wind-generated water waves

Abstract

The vertical wind profiles above various parts of waves generated by a 9- to 10- meter/see wind in a short-fetch water-wind tunnel have been measured photographically using small, substantially neutrally buoyant soap bubbles. The turbulent boundary is thickest above the trough and thinnest above the erest. A maximum velocity ‘jet’ is measured just above the boundary layer at all points along the water waves. Lateral and reverse air flow is indicated near the waler surface just in front of the erest. Small floating beeswax disks have been used to measure the surface water velocity along the waves. Maximum water velocity occurs at the wave crest, with much slower moving water just in front of the erest. Under these conditions a rather sharp line of convergence must exist in front of the crest.